feat(coverage): v8 to ignore empty lines, comments, types (#5457)

docs/config/index.md

@@ -1103,6 +1103,20 @@ List of files included in coverage as glob patterns
 
 List of files excluded from coverage as glob patterns.
 
+This option overrides all default options. Extend the default options when adding new patterns to ignore:
+
+```ts
+import { coverageConfigDefaults, defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    coverage: {
+      exclude: ['**/custom-pattern/**', ...coverageConfigDefaults.exclude]
+    },
+  },
+})
+```
+
 #### coverage.all
 
 - **Type:** `boolean`
@@ -1320,6 +1334,38 @@ Sets thresholds for files matching the glob pattern.
 }
 ```
 
+#### coverage.ignoreEmptyLines
+
+- **Type:** `boolean`
+- **Default:** `false`
+- **Available for providers:** `'v8'`
+- **CLI:** `--coverage.ignoreEmptyLines=<boolean>`
+
+Ignore empty lines, comments and other non-runtime code, e.g. Typescript types.
+
+This option works only if the used compiler removes comments and other non-runtime code from the transpiled code.
+By default Vite uses ESBuild which removes comments and Typescript types from `.ts`, `.tsx` and `.jsx` files.
+
+If you want to apply ESBuild to other files as well, define them in [`esbuild` options](https://vitejs.dev/config/shared-options.html#esbuild):
+
+```ts
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  esbuild: {
+    // Transpile all files with ESBuild to remove comments from code coverage.
+    // Required for `test.coverage.ignoreEmptyLines` to work:
+    include: ['**/*.js', '**/*.jsx', '**/*.mjs', '**/*.ts', '**/*.tsx'],
+  },
+  test: {
+    coverage: {
+      provider: 'v8',
+      ignoreEmptyLines: true,
+    },
+  },
+})
+```
+
 #### coverage.ignoreClassMethods
 
 - **Type:** `string[]`

docs/guide/coverage.md

@@ -43,6 +43,11 @@ npm i -D @vitest/coverage-istanbul
 
 ## Coverage Setup
 
+:::tip
+It's recommended to always define [`coverage.include`](https://vitest.dev/config/#coverage-include) in your configuration file.
+This helps Vitest to reduce the amount of files picked by [`coverage.all`](https://vitest.dev/config/#coverage-all).
+:::
+
 To test with coverage enabled, you can pass the `--coverage` flag in CLI.
 By default, reporter `['text', 'html', 'clover', 'json']` will be used.
 

package.json

@@ -84,7 +84,8 @@
       "@types/[email protected]": "patches/@[email protected]",
       "@sinonjs/[email protected]": "patches/@[email protected]",
       "[email protected]": "patches/[email protected]",
-      "@types/[email protected]": "patches/@[email protected]"
+      "@types/[email protected]": "patches/@[email protected]",
+      "[email protected]": "patches/[email protected]"
     }
   },
   "simple-git-hooks": {

packages/coverage-v8/package.json

@@ -56,8 +56,7 @@
     "picocolors": "^1.0.0",
     "std-env": "^3.5.0",
     "strip-literal": "^2.0.0",
-    "test-exclude": "^6.0.0",
-    "v8-to-istanbul": "^9.2.0"
+    "test-exclude": "^6.0.0"
   },
   "devDependencies": {
     "@types/debug": "^4.1.12",
@@ -66,6 +65,7 @@
     "@types/istanbul-lib-source-maps": "^4.0.4",
     "@types/istanbul-reports": "^3.0.4",
     "pathe": "^1.1.1",
+    "v8-to-istanbul": "^9.2.0",
     "vite-node": "workspace:*",
     "vitest": "workspace:*"
   }

packages/coverage-v8/src/provider.ts

@@ -266,14 +266,12 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
       }
 
       const coverages = await Promise.all(chunk.map(async (filename) => {
-        const transformResult = await this.ctx.vitenode.transformRequest(filename.pathname).catch(() => {})
+        const { originalSource, source } = await this.getSources(filename.href, transformResults)
 
         // Ignore empty files, e.g. files that contain only typescript types and no runtime code
-        if (transformResult && stripLiteral(transformResult.code).trim() === '')
+        if (source && stripLiteral(source).trim() === '')
           return null
 
-        const { originalSource } = await this.getSources(filename.href, transformResults)
-
         const coverage = {
           url: filename.href,
           scriptId: '0',
@@ -309,9 +307,9 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
   }> {
     const filePath = normalize(fileURLToPath(url))
 
-    const transformResult = transformResults.get(filePath)
+    const transformResult = transformResults.get(filePath) || await this.ctx.vitenode.transformRequest(filePath).catch(() => {})
 
-    const map = transformResult?.map
+    const map = transformResult?.map as (EncodedSourceMap | undefined)
     const code = transformResult?.code
     const sourcesContent = map?.sourcesContent?.[0] || await fs.readFile(filePath, 'utf-8').catch(() => {
       // If file does not exist construct a dummy source for it.
@@ -367,7 +365,7 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
         // If no source map was found from vite-node we can assume this file was not run in the wrapper
         const wrapperLength = sources.sourceMap ? WRAPPER_LENGTH : 0
 
-        const converter = v8ToIstanbul(url, wrapperLength, sources)
+        const converter = v8ToIstanbul(url, wrapperLength, sources, undefined, this.options.ignoreEmptyLines)
         await converter.load()
 
         converter.applyCoverage(functions)

packages/vitest/src/defaults.ts

@@ -43,6 +43,7 @@ export const coverageConfigDefaults: ResolvedCoverageOptions = {
   reporter: [['text', {}], ['html', {}], ['clover', {}], ['json', {}]],
   extension: ['.js', '.cjs', '.mjs', '.ts', '.mts', '.cts', '.tsx', '.jsx', '.vue', '.svelte', '.marko'],
   allowExternal: false,
+  ignoreEmptyLines: false,
   processingConcurrency: Math.min(20, os.availableParallelism?.() ?? os.cpus().length),
 }
 

packages/vitest/src/types/coverage.ts

@@ -233,7 +233,12 @@ export interface CoverageIstanbulOptions extends BaseCoverageOptions {
   ignoreClassMethods?: string[]
 }
 
-export interface CoverageV8Options extends BaseCoverageOptions {}
+export interface CoverageV8Options extends BaseCoverageOptions {
+  /**
+   * Ignore empty lines, comments and other non-runtime code, e.g. Typescript types
+   */
+  ignoreEmptyLines?: boolean
+}
 
 export interface CustomProviderOptions extends Pick<BaseCoverageOptions, FieldsWithDefaultValues> {
   /** Name of the module or path to a file to load the custom provider from */

patches/v8-to-istanbul@9.2.0.patch

@@ -0,0 +1,156 @@
+diff --git a/CHANGELOG.md b/CHANGELOG.md
+deleted file mode 100644
+index 4f7e3bc8d1bba4feb51044ff9eb77b41f972f957..0000000000000000000000000000000000000000
+diff --git a/index.d.ts b/index.d.ts
+index ee7b286844f2bf96357218166e26e1c338f774cf..657531b7c75f43e9a4e957dd1f10797e44da5bb1 100644
+--- a/index.d.ts
++++ b/index.d.ts
+@@ -1,5 +1,7 @@
+ /// <reference types="node" />
+
++// Patch applied: https://github.com/istanbuljs/v8-to-istanbul/pull/244
++
+ import { Profiler } from 'inspector'
+ import { CoverageMapData } from 'istanbul-lib-coverage'
+ import { SourceMapInput } from '@jridgewell/trace-mapping'
+@@ -20,6 +22,6 @@ declare class V8ToIstanbul {
+   toIstanbul(): CoverageMapData
+ }
+
+-declare function v8ToIstanbul(scriptPath: string, wrapperLength?: number, sources?: Sources, excludePath?: (path: string) => boolean): V8ToIstanbul
++declare function v8ToIstanbul(scriptPath: string, wrapperLength?: number, sources?: Sources, excludePath?: (path: string) => boolean, excludeEmptyLines?: boolean): V8ToIstanbul
+
+ export = v8ToIstanbul
+diff --git a/index.js b/index.js
+index 4db27a7d84324d0e6605c5506e3eee5665ddfeb0..7bfb839634b1e3c54efedc3c270d82edc4167a64 100644
+--- a/index.js
++++ b/index.js
+@@ -1,5 +1,6 @@
++// Patch applied: https://github.com/istanbuljs/v8-to-istanbul/pull/244
+ const V8ToIstanbul = require('./lib/v8-to-istanbul')
+
+-module.exports = function (path, wrapperLength, sources, excludePath) {
+-  return new V8ToIstanbul(path, wrapperLength, sources, excludePath)
++module.exports = function (path, wrapperLength, sources, excludePath, excludeEmptyLines) {
++  return new V8ToIstanbul(path, wrapperLength, sources, excludePath, excludeEmptyLines)
+ }
+diff --git a/lib/source.js b/lib/source.js
+index d8ebc215f6ad83d472abafe976935acfe5c61b04..021fd2aed1f73ebb4adc449ce6e96f2d89c295a5 100644
+--- a/lib/source.js
++++ b/lib/source.js
+@@ -1,23 +1,32 @@
++// Patch applied: https://github.com/istanbuljs/v8-to-istanbul/pull/244
+ const CovLine = require('./line')
+ const { sliceRange } = require('./range')
+-const { originalPositionFor, generatedPositionFor, GREATEST_LOWER_BOUND, LEAST_UPPER_BOUND } = require('@jridgewell/trace-mapping')
++const { originalPositionFor, generatedPositionFor, eachMapping, GREATEST_LOWER_BOUND, LEAST_UPPER_BOUND } = require('@jridgewell/trace-mapping')
+
+ module.exports = class CovSource {
+-  constructor (sourceRaw, wrapperLength) {
++  constructor (sourceRaw, wrapperLength, traceMap) {
+     sourceRaw = sourceRaw ? sourceRaw.trimEnd() : ''
+     this.lines = []
+     this.eof = sourceRaw.length
+     this.shebangLength = getShebangLength(sourceRaw)
+     this.wrapperLength = wrapperLength - this.shebangLength
+-    this._buildLines(sourceRaw)
++    this._buildLines(sourceRaw, traceMap)
+   }
+
+-  _buildLines (source) {
++  _buildLines (source, traceMap) {
+     let position = 0
+     let ignoreCount = 0
+     let ignoreAll = false
++    const linesToCover = traceMap && this._parseLinesToCover(traceMap)
++
+     for (const [i, lineStr] of source.split(/(?<=\r?\n)/u).entries()) {
+-      const line = new CovLine(i + 1, position, lineStr)
++      const lineNumber = i + 1
++      const line = new CovLine(lineNumber, position, lineStr)
++
++      if (linesToCover && !linesToCover.has(lineNumber)) {
++        line.ignore = true
++      }
++
+       if (ignoreCount > 0) {
+         line.ignore = true
+         ignoreCount--
+@@ -125,6 +134,18 @@ module.exports = class CovSource {
+     if (this.lines[line - 1] === undefined) return this.eof
+     return Math.min(this.lines[line - 1].startCol + relCol, this.lines[line - 1].endCol)
+   }
++
++  _parseLinesToCover (traceMap) {
++    const linesToCover = new Set()
++
++    eachMapping(traceMap, (mapping) => {
++      if (mapping.originalLine !== null) {
++        linesToCover.add(mapping.originalLine)
++      }
++    })
++
++    return linesToCover
++  }
+ }
+
+ // this implementation is pulled over from istanbul-lib-sourcemap:
+diff --git a/lib/v8-to-istanbul.js b/lib/v8-to-istanbul.js
+index 3616437b00658861dc5a8910c64d1449e9fdf467..c1e0c0ae19984480e408713d1691fa174a7c4c1f 100644
+--- a/lib/v8-to-istanbul.js
++++ b/lib/v8-to-istanbul.js
+@@ -1,3 +1,4 @@
++// Patch applied: https://github.com/istanbuljs/v8-to-istanbul/pull/244
+ const assert = require('assert')
+ const convertSourceMap = require('convert-source-map')
+ const util = require('util')
+@@ -25,12 +26,13 @@ const isNode8 = /^v8\./.test(process.version)
+ const cjsWrapperLength = isOlderNode10 ? require('module').wrapper[0].length : 0
+
+ module.exports = class V8ToIstanbul {
+-  constructor (scriptPath, wrapperLength, sources, excludePath) {
++  constructor (scriptPath, wrapperLength, sources, excludePath, excludeEmptyLines) {
+     assert(typeof scriptPath === 'string', 'scriptPath must be a string')
+     assert(!isNode8, 'This module does not support node 8 or lower, please upgrade to node 10')
+     this.path = parsePath(scriptPath)
+     this.wrapperLength = wrapperLength === undefined ? cjsWrapperLength : wrapperLength
+     this.excludePath = excludePath || (() => false)
++    this.excludeEmptyLines = excludeEmptyLines === true
+     this.sources = sources || {}
+     this.generatedLines = []
+     this.branches = {}
+@@ -58,8 +60,8 @@ module.exports = class V8ToIstanbul {
+         if (!this.sourceMap.sourcesContent) {
+           this.sourceMap.sourcesContent = await this.sourcesContentFromSources()
+         }
+-        this.covSources = this.sourceMap.sourcesContent.map((rawSource, i) => ({ source: new CovSource(rawSource, this.wrapperLength), path: this.sourceMap.sources[i] }))
+-        this.sourceTranspiled = new CovSource(rawSource, this.wrapperLength)
++        this.covSources = this.sourceMap.sourcesContent.map((rawSource, i) => ({ source: new CovSource(rawSource, this.wrapperLength, this.excludeEmptyLines ? this.sourceMap : null), path: this.sourceMap.sources[i] }))
++        this.sourceTranspiled = new CovSource(rawSource, this.wrapperLength, this.excludeEmptyLines ? this.sourceMap : null)
+       } else {
+         const candidatePath = this.rawSourceMap.sourcemap.sources.length >= 1 ? this.rawSourceMap.sourcemap.sources[0] : this.rawSourceMap.sourcemap.file
+         this.path = this._resolveSource(this.rawSourceMap, candidatePath || this.path)
+@@ -82,8 +84,8 @@ module.exports = class V8ToIstanbul {
+           // We fallback to reading the original source from disk.
+           originalRawSource = await readFile(this.path, 'utf8')
+         }
+-        this.covSources = [{ source: new CovSource(originalRawSource, this.wrapperLength), path: this.path }]
+-        this.sourceTranspiled = new CovSource(rawSource, this.wrapperLength)
++        this.covSources = [{ source: new CovSource(originalRawSource, this.wrapperLength, this.excludeEmptyLines ? this.sourceMap : null), path: this.path }]
++        this.sourceTranspiled = new CovSource(rawSource, this.wrapperLength, this.excludeEmptyLines ? this.sourceMap : null)
+       }
+     } else {
+       this.covSources = [{ source: new CovSource(rawSource, this.wrapperLength), path: this.path }]
+@@ -281,8 +283,10 @@ module.exports = class V8ToIstanbul {
+       s: {}
+     }
+     source.lines.forEach((line, index) => {
+-      statements.statementMap[`${index}`] = line.toIstanbul()
+-      statements.s[`${index}`] = line.ignore ? 1 : line.count
++      if (!line.ignore) {
++        statements.statementMap[`${index}`] = line.toIstanbul()
++        statements.s[`${index}`] = line.count
++      }
+     })
+     return statements
+   }