fix(coverage): istanbul provider to not break source maps (#9040)

packages/coverage-istanbul/package.json

@@ -45,6 +45,8 @@
   },
   "dependencies": {
     "@istanbuljs/schema": "^0.1.3",
+    "@jridgewell/gen-mapping": "^0.3.13",
+    "@jridgewell/trace-mapping": "catalog:",
     "istanbul-lib-coverage": "catalog:",
     "istanbul-lib-instrument": "^6.0.3",
     "istanbul-lib-report": "catalog:",

packages/coverage-istanbul/src/provider.ts

@@ -5,6 +5,8 @@ import type { CoverageProvider, ReportContext, ResolvedCoverageOptions, Vite, Vi
 import { existsSync, promises as fs } from 'node:fs'
 // @ts-expect-error missing types
 import { defaults as istanbulDefaults } from '@istanbuljs/schema'
+import { addMapping, GenMapping, toEncodedMap } from '@jridgewell/gen-mapping'
+import { eachMapping, TraceMap } from '@jridgewell/trace-mapping'
 import libCoverage from 'istanbul-lib-coverage'
 import { createInstrumenter } from 'istanbul-lib-instrument'
 import libReport from 'istanbul-lib-report'
@@ -85,6 +87,30 @@ export class IstanbulCoverageProvider extends BaseCoverageProvider<ResolvedCover
       id,
       sourceMap as any,
     )
+
+    const transformMap = new GenMapping(sourceMap)
+
+    eachMapping(new TraceMap(sourceMap as any), (mapping) => {
+      addMapping(transformMap, {
+        generated: { line: mapping.generatedLine, column: mapping.generatedColumn },
+        original: { line: mapping.generatedLine, column: mapping.generatedColumn },
+        content: sourceCode,
+        name: mapping.name || '',
+        source: mapping.source || '',
+      })
+    })
+
+    const encodedMap = toEncodedMap(transformMap)
+    delete encodedMap.file
+    delete encodedMap.ignoreList
+    delete encodedMap.sourceRoot
+
+    this.instrumenter.instrumentSync(
+      sourceCode,
+      id,
+      encodedMap as any,
+    )
+
     const map = this.instrumenter.lastSourceMap() as any
     this.transformedModuleIds.add(id)
 

pnpm-lock.yaml

@@ -553,6 +553,12 @@ importers:
       '@istanbuljs/schema':
         specifier: ^0.1.3
         version: 0.1.3
+      '@jridgewell/gen-mapping':
+        specifier: ^0.3.13
+        version: 0.3.13
+      '@jridgewell/trace-mapping':
+        specifier: 'catalog:'
+        version: 0.3.31
       istanbul-lib-coverage:
         specifier: 'catalog:'
         version: 3.2.2
@@ -3097,9 +3103,6 @@ packages:
     resolution: {integrity: sha512-ZXRY4jNvVgSVQ8DL3LTcakaAtXwTVUxE81hslsyD2AtoXW/wVob10HkOJ1X/pAlcI7D+2YoZKg5do8G/w6RYgA==}
     engines: {node: '>=8'}
 
-  '@jridgewell/gen-mapping@0.3.12':
-    resolution: {integrity: sha512-OuLGC46TjB5BbN1dH8JULVVZY4WTdkF7tV9Ys6wLL1rubZnCMstOhNHueU5bLCrnRuDhKPDM4g6sw4Bel5Gzqg==}
-
   '@jridgewell/gen-mapping@0.3.13':
     resolution: {integrity: sha512-2kkt/7niJ6MgEPxF0bYdQ6etZaA+fQvDcLKckhy1yIQOzaoKjBBjSj63/aLVjYE3qhRt5dvM+uUyfCg6UKCBbA==}
 
@@ -9780,7 +9783,7 @@ snapshots:
 
   '@ampproject/remapping@2.3.0':
     dependencies:
-      '@jridgewell/gen-mapping': 0.3.12
+      '@jridgewell/gen-mapping': 0.3.13
       '@jridgewell/trace-mapping': 0.3.31
 
   '@antfu/eslint-config@6.2.0(@vue/compiler-sfc@3.5.25)(eslint@9.39.1(jiti@2.6.1))(typescript@5.9.3)(vitest@packages+vitest)':
@@ -9931,7 +9934,7 @@ snapshots:
     dependencies:
       '@babel/parser': 7.28.5
       '@babel/types': 7.28.4
-      '@jridgewell/gen-mapping': 0.3.12
+      '@jridgewell/gen-mapping': 0.3.13
       '@jridgewell/trace-mapping': 0.3.31
       jsesc: 3.1.0
 
@@ -11278,11 +11281,6 @@ snapshots:
 
   '@istanbuljs/schema@0.1.3': {}
 
-  '@jridgewell/gen-mapping@0.3.12':
-    dependencies:
-      '@jridgewell/sourcemap-codec': 1.5.5
-      '@jridgewell/trace-mapping': 0.3.31
-
   '@jridgewell/gen-mapping@0.3.13':
     dependencies:
       '@jridgewell/sourcemap-codec': 1.5.5

test/coverage-test/fixtures/src/throws-error.ts

@@ -0,0 +1,42 @@
+/**
+ * Some padding
+ */
+export function uncovered() {
+  return "uncoverd";
+}
+
+/**
+ * Some padding
+ */
+
+export function throwsError(condition: Boolean) {
+  /**
+   * Some padding
+   */
+
+  if(condition === false) {
+    /**
+     * Some padding
+     */
+
+    return;
+  }
+
+  /**
+   * Some padding
+   */
+   function throws() {
+     throw new Error("Expected error")
+   }
+  /**
+   * Some padding
+   */
+   throws()
+}
+
+/**
+ * Some padding
+ */
+export function uncovered2() {
+  return "uncoverd";
+}

test/coverage-test/fixtures/test/error-location.test.ts

@@ -0,0 +1,6 @@
+import { test } from "vitest"
+import { throwsError } from "../src/throws-error"
+
+test("throws error", async () => {
+  throwsError(true)
+})

test/coverage-test/test/source-maps.test.ts

@@ -0,0 +1,30 @@
+import { expect } from 'vitest'
+import { isBrowser, runVitest, test } from '../utils'
+
+test('errors point to correct location', async () => {
+  const { stderr } = await runVitest({
+    include: ['fixtures/test/error-location.test.ts'],
+    coverage: { reporter: 'json' },
+  }, { throwOnError: false })
+
+  if (isBrowser()) {
+    expect(stderr).toMatch(`
+❯ throws fixtures/src/throws-error.ts:29:11
+     27|    */
+     28|    function throws() {
+     29|      throw new Error("Expected error")
+       |           ^
+     30|    }
+    `.trim())
+  }
+  else {
+    expect(stderr).toMatch(`
+❯ throws fixtures/src/throws-error.ts:29:12
+     27|    */
+     28|    function throws() {
+     29|      throw new Error("Expected error")
+       |            ^
+     30|    }
+    `.trim())
+  }
+})

test/coverage-test/vitest.config.ts

@@ -87,6 +87,7 @@ export default defineConfig({
             '**/in-source.test.ts',
             '**/query-param-transforms.test.ts',
             '**/test/cjs-dependency.test.ts',
+            '**/test/source-maps.test.ts',
           ],
           exclude: [FIXTURES],
         },
@@ -118,6 +119,7 @@ export default defineConfig({
             '**/in-source.test.ts',
             '**/query-param-transforms.test.ts',
             '**/test/cjs-dependency.test.ts',
+            '**/test/source-maps.test.ts',
           ],
           exclude: [FIXTURES],
         },