[test visibility] Fix num tests reported by EFD (#4783)

packages/dd-trace/src/ci-visibility/early-flake-detection/get-known-tests.js

@@ -12,19 +12,7 @@ const {
   TELEMETRY_KNOWN_TESTS_RESPONSE_BYTES
 } = require('../../ci-visibility/telemetry')
 
-function getNumTests (knownTests) {
-  let totalNumTests = 0
-
-  for (const testModule of Object.values(knownTests)) {
-    for (const testSuite of Object.values(testModule)) {
-      for (const testList of Object.values(testSuite)) {
-        totalNumTests += testList.length
-      }
-    }
-  }
-
-  return totalNumTests
-}
+const { getNumFromKnownTests } = require('../../plugins/util/test')
 
 function getKnownTests ({
   url,
@@ -102,7 +90,7 @@ function getKnownTests ({
       try {
         const { data: { attributes: { tests: knownTests } } } = JSON.parse(res)
 
-        const numTests = getNumTests(knownTests)
+        const numTests = getNumFromKnownTests(knownTests)
 
         incrementCountMetric(TELEMETRY_KNOWN_TESTS_RESPONSE_TESTS, {}, numTests)
         distributionMetric(TELEMETRY_KNOWN_TESTS_RESPONSE_BYTES, {}, res.length)

packages/dd-trace/src/plugins/util/test.js

@@ -180,7 +180,8 @@ module.exports = {
   TEST_BROWSER_NAME,
   TEST_BROWSER_VERSION,
   getTestSessionName,
-  TEST_LEVEL_EVENT_TYPES
+  TEST_LEVEL_EVENT_TYPES,
+  getNumFromKnownTests
 }
 
 // Returns pkg manager and its version, separated by '-', e.g. npm-8.15.0 or yarn-1.22.19
@@ -618,3 +619,21 @@ function getTestSessionName (config, testCommand, envTags) {
   }
   return testCommand
 }
+
+// Calculate the number of a tests from the known tests response, which has a shape like:
+// { testModule1: { testSuite1: [test1, test2, test3] }, testModule2: { testSuite2: [test4, test5] } }
+function getNumFromKnownTests (knownTests) {
+  if (!knownTests) {
+    return 0
+  }
+
+  let totalNumTests = 0
+
+  for (const testModule of Object.values(knownTests)) {
+    for (const testSuite of Object.values(testModule)) {
+      totalNumTests += testSuite.length
+    }
+  }
+
+  return totalNumTests
+}

packages/dd-trace/test/plugins/util/test.spec.js

@@ -15,7 +15,8 @@ const {
   resetCoverage,
   removeInvalidMetadata,
   parseAnnotations,
-  getIsFaultyEarlyFlakeDetection
+  getIsFaultyEarlyFlakeDetection,
+  getNumFromKnownTests
 } = require('../../../src/plugins/util/test')
 
 const { GIT_REPOSITORY_URL, GIT_COMMIT_SHA, CI_PIPELINE_URL } = require('../../../src/plugins/util/tags')
@@ -335,3 +336,32 @@ describe('getIsFaultyEarlyFlakeDetection', () => {
     expect(isFaulty).to.be.true
   })
 })
+
+describe('getNumFromKnownTests', () => {
+  it('calculates the number of tests from the known tests', () => {
+    const knownTests = {
+      testModule: {
+        'test1.spec.js': ['test1', 'test2'],
+        'test2.spec.js': ['test3']
+      }
+    }
+
+    const numTests = getNumFromKnownTests(knownTests)
+    expect(numTests).to.equal(3)
+  })
+
+  it('does not crash with empty dictionaries', () => {
+    const knownTests = {}
+
+    const numTests = getNumFromKnownTests(knownTests)
+    expect(numTests).to.equal(0)
+  })
+
+  it('does not crash if known tests is undefined or null', () => {
+    const numTestsUndefined = getNumFromKnownTests(undefined)
+    expect(numTestsUndefined).to.equal(0)
+
+    const numTestsNull = getNumFromKnownTests(null)
+    expect(numTestsNull).to.equal(0)
+  })
+})