test: add failing test for #3251

test/workspaces/coverage-report-tests/check-coverage.test.ts

@@ -19,3 +19,25 @@ test('file coverage summary matches', () => {
   expect(branches.total - branches.covered).toBe(1)
   expect(functions.total - functions.covered).toBe(1)
 })
+
+test('multi environment coverage is merged correctly', async () => {
+  const coverageJson = JSON.parse(readFileSync('./coverage/coverage-final.json', 'utf-8'))
+  const coverageMap = libCoverage.createCoverageMap(coverageJson)
+  const fileCoverage = coverageMap.fileCoverageFor(resolve('./space-multi-transform/src/multi-transform.ts'))
+  const lineCoverage = fileCoverage.getLineCoverage()
+
+  // Condition not covered by any test
+  expect(lineCoverage[13]).toBe(0)
+
+  // Condition covered by Project #1 but not by Project #2
+  expect(lineCoverage[18]).toBe(1)
+
+  // Condition not covered by any test
+  expect(lineCoverage[22]).toBe(0)
+
+  // Condition covered by Project #1 but not by Project #2
+  expect(lineCoverage[26]).toBe(1)
+
+  // Condition covered by both tests
+  expect(lineCoverage[30]).toBe(2)
+})

test/workspaces/package.json

@@ -8,6 +8,7 @@
     "test:coverage": "vitest run --root coverage-report-tests"
   },
   "devDependencies": {
+    "@ampproject/remapping": "^2.2.1",
     "@types/istanbul-lib-coverage": "^2.0.4",
     "istanbul-lib-coverage": "^3.2.0",
     "jsdom": "latest",

test/workspaces/space-multi-transform/src/multi-transform.ts

@@ -0,0 +1,31 @@
+/**
+ * The variable below is modified by custom Vite plugin
+ */
+export const padding = 'default-padding'
+
+export function run(name: string) {
+  /*
+   * These if-branches should show correctly on coverage report.
+   * Otherwise source maps are off.
+   */
+  if (name === 'not-covered') {
+    // This is not covered by any test
+    return 0
+  }
+  // Comment
+  else if (name === 'project-1') {
+    // This is covered by Project #1
+    return 1
+  }
+  else if (name === 'not-covered-2') {
+    // This is not covered by any test
+    return 0
+  }
+  else if (name === 'project-2') {
+    // This is covered by Project #2
+    return 2
+  }
+
+  // This is covered by both projects, should show 2x hits
+  return 3
+}

test/workspaces/space-multi-transform/test/project-1.test.ts

@@ -0,0 +1,9 @@
+import { expect, test } from 'vitest'
+
+import { run } from '../src/multi-transform'
+
+test('cover some branches', () => {
+  expect(run('project-1')).toBe(1)
+
+  expect(run('last branch')).toBe(3)
+})

test/workspaces/space-multi-transform/test/project-2.test.ts

@@ -0,0 +1,9 @@
+import { expect, test } from 'vitest'
+
+import { run } from '../src/multi-transform'
+
+test('cover some branches', () => {
+  expect(run('project-2')).toBe(2)
+
+  expect(run('last branch')).toBe(3)
+})

test/workspaces/vitest.workspace.ts

@@ -1,4 +1,7 @@
 import { defineWorkspace } from 'vitest/config'
+import MagicString from 'magic-string'
+import remapping from '@ampproject/remapping'
+import type { Plugin } from 'vite'
 
 export default defineWorkspace([
   './space_2/*',
@@ -19,4 +22,45 @@ export default defineWorkspace([
       setupFiles: ['./setup.node.ts'],
     },
   },
+
+  // These two projects run on same environment but still transform
+  // a single file differently due to Vite plugins
+  {
+    plugins: [customPlugin(0)],
+    test: {
+      name: 'Project with custom plugin #1',
+      environment: 'node',
+      include: ['./space-multi-transform/test/project-1.test.ts'],
+    },
+  },
+  {
+    plugins: [customPlugin(15)],
+    test: {
+      name: 'Project with custom plugin #2',
+      environment: 'node',
+      include: ['./space-multi-transform/test/project-2.test.ts'],
+    },
+  },
 ])
+
+function customPlugin(offset: number): Plugin {
+  return {
+    name: 'vitest-custom-multi-transform',
+    enforce: 'pre',
+    transform(code, id) {
+      if (id.includes('space-multi-transform/src/multi-transform.ts')) {
+        const padding = '\n*****'.repeat(offset)
+
+        const transformed = new MagicString(code)
+        transformed.replace('\'default-padding\'', `\`${padding}\``)
+
+        const map = remapping(
+          [transformed.generateMap({ hires: true }), this.getCombinedSourcemap() as any],
+          () => null,
+        ) as any
+
+        return { code: transformed.toString(), map }
+      }
+    },
+  }
+}