Parsing test cases to verify order and parallelism

Author: eman2673

features/parallel_custom_assign.feature

@@ -4,11 +4,8 @@ Feature: Running scenarios in parallel with custom assignment
     Given a file named "features/step_definitions/cucumber_steps.js" with:
       """
       const {Then, setParallelCanAssign} = require('@cucumber/cucumber')
-      const {expect} = require('chai')
-      let value = 0;
       setParallelCanAssign(() => false)
       Then(/^value is (\d+)$/, function(v, cb) {
-        expect(++value).to.eq(v)
          setTimeout(cb, 150)
       })
       """
@@ -23,6 +20,10 @@ Feature: Running scenarios in parallel with custom assignment
       """
     When I run cucumber-js with `--parallel 2`
     Then it passes
+    And tandem tests verified
+    """
+    expect.fail('No tests should have executed at the same time')
+    """
 
   Scenario: Both works run tests when a valid assignment helper is used
     Given a file named "features/step_definitions/cucumber_steps.js" with:
@@ -33,7 +34,7 @@ Feature: Running scenarios in parallel with custom assignment
       setParallelCanAssign(() => true)
       Then(/^value is (\d+)$/, function(v, cb) {
         expect(++value).to.eq(v)
-         setTimeout(cb, 150)
+         setTimeout(cb, 300)
       })
       """
     And a file named "features/a.feature" with:
@@ -53,12 +54,9 @@ Feature: Running scenarios in parallel with custom assignment
       """
       const {Given, setParallelCanAssign} = require('@cucumber/cucumber')
       let flag = true
-      let processed = 0;
       setParallelCanAssign(() => (flag = !flag))
       Given(/^scenario (\d+)$/, function(scenario, cb) {
         setTimeout(cb, 150)
-        if (scenario === 1) throw Error(`#${scenario} was test ${++processed} on this worker`)
-        processed++;
       })
       """
     And a file named "features/a.feature" with:
@@ -74,11 +72,8 @@ Feature: Running scenarios in parallel with custom assignment
           Given scenario 3
       """
     When I run cucumber-js with `--parallel 2`
-    Then it fails
-    And the output contains the text:
-    """
-      #1 was test 2 on this worker
-    """
+    Then it passes
+    And it runs tests in order b, c, a
 
   Scenario: assignment is appropriately applied and fails at last processed scenario 'a'
     Given a file named "features/step_definitions/cucumber_steps.js" with:
@@ -136,4 +131,8 @@ Feature: Running scenarios in parallel with custom assignment
           Given scenario simple 3
       """
     When I run cucumber-js with `--parallel 2`
-    Then it passes
+    Then it passes
+    And tandem tests verified
+    """
+    expect(_pickle1.tags[0].name).to.not.eq(_pickle2.tags[0].name)
+    """

features/step_definitions/parallel_steps.ts

@@ -0,0 +1,82 @@
+import { Then } from '../../'
+import { World } from '../support/world'
+import _, { Dictionary } from 'lodash'
+import { messages } from '@cucumber/messages'
+import { expect } from 'chai'
+
+interface TestCaseParser {
+  pickles: Dictionary<messages.IPickle>
+  testCases: Dictionary<string>
+  running: Set<string>
+  testStarts: Dictionary<string>
+}
+
+function defaultHandlers({
+  pickles,
+  testCases,
+  running,
+  testStarts,
+}: TestCaseParser): Record<string, Function> {
+  return {
+    pickle: (p: messages.IPickle) => (pickles[p.id] = p),
+    testCase: (t: messages.TestCase) => (testCases[t.id] = t.pickleId),
+    testCaseStarted: (t: messages.TestCaseStarted) => {
+      running.add(t.testCaseId)
+      testStarts[t.id] = t.testCaseId
+    },
+    testCaseFinished: (t: messages.TestCaseFinished) =>
+      running.delete(testStarts[t.testCaseStartedId]),
+  }
+}
+
+function parse(
+  envelopes: messages.IEnvelope[],
+  handlers: Record<string, Function>
+): void {
+  _.each(envelopes, (envelope) =>
+    _.forOwn(envelope, (value, key) => {
+      ;(handlers[key] || _.noop)(value)
+    })
+  )
+}
+
+Then(/^it runs tests in order (.+)$/, function (this: World, order: string) {
+  const running = new Set<string>()
+  const pickles: Dictionary<messages.IPickle> = {}
+  const testCases: Dictionary<string> = {}
+  const testStarts: Dictionary<string> = {}
+  const scenarioNames = order.split(/,\s*/)
+  const handlers = defaultHandlers({ pickles, running, testCases, testStarts })
+  handlers.testCaseStarted = (t: messages.TestCaseStarted) =>
+    expect(pickles[testCases[t.testCaseId]].name).to.eq(scenarioNames.shift())
+  parse(this.lastRun.envelopes, handlers)
+})
+
+Then(/^tandem tests verified$/, function (this: World, assertion: string) {
+  const running = new Set<string>()
+  const pickles: Dictionary<messages.IPickle> = {}
+  const testCases: Dictionary<string> = {}
+  const testStarts: Dictionary<string> = {}
+  const assertFn = (
+    _pickle1: messages.IPickle,
+    _pickle2: messages.IPickle
+  ): boolean => {
+    // eslint-disable-next-line no-eval
+    return eval(`
+      const { expect } = require('chai')
+      ${assertion}
+    `)
+  }
+
+  const handlers = defaultHandlers({ pickles, running, testCases, testStarts })
+  handlers.testCaseStarted = _.wrap(
+    handlers.testCaseStarted,
+    (fn, t: messages.TestCaseStarted) => {
+      running.forEach((tcId) =>
+        assertFn(pickles[testCases[tcId]], pickles[testCases[t.testCaseId]])
+      )
+      fn(t)
+    }
+  )
+  parse(this.lastRun.envelopes, handlers)
+})