Introduction

Subplot is software to help capture and communicate acceptance criteria for software and systems, and how they are verified, in a way that's understood by all project stakeholders. The current document contains the acceptance criteria for Subplot itself, and its architecture.

The acceptance criteria are expressed as scenarios, which roughly correspond to use cases. The scenario as accompanied by explanatory text to explain things to the reader. Scenarios use a given/when/then sequence of steps, where each step is implemented by code provided by the developers of the system under test. This is very similar to the Cucumber tool, but with more emphasis on producing a standalone document.

Acceptance criteria and acceptance tests

We define the various concepts relevant to Subplot as follows:

• Acceptance criteria: What the stakeholders require of the system for them to be happy with it and use it.

• Stakeholder: Someone with a keen interest in the success of a system. They might be a paying client, someone who uses the system, or someone involved in developing the system. Depending on the system and project, some stakeholders may have a bigger say than others.

• Acceptance test: How stakeholders verify that the system fulfills the acceptance criteria, in an automated way. Some criteria may not be possible to verify automatically.

• Scenario: In Subplot, the acceptance criteria are written as freeform prose, with diagrams, etc. The scenarios, which are embedded blocks of Subplot scenario language, capture the mechanisms of verifying that criteria are met - the acceptance tests - showing step by step how to determine that the software system is acceptable to the stakeholders.

A basic workflow for using Subplot

We recommend the following initial approach to using Subplot, which you can vary based on your particular needs and circumstances.

1. Start with a small acceptance document that you think expresses some useful requirements.
2. Write some acceptance criteria and have them agreed among the stakeholders.
3. Write scenarios to verify that the criteria are met, and have those scenarios agreed by the stakeholders.
4. Write bindings and test functions, so that as the code is written it can be tested against the acceptance criteria.
5. Iterate on this in short cycles to maximise discussion and stakeholder buy-in.

You definitely want to keep the subplot document source code in version control. You certainly need to have people who can write technical text that's aimed at all your stakeholders.

Subplot architecture

Subplot reads an input document, in Markdown, and generates a typeset output document, as HTML, for all stakeholders to understand. Subplot also generates a test program, in Python, that verifies the acceptance criteria are met, for developers and testers and auditors to verify the system under test meets its acceptance criteria. The generated program uses code written by the Subplot user to implement the verification steps. The diagram below illustrates this and shows how data flows through the system.

Subplot generated HTML itself.

Subplot actually consists mainly of two separate programs: subplot docgen for generating output documents, and subplot codegen for generating the test program. There are a couple of additional tools (subplot metadata for reporting meta data about a Subplot document, and subplot extract for extracting embedded files from a subplot document.

Thus a more detailed architecture view is shown below.

A fairy tale of acceptance testing

The king was upset. This naturally meant the whole court was in a tizzy and chattering excitedly at each other, while trying to avoid the royal wrath.

"Who will rid me of this troublesome chore?" shouted the king, and quaffed a flagon of wine. "And no killing of priests, this time!"

The grand hall's doors were thrown open. The grand wizard stood in the doorway, robe, hat, and staff everything, but quite still. After the court became silent, the wizard strode confidently to stand before the king.

"What ails you, my lord?"

The king looked upon the wizard, and took a deep breath. It does not do to shout at wizards, for they control dragons, and even kings are tasty morsels to the great beasts.

"I am tired of choosing what to wear every day. Can't you do something?"

The wizard stoked his long, grey beard. He turned around, looked at the magnificent outfits worn by members of the court. He turned back, and looked at the king.

"I believe I can fix this. Just to be clear, your beef is with having to choose clothing, yes?"

"Yes", said the king, "that's what I said. When will you be done?"

The wizard raised his staff and brought it back down again, with a loud bang.

"Done" said the wizard, smugly.

The king was amazed and started smiling, until he noticed that everyone, including himself, was wearing identical burlap sacks and nothing on their feet. His voice was high, whiny, like that of a little child.

"Oh no, that's not at all what I wanted! Change it back! Change it back now!"

The morale of this story is to be clear and precise in your acceptance criteria, or you might get something other than what you really, really wanted.

Motivation for Subplot

Keeping track of requirements and acceptance criteria is necessary for all but the simplest of software projects. Having all stakeholders in a project agree to them is crucial, as is that all agree how it is verified that the software meets the acceptance criteria. Subplot provides a way for documenting the shared understanding of what the acceptance criteria are and how they can be checked automatically.

Stakeholders in a project may include:

• those who pay for the work to be done; this may be the employer of the developers for in-house projects ("customer")
• those who use the resulting systems, whether they pay for it or not ("user")
• those who install and configure the systems and keep them functional ("sysadmin")
• those who support the users ("support")
• those who test the project for acceptability ("tester")
• those who develop the system in the first place ("developer")

The above list is incomplete and simplistic, but suffices as an example.

All stakeholders need to understand the acceptance criteria, and how the system is evaluated against the criteria. In the simplest case, the customer and the developer need to both understand and agree so that the developer knows when the job is done, and the customer knows when they need to pay their bill.

However, even when the various stakeholder roles all fall upon the same person, or only on people who act as developers, the Subplot tooling can be useful. A developer would understand acceptance criteria expressed only in code, but doing so may take time and energy that are not always available. The Subplot approach aims to encourage hiding unnecessary detail and documenting things in a way that is easy to understand with little effort.

Unfortunately, this does mean that for a Subplot output document to be good and helpful, writing it will require effort and skill. No tool can replace that.

Using this document to verify Subplot works

This document ("subplot") can be used to verify Subplot itself from its source tree or an installed Subplot. The default is to test Subplot from the source tree, and the ./check script does that. You can run this in the source tree to build Subplot and then verify it using itself:

$ cargo build -q
$ cargo run --bin subplot codegen -- subplot.md -o test.py
$ python3 test.py
... much output
OK, all scenarios finished successfully
$

To test an installed Subplot, generate the test program, and tell the test program where Subplot is installed. Again, in the Subplot source tree:

$ cargo build -q
$ cargo run --bin subplot codegen -- subplot.md -o test.py
$ python3 test.py  --env SUBPLOT_DIR=/usr/local/bin
... much output
OK, all scenarios finished successfully
$

You can do this with an installed Subplot as well:

$ cargo clean
$ /usr/local/bin/subplot codegen subplot.md -o test.py
$ python3 test.py --env SUBPLOT_DIR=/usr/local/bin
... much output
OK, all scenarios finished successfully
$

The generated test program is self-standing, and can be run from anywhere. However, to generate it you need to be in the Subplot source tree. You can move it elsewhere after generating it, you if you prefer.

Requirements

This chapter lists requirements for Subplot. These requirements are not meant to be automatically verifiable. For specific, automatically testable acceptance criteria, see the later chapter with acceptance tests for Subplot.

Each requirement here is given a unique mnemonic id for easier reference in discussions.

• UnderstandableTests

  Acceptance tests should be possible to express in a way that's easily understood by all stakeholders, including those who are not software developers.

  Done but requires the Subplot document to be written with care.

• EasyToWriteDocs

  The markup language for writing documentation should be easy to write.

  Done by using Markdown.

• AidsComprehension

  The formatted human-readable documentation should use good layout and typography to enhance comprehension.

  In progress — we currently only output HTML, but may add PDF output back later.

• CodeSeparately

  The code to implement the acceptance criteria should not be embedded in the documentation source, but be in separate files. This makes it easier to edit without specialised tooling.

  Done by keeping scenario step implementations in a separate file.

• AnyProgammingLanguage

  The developers implementing the acceptance tests should be free to use a language they're familiar and comfortable with. Subplot should not require them to use a specific language.

  Not done — only Python supported at the moment.

• FastTestExecution

  Executing the acceptance tests should be fast.

  Not done — the generated Python test program is simplistic and linear.

• NoDeployment

  The acceptance test tooling should assume the system under test is already deployed and available. Deploying is too big of a problem space to bring into the scope of acceptance testing, and there are already good tools for deployment.

  Done by virtue of letting those who implement the scenario steps worry about it.

• MachineParseableResults

  The tests should produce a machine parseable result that can be archived, post-processed, and analyzed in ways that are of interest to the project using Subplot. For example, to see trends in how long tests take, how often tests fail, to find regressions, and to find tests that don't provide value.

  Not done — the generated test program is simplistic.

Subplot input language

Subplot reads three input files, each in a different format:

• The document file in GitHub Flavored Markdown.
• The bindings file, in YAML.
• The functions file, in Bash or Python.

Subplot interprets marked parts of the input document specially. These are fenced code blocks tagged with the sceanrio, file, or example classes.

Scenario language

The scenarios are core to Subplot. They express what the detailed acceptance criteria are and how they're verified. The scenarios are meant to be understood by both all human stakeholders and the Subplot software. As such, they are expressed in a somewhat stilted language that resembles English, but is just formal enough that it can also be understood by a computer.

A scenario is a sequence of steps. A step can be setup to prepare for an action, an action, or an examination of the effect an action had. For example, a scenario to verify that a backup system works might look like the following:

~~~scenario
given a backup server
when I make a backup
and I restore the backup
then the restored data is identical to the original data
~~~

This is not magic. The three kinds of steps are each identified by the first word in the step.

• given means it's a step to set up the environment for the scenario
• when means it's a step with the action that the scenario verifies
• then means it's a step to examine the results of the action

The and keyword is special in that it means the step is the same kind as the previous step. In the example, on line 4, it means the step is a when step.

Each step is implemented by a bit of code, provided by the author of the subplot document. The step is bound to the code via a binding file, via the text of the step: if the text is like this, then call that function. Bindings files are described in detail shortly below.

The three kinds of steps exist to make scenarios easier to understand by humans. Subplot itself does not actually care if a step is setup, action, or examination, but it's easier for humans reading the scenario, or writing the corresponding code, if each step only does the kind of work that is implied by the kind of step it's bound to.

Using Subplot's language effectively

Your subplot scenarios will be best understood when they use the subplot language in a consistent fashion, within and even across different projects. As with programming languages, it's possible to place your own style on your subplots. Indeed, there is no inherent internal implementation difference between how given, when and then steps are processed (other than that given steps often also have cleanup functions associated with them).

Nonetheless we have some recommendations about using the Subplot language, which reflect how we use it in Subplot and related projects.

When you are formulating your scenarios, it is common to try and use phraseology along the lines of if this happens then that is the case but this is not language which works well with subplot. Scenarios describe what will happen in the success case. As such we don't construct scenarios which say if foo happens then the case fails, instead we say when I do the thing then foo does not happen. This is a subtle but critical shift in the construction of your test cases which will mean that they map more effectively to scenarios.

Scenarios work best when they describe how some entity (human or otherwise) actually goes about successfully achieving their goal. They start out by setting the scene for the goal (given) they go on to describe the actions/activity undertaken in order for the goal to be achieved (when) and they describe how the entity knows that the goal has been achieved (then). By writing in this active goal-oriented fashion, your scenarios will flow better and be easier for all stakeholders to understand.

In general you should use given statements where you do not wish to go into the detail of what it means for the statement to have been run, you simply wish to inform the reader that some precondition is met. These statements are often best along the lines of given a setup which works or given a development enviroment or somesuch.

The when statements are best used to denote active steps. These are the steps which your putative actors or personae use to achieve their goals. These often work best in the form when I do the thing or when the user does the thing.

The then statements are the crux of the scenario, they are the validation steps. These are the steps which tell the reader of the scenario how the actor knows that their action (the when steps) has had the desired outcome. This could be of the form then some output is present or then it exits successfully.

With all that in mind, a good scenario looks like

given the necessary starting conditions
when I do the required actions
then the desired outcome is achieved

Given all that, however, it's worth considering some pitfalls to avoid when writing your scenarios.

It's best to avoid overly precise or overly technical details in your scenario language (unless that's necessary to properly describe your goal etc.) So it's best to say things like then the output file is valid JSON rather than then the output file contains {"foo": "bar", "baz": 7}. Obviously if the actual values are important then again, statements such as then the output file has a key "foo" which contains the value "bar" or similar.

Try not to change "person" or voice in your scenarios unless there are multiple entities involved in telling your stories. For example, if you have a scenario statement of when I run fooprogram do not also have statements in the passive such as when fooprogram is run. It's reasonable to switch between when and then statements (then the output is good) but try not to have multiple then statements which switch it up, such as then I have an output file, and the output file is ok.

If you're likely to copy-paste your scenario statements around, do not use and as a scenario keyword, even though it's valid to do so. Instead start all your scenario statements with the correct given, when, or then. The typesetter will deal with formatting that nicely for you.

Document markup

Subplot parses Markdown input files using GitHub-flavored Markdown.

Subplot extends Markdown by treating certain certain tags for fenced code blocks specially. A scenario, for example, would look like this:

```scenario
given a standard setup
when peace happens
then everything is OK
```

The scenario tag on the code block is recognized by Subplot, which will typeset the scenario (in output documents) or generate code (for the test program) accordingly. Scenario blocks do not need to be complete scenario. Subplot will collect all the snippets into one block for the test program. Snippets under the same heading belong together; the next heading of the same or a higher level ends the scenario.

For scenario blocks you may not use any attributes. All attributes are reserved for Subplot. Subplot doesn't define any attributes yet, but by reserving all of them, it can add them later without it being a breaking change.

For embedding test data files in the Markdown document, Subplot understands the file tag:

~~~{#filename .file}
This data is accessible to the test program as 'filename'.
~~~

The .file attribute is necessary, as is the identifier, here #filename. The generated test program can access the data using the identifier (without the #).

Subplot also understands the dot and roadmap tags, and can use the Graphviz dot program, or the roadmap Rust crate, to produce diagrams. These can useful for describing things visually.

When typesetting files, Subplot will automatically number the lines in the file so that documentation prose can refer to sections of embedded files without needing convoluted expressions of positions. However if you do not want that, you can annotate the file with .noNumberLines.

For example…

~~~{#numbered-lines.txt .file}
This file has numbered lines.

This is line number three.
~~~

~~~{#not-numbered-lines.txt .file .noNumberLines}
This file does not have numbered lines.

This is still line number three, but would it be obvious?
~~~

…renders as:

This file has numbered lines.

This is line number three.

This file does not have numbered lines.

This is still line number three, but would it be obvious?

Use embedded file

This scenario makes sure the sample files are used in a scenario so that they don't cause warnings.

Document metadata

Document metadata is read from a YAML file. This can used to set the document title, authors, date (version), and more. Crucially for Subplot, the bindings and functions files are named in the metadata block, rather than Subplot deriving them from the input file name.

title: "Subplot"
authors:
- The Subplot project
date: work in progress
markdowns:
- subplot.md
bindings:
- subplot.yaml
impls:
  python:
    - subplot.py

There can be more than one bindings or functions file: use a YAML list.

Bindings file

The bindings file binds scenario steps to code functions that implement the steps. The YAML file is a list of objects (also known as dicts or hashmaps or key/value pairs), specifying a step kind (given, when, then), a pattern matching the text of the step and optionally capturing interesting parts of the text. Each binding may contain a type map which tells subplot the types of the captures in the patterns so that they can be validated to some extent, and a binding will list some number of implementations, each of which is specified by the name of the language (template) it is for, and then the name of a function that implements the step, optionally with the name of a function to call to clean up a scenario which includes that step.

There are some flexibilities in bindings, futher details can be found below:

1. Patterns can be simple or full-blown Perl-compatible regular expresssions (PCRE).
2. Bindings may have type maps. Without a type map, all captures are considered to be short strings (words).
3. Bindings may have as many or as few implementations as needed. A zero impl binding will work for docgen but will fail to codegen. This can permit document authors to prepare bindings without knowing how an engineer might implement it.

- given: "a standard setup"
  impl:
    python:
      function: create_standard_setup
- when: "{thing} happens"
  impl:
    python:
      function: make_thing_happen
  types:
    thing: word
- when: "I say (?P<sentence>.+) with a smile"
  regex: true
  impl:
    python:
      function: speak
- then: "everything is OK"
  impl:
    python:
      function: check_everything_is_ok

In the example above, there are four bindings and they all provide Python implementation functions:

• A binding for a "given a standard setup" step. The binding captures no part of the text, and causes the create_standard_setup function to be called.
• A binding for a "when" step consisting of one word followed by "happens". For example, "peace", as in "then peace happens". The word is captured as "thing", and given to the make_thing_happen function as an argument when it is called.
• A binding for a "when" followed by "I say", an arbitrary sentence, and then "with a smile", as in "when I say good morning to you with a smile". The function speak is then called with capture named "sentence" as "good morning to you".
• A binding for a "then everything is OK" step, which captures nothing, and calls the check_everything_is_ok function.

Step functions and cleanup

A step function must be atomic: either it completes successfully, or it cleans up any changes it made before returning an indication of failure.

A cleanup function is only called for successfully executed step functions.

For example, consider a step that creates and starts a virtual machine. The step function creates the VM, then starts it, and if both actions succeeds, the step succeeds. A cleanup function for that step will stop and delete the VM. The cleanup is only called if the step succeeded. If the step function manages to create the VM, but not start it, it's the step function's responsibility to delete the VM, before it signals failure. The cleanup function won't be called in that case.

Simple patterns

The simple patterns are of the form {name} and match a single word consisting of printable characters. This can be varied by adding a suffix, such as {name:text} which matches any text. The following kinds of simple patterns are supported:

• {name} or {name:word} – a single word. As a special case, the form {name:file} is also supported. It is also a single word, but has the added constraint that it must match an embedded file's name.
• {name:text} – any text
• {name:int} – any whole number, including negative
• {name:uint} – any unsigned whole number
• {name:number} – any number

A pattern uses simple patterns by default, or if the regex field is set to false. To use regular expressions, regex must be set to true. Subplot complains if typical regular expression characters are used, when simple patterns are expected, unless regex is explicitly set to false.

Regular expression patterns

Regular expression patterns are used only if the binding regex field is set to true.

The regular expressions use PCRE syntax as implemented by the Rust regex crate. The (?P<name>pattern) syntax is used to capture parts of the step. The captured parts are given to the bound function as arguments, when it's called.

The type map

Bindings may also contain a type map. This is a dictionary called types and contains a key-value mapping from capture name to the type of the capture. Valid types are listed above in the simple patterns section. In addition to simple patterns, the type map can be used for regular expression bindings as well.

When using simple patterns, if the capture is given a type in the type map, and also in the pattern, then the types must match, otherwise subplot will refuse to load the binding.

Typically the type map is used by the code generators to, for example, distinguish between "12" and 12 (i.e. between a string and what should be a number). This permits the generated test suites to use native language types directly. The file type, if used, must refer to an embedded file in the document; subplot docgen will emit a warning if the file is not found, and subplot codegen will emit an error.

The implementation map

Bindings can contain an impl map which connects the binding with zero or more language templates. If a binding has no impl entries then it can still be used to docgen a HTML document from a subplot document. This permits a workflow where requirements owners / architects design the validations for a project and then engineers implement the step functions to permit the validations to work.

Shipped with subplot are a number of libraries such as files or runcmd and these libraries are polyglot in that they provide bindings for all supported templates provided by subplot.

Here is an example of a binding from one of those libraries:

- given: file {embedded_file}
  impl:
    rust:
      function: subplotlib::steplibrary::files::create_from_embedded
    python:
      function: files_create_from_embedded
  types:
    embedded_file: file

Embedded file name didn't match

title: Bad filenames in matched steps do not permit codegen
markdowns: [badfilename.md]
bindings: [b.yaml]
impls:
  python: [f.py]

# Bad filename

```scenario
given file missing.md
```

Bindings file strictness - given when then

The bindings file is semi-strict. For example you must have only one of given, when, or then in your binding.

title: Bad bindings cause everything to fail
markdowns: [badbindingsgwt.md]
bindings: [badbindingsgwt.yaml]

# Bad bindings
```scenario
given we won't reach here
```

- given: we won't reach here
  then: we won't reach here

Bindings file strictness - unknown field

The bindings file is semi-strict. For example, you must not have keys in the bindings file which are not known to Subplot.

title: Bad bindings cause everything to fail
markdowns: [badbindingsuf.md]
bindings: [badbindingsuf.yaml]

# Bad bindings
```scenario
given we won't reach here
```

- given: we won't reach here
  function: old_school_function

Functions file

Functions implementing steps are supported in Bash and Python. The language is chosen by setting the template field in the document YAML metadata to bash or python.

The functions files are not parsed by Subplot at all. Subplot merely copies them to the output. All parsing and validation of the file is done by the programming language being used.

The conventions for calling step functions vary by language. All languages support a "dict" abstraction of some sort. This is most importantly used to implement a "context" to store state in a controlled manner between calls to step functions. A step function can set a key to a value in the context, or retrieve the value for a key.

Typically, a "when" step does something, and records the results into the context, and a "then" step checks the results by inspecting the context. This decouples functions from each other, and avoids having them use global variables for state.

Bash

The step functions are called without any arguments.

The context is managed using shell functions provided by the Bash template:

• ctx_set key value
• ctx_get key

Captured values from scenario steps are passed in via another dict and accessed using another function:

• cap_get key

Similarly, there's a dict for the contents of embedded data files:

• files_get filename

The template provides assertion functions: assert_eq, assert_contains.

Example:

_run()
{
    if "$@" < /dev/null > stdout 2> stderr
    then
        ctx_set exit 0
    else
        ctx_set exit "$?"
    fi
    ctx_set stdout "$(cat stdout)"
    ctx_set stderr "$(cat stderr)"
}

run_echo_without_args()
{
    _run echo
}

run_echo_with_args()
{
    args="$(cap_get args)"
    _run echo "$args"
}

exit_code_is()
{
    actual_exit="$(ctx_get exit)"
    wanted_exit="$(cap_get exit_code)"
    assert_eq "$actual_exit" "$wanted_exit"
}

stdout_is_a_newline()
{
    stdout="$(ctx_get stdout)"
    assert_eq "$stdout" "$(printf '\n')"
}

stdout_is_text()
{
    stdout="$(ctx_get stdout)"
    text="$(cap_get text)"
    assert_contains "$stdout" "$text"
}

stderr_is_empty()
{
    stderr="$(ctx_get stderr)"
    assert_eq "$stderr" ""
}

Python

The context is implemented by a dict-like class.

The step functions are called with a ctx argument that has the current state of the context, and each capture from a step as a keyword argument. The keyword argument name is the same as the capture name in the pattern in the bindings file.

The contents of embedded files are accessed using a function:

• get_file(filename)

Example:

import json

def exit_code_is(ctx, wanted=None):
    assert_eq(ctx.get("exit"), wanted)

def json_output_matches_file(ctx, filename=None):
    actual = json.loads(ctx["stdout"])
    expected = json.load(open(filename))
    assert_dict_eq(actual, expected)

def file_ends_in_zero_newlines(ctx, filename=None):
    content = open(filename, "r").read()
    assert_ne(content[-1], "\n")

Comparing the scenario runners

Currently Subplot ships with three scenario runner templates. The Bash, Python, and Rust templates. The first two are fully self-contained and have a set of features dictated by the Subplot version. The latter is tied to how Cargo runs tests. Given that, this comparison is only considered correct against the version of Rust at the time of publishing a Subplot release. Newer versions of Rust may introduce additional functionality which we do not list here. Finally, we do not list features here which are considered fundamental, such as "runs all the scenarios" or "supports embedded files" since no template would be considered for release if it did not do these things. These are the differentiation points.

| Feature                       | Bash                                     | Python                                         | Rust                                                         |
| ----------------------------- | ---------------------------------------- | ---------------------------------------------- | ------------------------------------------------------------ |
| Isolation model               | Subprocess                               | Subprocess                                     | Threads                                                      |
| Parallelism                   | None                                     | None                                           | Threading                                                    |
| Passing environment variables | CLI                                      | CLI                                            | Prefixed env vars                                            |
| Execution order               | Fixed order                              | Randomised                                     | Fixed order plus threading peturbation                       |
| Run specific scenarios        | Simple substring check                   | Simple substring check                         | Either exact _or_ simple substring check                     |
| Diagnostic logging            | Writes to stdout/stderr per normal shell | Supports comprehensive log file                | Writes captured output to stdout/stderr on failure           |
| Stop-on-failure               | Stops on first failure                   | Stops on first failure unless told not to      | Runs all tests unless told not to                            |
| Data dir integration          | Cleans up only on full success           | Cleans up each scenario unless told to save it | Cleans up each scenario with no option to save failure state |

Acceptance criteria for Subplot

Add the acceptance criteria test scenarios for Subplot here.

Test data shared between scenarios

The 'smoke-test' scenarios below test Subplot by running it against specific input files. This section specifies the bindings and functions files, which are generated and cleaned up on the fly. They're separate from the scenarios so that the scenarios are shorter and clearer, but also so that the input files do not need to be duplicated for each scenario.

title: Test scenario
markdowns:
- simple.md
bindings: [b.yaml]
impls:
  python: [f.py]

# Simple
This is the simplest possible test scenario

```scenario
given precondition foo
when I do bar
then bar was done
```

- given: precondition foo
  impl:
    python:
      function: precond_foo
    bash:
      function: precond_foo
- when: I do bar
  impl:
    python:
      function: do_bar
    bash:
      function: do_bar
- when: I do foobar
  impl:
    python:
      function: do_foobar
    bash:
      function: do_foobar
- then: bar was done
  impl:
    python:
      function: bar_was_done
    bash:
      function: bar_was_done
- then: foobar was done
  impl:
    python:
      function: foobar_was_done
    bash:
      function: foobar_was_done
- given: file {filename}
  impl:
    python:
      function: provide_file
    bash:
      function: provide_file
  types:
    filename: file

def precond_foo(ctx):
    ctx['bar_done'] = False
    ctx['foobar_done'] = False
def do_bar(ctx):
    ctx['bar_done'] = True
def bar_was_done(ctx):
    assert_eq(ctx['bar_done'], True)
def do_foobar(ctx):
    ctx['foobar_done'] = True
def foobar_was_done(ctx):
    assert_eq(ctx['foobar_done'], True)

Smoke test

The scenario below uses the input files defined above to run some tests to verify that Subplot can build an HTML document, and execute a simple scenario successfully. The test is based on generating the test program from an input file, running the test program, and examining the output.

Indented scenario steps are not allowed

Requirement: A scenario step starts at the beginning of the line.

Justification: We may want to allow continuing a step to the next line, but as of June, 2023, we haven't settled on a syntax for this. However, whatever syntax we do eventually choose, it will be easier to add that if scenario steps start at the beginning of a line, without making a breaking change.

title: Indented scenario step
markdowns:
  - indented-step.md
bindings:
  - b.yaml

# This is a title

~~~scenario
  given precondition
~~~

Named code blocks must have an appropriate class

Requirement: Named code blocks must carry an appropriate class such as file or example

Justification: Eventually we may want to add other meanings to named blocks, currently the identifier cannot be used except to refer to the block as a named file, but we may want to in the future so this is here to try and prevent any future incompatibilities.

title: Named code blocks carry appropriate classes step
markdowns:
  - named-code-blocks-appropriate.md
bindings:
  - b.yaml

# This is a title

~~~scenario
given precondition
~~~

~~~{#example-1 .numberLines}
This example is bad
~~~

~~~{#example-2 .file .numberLines}
This example is OK because of .file
~~~

~~~{#example-3 .example .numberLines}
This example is OK because of .example
~~~

No scenarios means codegen fails

If you attempt to subplot codegen on a document which contains no scenarios, the tool will fail to execute with a reasonable error message.

title: No scenarios in here
markdowns: [noscenarios.md]
impls: { python: [] }

# This is a title

But there are no scenarios in this file, and thus nothing can be generated in a test suite.

No template means you can docgen but not codegen

When running docgen you do not need a template to have been defined in the subplot input document. If you have template-specific bindings then you should provide one, but if not, then it is unnecessary. This means you can use docgen to build documents before you have any inkling of the implementation language necessary to validate the scenarios.

title: No templates in here
markdowns: [notemplate.md]
impls: { }

# This is a title

```scenario
then failure ensues
```

Keywords

Subplot supports the keywords given, when, and then, and the aliases and and but. The aliases stand for the same (effective) keyword as the previous step in the scenario. This chapter has scenarios to check the keywords and aliases in various combinations.

All the keywords

title: All the keywords scenario
markdowns:
- allkeywords.md
bindings: [b.yaml]
impls:
  python: [f.py]

# All keywords

This uses all the keywords.

```scenario
given precondition foo
when I do bar
and I do foobar
then bar was done
but foobar was done
```

Misuse of continuation keywords

When continuation keywords (and and but) are used, they have to not be the first keyword in a scenario. Any such scenario will fail to parse because subplot will be unable to determine what kind of keyword they are meant to be continuing.

title: Continuation keyword misuse
markdowns:
- continuationmisuse.subplot
bindings: [b.yaml]
impls:
  python: [f.py]

# Continuation keyword misuse

This scenario should fail to parse because we misuse a
continuation keyword at the start.

```scenario
and precondition foo
when I do bar
then bar was done
```

Title markup

It is OK to use markup in document titles, in the YAML metadata section. This scenario verifies that all markup works.

title: This _uses_ ~~all~~ **most** inline `markup`
subtitle: H~2~O is not 2^10^
markdowns: [title-markup.md]
impls: { python: [] }

# Introduction

Scenario titles

A scenario gets its title from the lowest level of section heading that applies to it. The heading can use markup.

title: Test scenario
markdowns:
- scenario-titles.md
bindings: [b.yaml]
impls:
  python: [f.py]

# My **fun** _scenario_ `title`

```scenario
given precondition foo
when I do bar
then bar was done
```

Duplicate scenario titles

Requirement: Subplot treats it as an error if two scenarios have the same title.

Justification: the title is how a scenario is identified, and the user needs to be able to do so unambiguously.

title: Test scenario
markdowns:
- duplicate-scenario-titles.md
bindings: [b.yaml]
impls:
  python: [f.py]

# My sceanrio

```scenario
when I do bar
```

# My sceanrio

```scenario
when I do bar
```

Empty lines in scenarios

This scenario verifies that empty lines in scenarios are OK.

title: Test scenario
markdowns:
- emptylines.md
bindings: [b.yaml]
impls:
  python: [f.py]

# Simple
This is the simplest possible test scenario

```scenario
given precondition foo

when I do bar

then bar was done

```

Automatic cleanup in scenarios

A binding can define a cleanup function, which gets called at the end of the scenario in reverse order for the successful steps. If a step fails, all the cleanups for the successful steps are still called. We test this for every language template we support.

- given: foo
  impl:
    python:
      function: foo
      cleanup: foo_cleanup
    bash:
      function: foo
      cleanup: foo_cleanup
- given: bar
  impl:
    python:
      function: bar
      cleanup: bar_cleanup
    bash:
      function: bar
      cleanup: bar_cleanup
- given: failure
  impl:
    python:
      function: failure
      cleanup: failure_cleanup
    bash:
      function: failure
      cleanup: failure_cleanup

def foo(ctx):
   pass
def foo_cleanup(ctx):
   pass
def bar(ctx):
   pass
def bar_cleanup(ctx):
   pass
def failure(ctx):
   assert 0
def failure_cleanup(ctx):
   pass

foo() {
    true
}
foo_cleanup() {
    true
}
bar() {
    true
}
bar_cleanup() {
    true
}
failure() {
   return 1
}
failure_cleanup() {
   true
}

Cleanup functions gets called on success (Python)

title: Cleanup
markdowns:
- cleanup-success-python.md
bindings: [cleanup.yaml]
impls:
  python: [cleanup.py]

# Cleanup

~~~scenario
given foo
given bar
~~~

Cleanup functions get called on failure (Python)

title: Cleanup
markdowns:
- cleanup-fail-python.md
bindings: [cleanup.yaml]
impls:
  python: [cleanup.py]

# Cleanup

~~~scenario
given foo
given bar
given failure
~~~

Cleanup functions gets called on success (Bash)

title: Cleanup
markdowns:
- cleanup-success-bash.md
bindings: [cleanup.yaml]
impls:
  bash: [cleanup.sh]

---
title: Cleanup
bindings: [cleanup.yaml]
impls:
  bash: [cleanup.sh]
...

# Cleanup

~~~scenario
given foo
given bar
~~~

Cleanup functions get called on failure (Bash)

If a step fails, all the cleanups for the preceding steps are still called, in reverse order.

title: Cleanup
markdowns:
- cleanup-fail-bash.md
bindings: [cleanup.yaml]
impls:
  bash: [cleanup.sh]

# Cleanup

~~~scenario
given foo
given bar
given failure
~~~

Temporary files in scenarios in Python

The Python template for generating test programs supports the --save-on-failure option. If the test program fails, it produces a dump of the data directories of all the scenarios it has run. Any temporary files created by the scenario using the usual mechanisms need to be in that dump. For this to happen, the test runner must set the TMPDIR environment variable to point at the data directory. This scenario verifies that it happens.

title: TMPDIR
markdowns: [tmpdir.md]
bindings: [tmpdir.yaml]
impls:
  python: [tmpdir.py]

# TMPDIR

~~~scenario
then TMPDIR is set
~~~

- then: TMPDIR is set
  impl:
    python:
      function: tmpdir_is_set

import os
def tmpdir_is_set(ctx):
	assert_eq(os.environ.get("TMPDIR"), os.getcwd())

Capturing parts of steps for functions

A scenario step binding can capture parts of a scenario step, to be passed to the function implementing the step as an argument. Captures can be done using regular expressions or "simple patterns".

Capture using simple patterns

title: Simple pattern capture
markdowns:
- simplepattern.md
bindings: [simplepattern.yaml]
impls:
  python: [capture.py]

# Simple pattern

~~~scenario
given I am Tomjon
~~~

- given: I am {name}
  impl:
    python:
      function: func

def func(ctx, name=None):
    print('function got argument name as', name)

Simple patterns with regex metacharacters: forbidden case

Help users to avoid accidental regular expression versus simple pattern confusion. The rule is that a simple pattern mustn't contain regular expression meta characters unless the rule is explicitly marked as not being a regular expression pattern.

title: Simple pattern capture
markdowns:
- confusedpattern.md
bindings: [confusedpattern.yaml]
impls:
  python: [capture.py]

# Simple pattern

~~~scenario
given I* am Tomjon
~~~

- given: I* am {name}
  impl:
    python:
      function: func

Simple patterns with regex metacharacters: allowed case

title: Simple pattern capture
markdowns:
- confusedbutok.md
bindings: [confusedbutok.yaml]
impls:
  python: [capture.py]

# Simple pattern

~~~scenario
given I* am Tomjon
~~~

- given: I* am {name}
  impl:
    python:
      function: func
  regex: false

Capture using regular expressions

title: Regex capture
markdowns:
- regex.md
bindings: [regex.yaml]
impls:
  python: [capture.py]

# Regex

~~~scenario
given I am Tomjon
~~~

- given: I am (?P<name>\S+)
  impl:
    python:
      function: func
  regex: true

Recall values for use in later steps

It's sometimes useful to use a value remembered in a previous step. For example, if one step creates a resource with a random number as its name, a later step should be able to use it. This happens in enough projects that Subplot's Python template has support for it.

The Python template has a Context class, with methods remember_value, recall_value, and expand_values. These values are distinct from the other values that can be stored in a context. Only explicitly remembered values may be recalled or expanded so that expansions don't accidentally refer to values meant for another purpose.

title: Values
markdowns:
- values.md
bindings: [values.yaml]
impls:
  python: [values.py]

# Values

~~~scenario
when I remember foo as bar
then expanded "${foo}" is bar
~~~

- when: I remember {name} as {value}
  impl:
    python:
      function: remember

- then: expanded "{actual}" is {expected}
  impl:
    python:
      function: check

def remember(ctx, name=None, value=None):
	ctx.remember_value(name, value)

def check(ctx, expected=None, actual=None):
    assert_eq(ctx.expand_values(actual), expected)

Set environment variables in generated test programs

The generated test programs run each scenario with a fixed, almost empty set of environment variables. This is so that tests are more repeatable and less dependent on any values accidentally set by the developers.

However, sometimes it's helpful for the user to be able to set environment variables for the scenarios. For example, if the scenarios test locally built binaries that may be installed anywhere, the installation directory should be added to the PATH variable so that scenarios can invoke the scripts easily.

The scenario in this section verifies that the Python test program generated by subplot codegen accepts the option --env NAME=VALUE.

There is currently no equivalent functionality for the generated Bash test program. Patches for that are welcome.

title: Environment variables
markdowns:
- env.md
bindings: [env.yaml]
impls:
  python: [env.py]

# Test
~~~scenario
then environment variable FOO is set to "bar"
~~~

- then: environment variable {name} is set to "{value:text}"
  impl:
    python:
      function: is_set_to

import os, sys
def is_set_to(ctx, name=None, value=None):
  sys.stderr.write(f"{name}={os.environ.get(name)!r}\n")
  assert os.environ.get(name) == value

Document structure

Subplot uses chapters and sections to keep together scenario snippets that form a complete scenario. The lowest level heading before a snippet starts a scenario and is the name of the scenario. If there are subheadings, they divide the description of the scenario into parts, but don't start a new scenario. The next heading at the same or a higher level starts a new scenario.

Lowest level heading is name of scenario

title: Test scenario
markdowns:
- scenarioislowest.md
bindings: [b.yaml]
impls:
  python: [f.py]

# heading 1
## heading 1.1
### heading 1.1.1

```scenario
given precondition foo
```

Subheadings don't start new scenario

title: Test scenario
markdowns:
- subisnotnewscenario.md
bindings: [b.yaml]
impls:
  python: [f.py]

# heading 1
## heading 1.1a

```scenario
given precondition foo
```

### heading 1.1.1
### heading 1.1.2

Next heading at same level starts new scenario

title: Test scenario
markdowns:
- samelevelisnewscenario.md
bindings: [b.yaml]
impls:
  python: [f.py]

# heading 1
## heading 1.1
### heading 1.1.1

```scenario
given precondition foo
```
### heading 1.1.2

```scenario
given precondition foo
```

Next heading at higher level starts new scenario

title: Test scenario
markdowns:
- higherisnewscenario.md
bindings: [b.yaml]
impls:
  python: [f.py]

# heading 1
## heading 1.1
### heading 1.1.1

```scenario
given precondition foo
```
## heading 1.2

```scenario
given precondition foo
```

Document titles

The document and code generators require a document title, because it's a common user error to not have one, and Subplot should help make good documents.

Document generator gives an error if input document lacks title

markdowns:
- notitle.md
bindings: [b.yaml]
functions: [f.py]

# Introduction

This is a very simple Markdown file without a document title.

```scenario
given precondition foo
when I do bar
then bar was done

Code generator gives an error if input document lacks title

Subplot accepts title and headings with inline markup

Markdown allows using any inline markup in document titles and chapter and section headings. Verify that Subplot accepts them.

title: Plain *emph* **strong** ~~strikeout~~ superscript^10^ subscript~10~
markdowns:
- fancytitle.md
bindings: [b.yaml]
impls:
  python: [f.py]

# `code` [smallcaps]{.smallcaps} $$2^10$$

## "double quoted"
## 'single quoted'
## <b>raw inline</b>
## <span>span</span>
## ![alt](image.jpg)
## footnote[^1]

[^1]: footnote

This is a very simple Markdown file that uses every kind of inline
markup in the title and chapter heading.

To satisfy codegen, we *MUST* have a scenario here

~~~~scenario
when I do bar
then bar was done
~~~~

Running only chosen scenarios

To make the edit-test loop more convenient for the test programs generated by Subplot, we allow the user to specify patterns for scenarios to run. Default is to run all scenarios.

Running only chosen scenarios with Python

This verifies that the generated Python test program can run only chosen scenarios.

title: Test scenario
markdowns:
- twoscenarios-python.md
bindings: [b.yaml]
impls:
  python: [f.py]

# One

```scenario
given precondition foo
when I do bar
then bar was done
```

# Two

```scenario
given precondition foo
when I do bar
then bar was done
```

Running only chosen scenarios with Bash

This verifies that the generated Bash test program can run only chosen scenarios.

title: Test scenario
markdowns:
- twoscenarios-bash.md
bindings: [b.yaml]
impls:
  bash: [f.sh]

# One

```scenario
given precondition foo
when I do bar
then bar was done
```

# Two

```scenario
given precondition foo
when I do bar
then bar was done
```

precond_foo() {
    ctx_set bar_done 0
    ctx_set foobar_done 0
}

do_bar() {
    ctx_set bar_done 1
}

do_foobar() {
    ctx_set foobar_done 1
}

bar_was_done() {
    actual="$(ctx_get bar_done)"
    assert_eq "$actual" 1
}

foobar_was_done() {
    actual="$(ctx_get foobar_done)"
    assert_eq "$actual" 1
}

Document metadata

Some document metadata should end up in the typeset document, especially the title, authors. The document date is more complicated, to cater to different use cases:

• a work-in-progress document needs a new date for each revision
  • maintaining the date metadata field manually is quite tedious, so Subplot provides it automatically using the document source file modification time
  • some people would prefer a git describe or similar method for indicating the document revision, so Subplot allows the date to be specified via the command line
• a finished, reviewed, officially stamped document needs a fixed date
  • Subplot allows this to be written as the date metadata field

The rules for what Subplot uses as the date or document revision information are, then:

• if there is date metadata field, that is used
• otherwise, if the user gives the --date command line option, that is used
• otherwise, the markdown file's modification time is used

Date given in metadata

This scenario tests that the date field in metadata is used if specified.

title: The Fabulous Title
authors:
- Alfred Pennyworth
- Geoffrey Butler
date: WIP
markdowns:
- metadate.md

# Introduction
This is a test document. That's all.

Date given on command line

This scenario tests that the --date command line option is used.

title: The Fabulous Title
authors:
- Alfred Pennyworth
- Geoffrey Butler
markdowns:
- dateless.md

# Introduction
This is a test document. It has no date metadata.

No date anywhere

This scenario tests the case of no metadata date and no command line option, either. The date in the typeset document shall come from the modification time of the input file, and shall have the date in ISO 8601 format, with time to the minute.

Missing bindings file

If a bindings file is missing, the error message should name the missing file.

title: Missing binding
markdowns:
- missing-binding.md
bindings: [missing-binding.yaml]

Missing functions file
If a functions file is missing, the error message should name the
missing file.

given file missing-functions.subplot
given file missing-functions.md
given file b.yaml
given an installed subplot
when I try to run subplot codegen --run missing-functions.subplot -o foo.py
then command fails
then stderr contains "could not be found"
then stderr contains "missing-functions.py"
---
title: Missing functions
markdowns:
- missing-functions.md
bindings: [b.yaml]
impls:
  python: [missing-functions.py]
...
Extracting metadata from a document
The subplot metadata program extracts metadata from a document. It is
useful to see the scenarios, for example. For example, given a
document like this:
subplot metadata would extract this information from the simple.md example:
title: Test scenario
bindings: [b.yaml]
impls:
  python: [f.py]
scenario Simple

This scenario check subplot metadata works. Note that it requires the bindings
or functions files.

given file images.subplot
given file images.md
given file b.yaml
given file other.yaml
given file f.py
given file other.py
given file expected.json
given an installed subplot
when I run subplot metadata images.subplot
then stdout contains "source: images.md"
then stdout contains "source: b.yaml"
then stdout contains "source: other.yaml"
then stdout contains "source: f.py"
then stdout contains "source: other.py"
then stdout contains "source: image.gif"
then stdout contains "bindings: b.yaml"
then stdout contains "bindings: other.yaml"
then stdout contains "functions[python]: f.py"
when I run subplot metadata images.subplot -o json
then JSON output matches expected.json
title: Document refers to external images
markdowns:
- images.md
bindings:
- b.yaml
- other.yaml
impls:
  python:
    - f.py
    - other.py
![alt text](image.gif)
[]
{
	"title": "Document refers to external images",
    "sources": [
	  "b.yaml",
	  "f.py",
	  "image.gif",
	  "images.md",
      "images.subplot",
	  "other.py",
	  "other.yaml"
    ],
	"binding_files": [
	  "b.yaml",
	  "other.yaml"
	],
	"impls": {
    "python": [
	    "f.py",
	    "other.py"
	  ]
  },
	"files": [],
	"scenarios": []
}

Multiple markdown files
This scenario tests that the markdowns field in metadata can specify
more than one markdown file.

given file multimd.subplot
given file md1.md
given file md2.md
given an installed subplot
when I run subplot docgen multimd.subplot -o multimd.html
when I run cat multimd.html
then file multimd.html exists
then file multimd.html contains "<title>The Fabulous Title</title>"
then file multimd.html contains "First markdown file."
then file multimd.html contains "Second markdown file."
title: The Fabulous Title
authors:
- Alfred Pennyworth
- Geoffrey Butler
date: WIP
markdowns:
- md1.md
- md2.md
First markdown file.
Second markdown file.

Embedded files
Subplot allows data files to be embedded in the input document. This
is handy for small test files and the like.
Handling of a newline character on the last line is tricky. The block
ends in a newline on the last line. Sometimes one is needed—but
sometimes it's not wanted. Subplot helps the situation by allowing a
add-newline= class to be added to the code blocks, with one of three
allowed cases:

no add-newline class—default handling: same as add-newline=auto
add-newline=auto—add a newline, if one isn't there
add-newline=no—never add a newline, but keep one if it's there
add-newline=yes—always add a newline, even if one is already
there
The scenarios below test the various cases.
Extract embedded file
This scenario checks that an embedded file can be extracted, and used
in a subplot.

given file embedded.subplot
given file embedded.md
given an installed subplot
when I run subplot docgen --merciful embedded.subplot -o foo.html
then file foo.html exists
then file foo.html matches regex /embedded\.txt/
title: One embedded file
markdowns:
- embedded.md
~~~{#embedded.txt .file}
This is the embedded file.
~~~

Extract embedded file, by default add missing newline
This scenario checks the default handling: add a newline if one is
missing.

given file default-without-newline.txt
then default-without-newline.txt ends in one newline
This file does not end in a newline.

Extract embedded file, by default do not add a second newline
This scenario checks the default handling: if content already ends in
a newline, do not add another newline.

given file default-has-newline.txt
then default-has-newline.txt ends in one newline
This file ends in a newline.


Extract embedded file, automatically add missing newline
Explicitly request automatic newlines, when the file does not end in
one.

given file auto-without-newline.txt
then auto-without-newline.txt ends in one newline
This file does not end in a newline.

Extract embedded file, do not automatically add second newline
Explicitly request automatic newlines, when the file already ends in
one.

given file auto-has-newline.txt
then auto-has-newline.txt ends in one newline
This file ends in a newline.


Extract embedded file, explicitly add missing newline
Explicitly request automatic newlines, when the file doesn't end with
one.

given file add-without-newline.txt
then add-without-newline.txt ends in one newline
This file does not end in a newline.

Extract embedded file, explicitly add second newline
Explicitly request automatic newlines, when the file already ends with
one.

given file add-has-newline.txt
then add-has-newline.txt ends in two newlines
This file ends in a newline.


Extract embedded file, do not add missing newline
Explicitly ask for no newline to be added.

given file no-adding-without-newline.txt
then no-adding-without-newline.txt does not end in a newline
This file does not end in a newline.

Fail if the same filename is used twice

given file onefiletwice.md
given an installed subplot
when I try to run subplot docgen onefiletwice.md -o onefiletwice.html
then command fails
then file onefiletwice.html does not exist
---
title: Two embedded files with the same name
...

```{#filename .file}
This is the embedded file.
```

```{#filename .file}
This is another embedded file, and has the same name.
```

Fail if two filenames only differ in case

given file casediff.md
given an installed subplot
when I try to run subplot docgen casediff.md -o casediff.html
then command fails
then file casediff.html does not exist
---
title: Two embedded files with names differing only in case
...

```{#filename .file}
This is the embedded file.
```

```{#FILENAME .file}
This is another embedded file, and has the same name in uppercase.
```

Fail if embedded file isn't used
This scenario checks that we get warnings, when using a subplot with
embedded files that aren't used.

given file unusedfile.subplot
given file unusedfile.md
given an installed subplot
when I try to run subplot docgen --merciful unusedfile.subplot -o unusedfile.html
then command is successful
then file unusedfile.html exists
then stderr contains "thisisnotused.txt"
title: Embedded file is not used by a scenario
markdowns:
- unusedfile.md
```{#thisisnotused.txt .file}
This is the embedded file.
```

Example blocks
Similar to embedded files, Subplot permits you to mark blocks as examples.
Example blocks are formatted just like file blocks, but they may not be
used by scenarios and their names are separated from files, and are not
subject to the same naming constraints (caseless uniqueness).
Examples may be unused

given file unusedexample.subplot
given file unusedexample.md
given an installed subplot
when I try to run subplot docgen --merciful unusedexample.subplot -o unusedexample.html
then command is successful
then file unusedexample.html exists
then stderr doesn't contain "thisisnotused.txt"
title: Example is not an embedded file
markdowns:
- unusedexample.md
```{#thisisnotused.txt .example}
This is the embedded example.
```

Examples are not files

given file examplesnotfiles.subplot
given file examplesnotfiles.md
given an installed subplot
when I try to run subplot codegen examplesnotfiles.subplot -t python -o examplesnotfiles.html
then command fails
then file examplesnotfiles.html does not exist
then stderr contains "thisisanexample.txt"
title: Examples are not files
markdowns:
- examplesnotfiles.md
impls:
  python: []
# Try and use an example as a file

```scenario
given file thisisanexample.txt
```

```{#thisisanexample.txt .example}
This is an embedded example
```

Steps must match bindings
Subplot permits the binding author to define arbitrarily complex regular
expressions for binding matches.  In order to ensure that associating steps
to bindings is both reliable and tractable, a step must match exactly one
binding.
- given: a binding
  impl:
    python:
      function: a_binding
- given: a (?:broken)? binding
  impl:
    python:
      function: a_broken_binding
  regex: true
- given: a capitalised Binding
  impl:
    python:
      function: os.getcwd
  case_sensitive: true

Steps which do not match bindings do not work
title: No bindings available
markdowns:
- nobinding.md
bindings:
- badbindings.yaml
# Broken scenario because step has no binding

```scenario
given a missing binding
then nothing works
```


given file nobinding.subplot
given file nobinding.md
given file badbindings.yaml
given an installed subplot
when I try to run subplot codegen --run nobinding.subplot -o test.py
then command fails
Steps which do not case-sensitively match sensitive bindings do not work
title: Case sensitivity mismatch
markdowns:
- casemismatch.md
impls: { python: [] }
bindings:
- badbindings.yaml
# Broken scenario because step has a case mismatch with sensitive binding

```scenario
given a capitalised binding
```


given file casemismatch.subplot
given file casemismatch.md
given file badbindings.yaml
given an installed subplot
when I try to run subplot codegen --run casemismatch.subplot -o test.py
then command fails
Steps which match more than one binding do not work
title: Two bindings match
markdowns:
- twobindings.md
bindings:
- twobindings.yaml
impls:
  python: [a_function.py]
# Broken scenario because step has two possible bindings

```scenario
given a binding
```
- given: a {xyzzy}
  impl:
    python:
      function: a_function
- given: a {plugh}
  impl:
    python:
      function: a_function
def a_function(ctx):
    assert 0


given file twobindings.subplot
given file twobindings.md
given file twobindings.yaml
given file a_function.py
given an installed subplot
when I try to run subplot codegen --run twobindings.subplot -o test.py
then command fails
then stderr contains "xyzzy"
then stderr contains "plugh"
List embedded files
The subplot metadata command lists embedded files in its output.

given file two-embedded.subplot
given file two-embedded.md
given an installed subplot
when I run subplot metadata --merciful two-embedded.subplot
then stdout contains "foo.txt"
then stdout contains "bar.yaml"
title: Two embedded files
markdowns:
- two-embedded.md
~~~{#foo.txt .file}
~~~

~~~{#bar.yaml. .file}
~~~

Embedded diagrams
Subplot allows embedding markup to generate diagrams into the Markdown document.
Pikchr
Pikchr is a diagramming library which implements a Pic-like diagram language.
It allows the conversion of textual descriptions of arbitrarily complex diagrams
into SVGs such as this one.

The scenario checks that a diagram is generated and embedded into the HTML output,
and is not referenced as an external image.

given file pikchr.subplot
given file pikchr.md
given an installed subplot
when I run subplot docgen pikchr.subplot -o pikchr.html
then file pikchr.html matches regex /src="data:image/svg\+xml;base64,/
The sample input file pikchr.md:
---
This is an example markdown file that embeds a simple Pikchr diagram.

~~~pikchr
arrow right 200% "Markdown" "Source"
box rad 10px "Markdown" "Formatter" "(docs.rs/markdown)" fit
arrow right 200% "HTML+SVG" "Output"
arrow <-> down 70% from last box.s
box same "Pikchr" "Formatter" "(docs.rs/pikchr)" fit
~~~

title: Pikchr test
markdowns:
- pikchr.md

Dot
Dot is a program from the Graphviz suite to generate directed
diagrams, such as this one.

The scenario checks that a diagram is generated and embedded into the
HTML output, not referenced as an external image.

given file dot.subplot
given file dot.md
given file b.yaml
given an installed subplot
when I run subplot docgen dot.subplot -o dot.html
then file dot.html matches regex /src="data:image/svg\+xml;base64,/
The sample input file dot.md:
This is an example Markdown file, which embeds a diagram using dot markup.

~~~dot
digraph "example" {
thing -> other
}
~~~
title: Dot test
markdowns:
- dot.md

PlantUML
PlantUML is a program to generate various kinds of diagrams for
describing software, such as this one:

The scenario below checks that a diagram is generated and embedded into
the HTML output, not referenced as an external image.

given file plantuml.subplot
given file plantuml.md
given file b.yaml
given an installed subplot
when I run subplot docgen plantuml.subplot -o plantuml.html
then file plantuml.html matches regex /src="data:image/svg\+xml;base64,/
The sample input file plantuml.md:
This is an example Markdown file, which embeds a diagram using
PlantUML markup.

~~~plantuml
@startuml
Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response

Alice -> Bob: Another authentication Request
Alice <-- Bob: Another authentication Response
@enduml
~~~
title: Plantuml test
markdowns:
- plantuml.md

Roadmap
Subplot supports visual roadmaps using a YAML based markup language,
implemented by the roadmap Rust library. The library converts the
roadmap into dot, and that gets rendered as SVG and embedded in the
output document by Subplot.
An example:

This scenario checks that a diagram is generated and embedded into the
HTML output, not referenced as an external image.

given file roadmap.subplot
given file roadmap.md
given file b.yaml
given an installed subplot
when I run subplot docgen roadmap.subplot -o roadmap.html
then file roadmap.html matches regex /src="data:image/svg\+xml;base64,/
The sample input file roadmap.md:
This is an example Markdown file, which embeds a roadmap.

~~~roadmap
goal:
  label: |
    This is the end goal:
    if we reach here, there
    is nothing more to be
    done in the project
  depends:
  - finished
  - blocked

finished:
  status: finished
  label: |
    This task is finished;
    the arrow indicates what
    follows this task (unless
    it's blocked)

ready:
  status: ready
  label: |
    This task is ready
    to be done: it is not
    blocked by anything

next:
  status: next
  label: |
    This task is chosen
    to be done next

blocked:
  status: blocked
  label: |
    This task is blocked
    and can't be done until
    something happens
  depends:
  - ready
  - next
~~~
title: Roadmap test
markdowns:
- roadmap.md

Class name validation
When Subplot loads a document it will validate that the block classes
match a known set.  Subplot has a built-in set which it treats as special,
and it knows some custom classes and a number of file type classes.
If the author of a document wishes to use additional class names then they can
include a classes list in the document metadata which subplot will treat
as valid.

given file unknown-class-name.subplot
given file unknown-class-name.md
given file known-class-name.subplot
given file known-class-name.md
given file b.yaml
given an installed subplot
when I try to run subplot docgen unknown-class-name.subplot -o unknown-class-name.html
then command fails
then file unknown-class-name.html does not exist
then stderr contains "Unknown classes found in the document: foobar"
when I run subplot docgen known-class-name.subplot -o known-class-name.html
then file known-class-name.html exists
title: A document with an unknown class name
markdowns:
- unknown-class-name.md
```foobar
This content is foobarish
```
title: A document with a previously unknown class name
markdowns:
- known-class-name.md
classes:
- foobar
```foobar
This content is foobarish
```

Extract embedded files
subplot extract extracts embedded files from a subplot file.

given file embedded-file.subplot
given file embedded-file.md
given file expected.txt
given an installed subplot
when I run subplot extract --merciful embedded-file.subplot foo.txt -d .
then files foo.txt and expected.txt match
title: Embedded file
markdowns:
- embedded-file.md
~~~{#foo.txt .file}
This is a test file.
~~~
This is a test file.

Mistakes in markdown
When there are mistakes in the markdown input, Subplot should report
the location (filename, line, column) where the mistake is, and what
the mistake is. The scenarios in this section verify that.
Scenario before the first heading
Requirement: A scenario must follow a heading.
Justification: the heading can be used as the title for the scenario.

given an installed subplot
given file scenario-before-heading.subplot
given file scenario-before-heading.md
when I try to run subplot docgen scenario-before-heading.subplot -o /dev/null
then command fails
then stderr contains "ERROR: scenario-before-heading.md:1:1: first scenario is before first heading"
title: Foo
markdowns:
  - scenario-before-heading.md
~~~scenario
~~~

Attempt to use definition list
Requirement: Attempt to use definition lists is reported.
Justification: the markdown parser we use in Subplot doesn't support
them, and it would be unhelpful to not tell the user if they try to
use them.

given an installed subplot
given file dl.subplot
given file dl.md
when I try to run subplot docgen dl.subplot -o /dev/null
then command fails
then stderr contains "ERROR: dl.md:3:1: attempt to use definition lists in Markdown"
title: Foo
markdowns:
  - dl.md
# Foo

Some term
: Definition of term.

Bad "add-newline" value
Requirement: Only specific values for the "add-newline" attribute are
allowed for an embedded file.

given an installed subplot
given file add-newline.subplot
given file add-newline.md
when I try to run subplot docgen add-newline.subplot -o /dev/null
then command fails
then stderr contains "ERROR: add-newline.md:1:1: value of add-newline attribute is not understood: xyzzy"
title: Foo
markdowns:
  - add-newline.md
~~~{#foo.txt .file add-newline=xyzzy}
~~~

HTML output
Embedded CSS
Requirement: The user can specify CSS files to embed in the HTML
output.
Justification: We want to allow production of self-standing output
with user-defined styling.

given file embedded-css.subplot
given file embedded-css.md
given file embedded-css.css
given file b.yaml
given an installed subplot
when I run subplot docgen embedded-css.subplot -o foo.html
then file foo.html contains "silly: property;"
title: Embedded CSS
markdowns:
  - embedded-css.md
bindings:
  - b.yaml
css_embed:
 - embedded-css.css
# This is a title

~~~scenario
given precondition
~~~
html {
    silly: property;
}

CSS URLs
Requirement: The user can specify CSS URLs to add in the HTML
output.
Justification: We want to allow users to specify non-embedded CSS.

given file css-urls.subplot
given file css-urls.md
given file b.yaml
given an installed subplot
when I run subplot docgen css-urls.subplot -o foo.html
then file foo.html contains "https://example.com/flushing.css"
title: Embedded CSS
markdowns:
  - css-urls.md
bindings:
  - b.yaml
css_urls:
  - https://example.com/flushing.css
# This is a title

~~~scenario
given precondition
~~~

Running Subplot
The scenarios in this section verify that the Subplot tool can be run
in various specific ways.
Files not in current working directory
Requirement: Subplot can process a subplot that is not in the current
working directory.

given file x/simple.subplot from simple.subplot
given file x/simple.md from simple.md
given file x/b.yaml from b.yaml
given file x/f.py from f.py
given an installed subplot
when I run subplot metadata x/simple.subplot
then command is successful
when I run subplot codegen x/simple.subplot -o test.py
then file test.py exists
when I run subplot docgen x/simple.subplot -o simple.html
then file simple.html exists