Using spawn tag to get errorOutput for warning validation

Explicit step definitions for parallel test verification

Author: eman2673

features/parallel_custom_assign.feature

@@ -1,5 +1,6 @@
 Feature: Running scenarios in parallel with custom assignment
 
+  @spawn
   Scenario: Bad parallel assignment helper uses 1 worker
     Given a file named "features/step_definitions/cucumber_steps.js" with:
       """
@@ -19,11 +20,11 @@ Feature: Running scenarios in parallel with custom assignment
           Then value is 2
       """
     When I run cucumber-js with `--parallel 2`
-    Then it passes
-    And tandem tests verified
+    Then the error output contains the text:
     """
-    expect.fail('No tests should have executed at the same time')
+    WARNING: All workers went idle 2 time(s). Consider revising handler passed to setParallelCanAssign.
     """
+    And no tests ran in tandem
 
   Scenario: Both works run tests when a valid assignment helper is used
     Given a file named "features/step_definitions/cucumber_steps.js" with:
@@ -132,7 +133,4 @@ Feature: Running scenarios in parallel with custom assignment
       """
     When I run cucumber-js with `--parallel 2`
     Then it passes
-    And tandem tests verified
-    """
-    expect(_pickle1.tags[0].name).to.not.eq(_pickle2.tags[0].name)
-    """
+    And tandem tests have unique first tag

features/step_definitions/parallel_steps.ts

@@ -40,6 +40,34 @@ function parse(
   )
 }
 
+function verifyTandem(
+  assertion: (p1: messages.IPickle, p2: messages.IPickle) => void
+) {
+  return function (this: World): void {
+    const running = new Set<string>()
+    const pickles: Dictionary<messages.IPickle> = {}
+    const testCases: Dictionary<string> = {}
+    const testStarts: Dictionary<string> = {}
+
+    const handlers = defaultHandlers({
+      pickles,
+      running,
+      testCases,
+      testStarts,
+    })
+    handlers.testCaseStarted = _.wrap(
+      handlers.testCaseStarted,
+      (fn, t: messages.TestCaseStarted) => {
+        running.forEach((tcId) =>
+          assertion(pickles[testCases[tcId]], pickles[testCases[t.testCaseId]])
+        )
+        fn(t)
+      }
+    )
+    parse(this.lastRun.envelopes, handlers)
+  }
+}
+
 Then(/^it runs tests in order (.+)$/, function (this: World, order: string) {
   const running = new Set<string>()
   const pickles: Dictionary<messages.IPickle> = {}
@@ -52,31 +80,14 @@ Then(/^it runs tests in order (.+)$/, function (this: World, order: string) {
   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')
-      ${assertion}
-    `)
-  }
-
-  const handlers = defaultHandlers({ pickles, running, testCases, testStarts })
-  handlers.testCaseStarted = _.wrap(
-    handlers.testCaseStarted,
-    (fn, t: messages.TestCaseStarted) => {
-      running.forEach((tcId) =>
-        assertFn(pickles[testCases[tcId]], pickles[testCases[t.testCaseId]])
-      )
-      fn(t)
-    }
+Then(
+  /^no tests ran in tandem$/,
+  verifyTandem(() =>
+    expect.fail('No tests should have executed at the same time')
   )
-  parse(this.lastRun.envelopes, handlers)
-})
+)
+
+Then(
+  /^tandem tests have unique first tag$/,
+  verifyTandem((p1, p2) => expect(p1.tags[0].name).to.not.eq(p2.tags[0].name))
+)