cancel context for each scenario

[draganm]

🤔 What's changed?

Each Scenario gets a cancellable context that is cancelled at the end of the scenario.

⚡️ What's your motivation?

Cancelled context can be used to shut down mock services that are run in the scope of one Scenario (see #513)

🏷️ What kind of change is this?

• ⚡ New feature (non-breaking change which adds new behaviour)

♻️ Anything particular you want feedback on?

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

---

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[draganm]

Not sure how to end-to-end test this though.

[codecov]

Codecov Report

Merging #514 (9c3a47d) into main (aba6a68) will decrease coverage by 0.81%.
The diff coverage is 100.00%.

❗ Current head 9c3a47d differs from pull request most recent head 9ea8682. Consider uploading reports for the commit 9ea8682 to get more accurate results

@@            Coverage Diff             @@
##             main     #514      +/-   ##
==========================================
- Coverage   82.94%   82.13%   -0.81%     
==========================================
  Files          28       27       -1     
  Lines        3371     3320      -51     
==========================================
- Hits         2796     2727      -69     
- Misses        461      484      +23     
+ Partials      114      109       -5     

Impacted Files	Coverage Δ
suite.go	88.88% <100.00%> (-0.38%)	⬇️

... and 4 files with indirect coverage changes

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[mirogta]

This looks great. Would you mind adding a simple example code as well as part of this PR? I would prefer if each use case (like your new one, however it looks cool) has an appropriate example to follow otherwise some less experienced developers might be a bit lost in how to use it.

[vearutop]

I think this is a good idea, although it potentially can break existing scenarios that depend (implicitly or explicitly) on background tasks after the scenario has ended already.
In such (rare?) cases, context cancellation can be canceled 🙃 with help of a simple wrapper.

[vearutop]

Not sure how to end-to-end test this though.

@draganm for example, you can update suite_context_test.go with such test:

func TestScenarioContext_After_cancelled(t *testing.T) {
	ctxDone := make(chan struct{})
	suite := TestSuite{
		ScenarioInitializer: func(scenarioContext *ScenarioContext) {
			scenarioContext.When(`^foo$`, func() { return })
			scenarioContext.After(func(ctx context.Context, sc *Scenario, err error) (context.Context, error) {
				go func() {
					<-ctx.Done()
					close(ctxDone)
				}()

				return ctx, nil
			})
		},
		Options: &Options{
			Format:   "pretty",
			TestingT: t,
			FeatureContents: []Feature{
				{
					Name: "Scenario Context Cancellation",
					Contents: []byte(`
Feature: dummy
  Scenario: Context should be cancelled by the end of scenario
    When foo
`),
				},
			},
		},
	}

	require.Equal(t, 0, suite.Run(), "non-zero status returned, failed to run feature tests")

	select {
	case <-ctxDone:
		return
	case <-time.After(5 * time.Second):
		assert.Fail(t, "failed to wait for context cancellation")
	}
}

[vearutop]

Actually, I think this is good to merge, and I'll add a test in a follow-up commit.

[aslakhellesoy]

Hi @draganm,

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