test: workspace coverage with multiple transforms

packages/coverage-c8/src/provider.ts

@@ -100,8 +100,13 @@ export class C8CoverageProvider extends BaseCoverageProvider implements Coverage
     const sourceMapMeta: Record<SourceMapMeta['url'], MapAndSource> = {}
     const extensions = Array.isArray(this.options.extension) ? this.options.extension : [this.options.extension]
 
+    // TODO: Fixed in #3226
+    const fetchCache = this.ctx.projects.map(project =>
+      Array.from(project.vitenode.fetchCache.entries()),
+    ).flat()
+
     const entries = Array
-      .from(this.ctx.vitenode.fetchCache.entries())
+      .from(fetchCache)
       .filter(entry => report._shouldInstrument(entry[0]))
       .map(([file, { result }]) => {
         if (!result.map)

test/workspaces/space_1/test/multiple-transforms.spec.ts

@@ -0,0 +1,6 @@
+import { expect, test } from 'vitest'
+import run from '../../src/multiple-transforms'
+
+test('cover space 1 related transforms', () => {
+  expect(run()).toBe('OK')
+})

test/workspaces/space_1/vite.config.ts

@@ -1,6 +1,28 @@
 import { defineProject } from 'vitest/config'
+import MagicString from 'magic-string'
 
 export default defineProject({
+  plugins: [
+    {
+      name: 'custom:workspace-1',
+      transform(code, id) {
+        if (id.endsWith('multiple-transforms.ts')) {
+          const s = new MagicString(code)
+          const start = code.indexOf('//! WORKSPACE_1_REMOVE_START')
+          const end = code.indexOf('//! WORKSPACE_1_REMOVE_END')
+
+          s.remove(start, end + '//! WORKSPACE_1_REMOVE_END'.length)
+          return {
+            code: s.toString(),
+            map: s.generateMap({
+              hires: true,
+              source: id,
+            }),
+          }
+        }
+      },
+    },
+  ],
   test: {
     name: 'space_1',
     environment: 'happy-dom',

test/workspaces/space_3/multiple-transforms.space-3-test.ts

@@ -0,0 +1,6 @@
+import { expect, test } from 'vitest'
+import run from '../src/multiple-transforms'
+
+test('cover space 3 related transforms', () => {
+  expect(run()).toBe('OK')
+})

test/workspaces/space_3/vitest.config.ts

@@ -1,6 +1,28 @@
+import MagicString from 'magic-string'
 import { defineProject } from 'vitest/config'
 
 export default defineProject({
+  plugins: [
+    {
+      name: 'custom:workspace-3',
+      transform(code, id) {
+        if (id.endsWith('multiple-transforms.ts')) {
+          const s = new MagicString(code)
+          const start = code.indexOf('//! WORKSPACE_3_REMOVE_START')
+          const end = code.indexOf('//! WORKSPACE_3_REMOVE_END')
+
+          s.remove(start, end + '//! WORKSPACE_3_REMOVE_END'.length)
+          return {
+            code: s.toString(),
+            map: s.generateMap({
+              hires: true,
+              source: id,
+            }),
+          }
+        }
+      },
+    },
+  ],
   test: {
     include: ['**/*.space-3-test.ts'],
     name: 'space_3',

test/workspaces/src/multiple-transforms.ts

@@ -0,0 +1,54 @@
+/* eslint-disable spaced-comment, unused-imports/no-unused-vars */
+
+export default function run(a = 1, b = 2) {
+  //! WORKSPACE_1_REMOVE_START
+
+  // In workspace 1 we remove two functions
+  function removedFunctionOne() {
+    return 1
+  }
+  function removedFunctionThree() {
+    return 1
+  }
+
+  //! WORKSPACE_1_REMOVE_END
+
+  const unusedFunction1 = () => 1
+  const unusedFunction2 = () => a ? b : null
+
+  // Coverage of this branch breaks when combined coverage of workspaces is not handled correctly
+  if (a === 1000 && b === 1) {
+    // This should be uncovered
+    return 1001
+  }
+
+  //! WORKSPACE_3_REMOVE_START
+
+  // In workspace 3 we remove three branches
+  if (a === 100 && b === 1)
+    return 101
+
+  if (a === 100 && b === 2)
+    return 102
+
+  if (a === 100 && b === 3)
+    return 103
+
+  //! WORKSPACE_3_REMOVE_END
+
+  function unusedFunction3() {
+    return 1
+  }
+
+  // Coverage of this branch breaks when combined coverage of workspaces is not handled correctly
+  if (a === 1000 && b === 2) {
+    // This should be uncovered
+    return 1002
+  }
+
+  function unusedFunction4() {
+    return 1
+  }
+
+  return 'OK'
+}