feat(coverage): add coverage.changed option to report only changed files

docs/config/coverage.md

@@ -405,3 +405,12 @@ Directory of HTML coverage output to be served in [Vitest UI](/guide/ui) and [HT
 This is automatically configured when using builtin coverage reporters that produce HTML output (`html`, `html-spa`, and `lcov`). Use this option to override with a custom coverage reporting location when using custom coverage reporters.
 
 Note that setting this option does not change where coverage HTML report is generated. Configure the `coverage.reporter` option to change the directory instead.
+
+## coverage.changed
+
+- **Type:** `boolean | string`
+- **Default:** `false` (inherits from `test.changed`)
+- **Available for providers:** `'v8' | 'istanbul'`
+- **CLI:** `--coverage.changed`, `--coverage.changed=<commit/branch>`
+
+Collect coverage only for files changed since a specified commit or branch. When set to `true`, it uses staged and unstaged changes.

docs/guide/cli-generated.md

@@ -278,6 +278,13 @@ High and low watermarks for branches in the format of `<high>,<low>`
 
 High and low watermarks for functions in the format of `<high>,<low>`
 
+### coverage.changed
+
+- **CLI:** `--coverage.changed <commit/branch>`
+- **Config:** [coverage.changed](/config/coverage#coverage-changed)
+
+Collect coverage only for files changed since a specified commit or branch (e.g., `origin/main` or `HEAD~1`). Inherits value from `--changed` by default.
+
 ### mode
 
 - **CLI:** `--mode <name>`

packages/vitest/src/node/cli/cli-config.ts

@@ -306,6 +306,20 @@ export const cliOptionsConfig: VitestCLIOptions = {
           },
         },
       },
+      changed: {
+        description:
+          'Collect coverage only for files changed since a specified commit or branch (e.g., `origin/main` or `HEAD~1`). Inherits value from `--changed` by default.',
+        argument: '<commit/branch>',
+        transform(value) {
+          if (value === 'true' || value === 'yes' || value === true) {
+            return true
+          }
+          if (value === 'false' || value === 'no' || value === false) {
+            return false
+          }
+          return value
+        },
+      },
     },
   },
   mode: {

packages/vitest/src/node/config/resolveConfig.ts

@@ -419,6 +419,9 @@ export function resolveConfig(
   }
 
   resolved.coverage.reporter = resolveCoverageReporters(resolved.coverage.reporter)
+  if (resolved.coverage.changed === undefined && resolved.changed !== undefined) {
+    resolved.coverage.changed = resolved.changed
+  }
 
   if (resolved.coverage.enabled && resolved.coverage.reportsDirectory) {
     const reportsDirectory = resolve(

packages/vitest/src/node/core.ts

@@ -607,6 +607,7 @@ export class Vitest {
       }
 
       await this._testRun.start(specifications).catch(noop)
+      await this.coverageProvider?.onTestRunStart?.()
 
       for (const file of files) {
         await this._reportFileTask(file)
@@ -749,6 +750,7 @@ export class Vitest {
       if (!specifications.length) {
         await this._traces.$('vitest.test_run', async () => {
           await this._testRun.start([])
+          await this.coverageProvider?.onTestRunStart?.()
           const coverage = await this.coverageProvider?.generateCoverage?.({ allTestsRun: true })
 
           await this._testRun.end([], [], coverage)
@@ -880,6 +882,7 @@ export class Vitest {
   private async runFiles(specs: TestSpecification[], allTestsRun: boolean): Promise<TestRunResult> {
     return this._traces.$('vitest.test_run', async () => {
       await this._testRun.start(specs)
+      await this.coverageProvider?.onTestRunStart?.()
 
       // previous run
       await this.cancelPromise

packages/vitest/src/node/coverage.ts

@@ -9,7 +9,7 @@ import { existsSync, promises as fs, readdirSync, writeFileSync } from 'node:fs'
 import module from 'node:module'
 import path from 'node:path'
 import { fileURLToPath } from 'node:url'
-import { slash } from '@vitest/utils/helpers'
+import { cleanUrl, slash } from '@vitest/utils/helpers'
 import { relative, resolve } from 'pathe'
 import pm from 'picomatch'
 import { glob } from 'tinyglobby'
@@ -86,6 +86,7 @@ export class BaseCoverageProvider<Options extends ResolvedCoverageOptions<'istan
   pendingPromises: Promise<void>[] = []
   coverageFilesDirectory!: string
   roots: string[] = []
+  changedFiles?: string[]
 
   _initialize(ctx: Vitest): void {
     this.ctx = ctx
@@ -148,7 +149,7 @@ export class BaseCoverageProvider<Options extends ResolvedCoverageOptions<'istan
   isIncluded(_filename: string, root?: string): boolean {
     const roots = root ? [root] : this.roots
 
-    const filename = slash(_filename)
+    const filename = slash(cleanUrl(_filename))
     const cacheHit = this.globCache.get(filename)
 
     if (cacheHit !== undefined) {
@@ -165,12 +166,16 @@ export class BaseCoverageProvider<Options extends ResolvedCoverageOptions<'istan
     // By default `coverage.include` matches all files, except "coverage.exclude"
     const glob = this.options.include || '**'
 
-    const included = pm.isMatch(filename, glob, {
+    let included = pm.isMatch(filename, glob, {
       contains: true,
       dot: true,
       ignore: this.options.exclude,
     })
 
+    if (included && this.changedFiles) {
+      included = this.changedFiles.includes(filename)
+    }
+
     this.globCache.set(filename, included)
 
     return included
@@ -192,8 +197,8 @@ export class BaseCoverageProvider<Options extends ResolvedCoverageOptions<'istan
     // Run again through picomatch as tinyglobby's exclude pattern is different ({ "exclude": ["math"] } should ignore "src/math.ts")
     includedFiles = includedFiles.filter(file => this.isIncluded(file, root))
 
-    if (this.ctx.config.changed) {
-      includedFiles = (this.ctx.config.related || []).filter(file => includedFiles.includes(file))
+    if (this.changedFiles) {
+      includedFiles = this.changedFiles.filter(file => includedFiles.includes(file))
     }
 
     return includedFiles.map(file => slash(path.resolve(root, file)))
@@ -324,6 +329,23 @@ export class BaseCoverageProvider<Options extends ResolvedCoverageOptions<'istan
     }
   }
 
+  async onTestRunStart(): Promise<void> {
+    if (this.options.changed) {
+      const { VitestGit } = await import('./git')
+      const vitestGit = new VitestGit(this.ctx.config.root)
+      const changedFiles = await vitestGit.findChangedFiles({ changedSince: this.options.changed })
+
+      this.changedFiles = changedFiles ?? undefined
+    }
+    else if (this.ctx.config.changed) {
+      this.changedFiles = this.ctx.config.related
+    }
+
+    if (this.changedFiles) {
+      this.globCache.clear()
+    }
+  }
+
   async onTestFailure(): Promise<void> {
     if (!this.options.reportOnFailure) {
       await this.cleanAfterRun()

packages/vitest/src/node/types/coverage.ts

@@ -28,7 +28,10 @@ export interface CoverageProvider {
   /** Called with coverage results after a single test file has been run */
   onAfterSuiteRun: (meta: AfterSuiteRunMeta) => void | Promise<void>
 
-  /** Callback called when test run fails */
+  /** Callback called when test run starts */
+  onTestRunStart?: () => void | Promise<void>
+
+  /** Callback called when test run fails due to test failures */
   onTestFailure?: () => void | Promise<void>
 
   /** Callback to generate final coverage results */
@@ -274,14 +277,22 @@ export interface BaseCoverageOptions {
    * Use this option to override with custom coverage reporting location.
    */
   htmlDir?: string
+
+  /**
+   * Collect coverage only for files changed since a specified commit or branch.
+   * Inherits the default value from `test.changed`.
+   *
+   * @default false
+   */
+  changed?: boolean | string
 }
 
 export interface CoverageIstanbulOptions extends BaseCoverageOptions {}
 
 export interface CoverageV8Options extends BaseCoverageOptions {}
 
 export interface CustomProviderOptions
-  extends Pick<BaseCoverageOptions, FieldsWithDefaultValues> {
+  extends Pick<BaseCoverageOptions, FieldsWithDefaultValues | 'changed'> {
   /** Name of the module or path to a file to load the custom provider from */
   customProviderModule: string
 }

test/config/test/public.test.ts

@@ -117,3 +117,23 @@ test.for([
     expected && resolve(vitestConfig.root, expected),
   )
 })
+
+test('coverage.changed inherits from test.changed but can be overridden', async () => {
+  const { vitestConfig: inherited } = await resolveConfig({
+    changed: 'HEAD',
+    coverage: {
+      reporter: 'json',
+    },
+  })
+
+  expect(inherited.coverage.changed).toBe('HEAD')
+
+  const { vitestConfig: overridden } = await resolveConfig({
+    changed: 'HEAD',
+    coverage: {
+      changed: false,
+    },
+  })
+
+  expect(overridden.coverage.changed).toBe(false)
+})

test/core/test/cli-test.test.ts

@@ -60,6 +60,7 @@ test('nested coverage options have correct types', async () => {
     --coverage.thresholds.100 25
 
     --coverage.provider v8
+    --coverage.changed HEAD
     --coverage.reporter text
     --coverage.reportsDirectory .\\dist\\coverage
     --coverage.customProviderModule=./folder/coverage.js
@@ -81,6 +82,7 @@ test('nested coverage options have correct types', async () => {
     enabled: true,
     reporter: ['text'],
     provider: 'v8',
+    changed: 'HEAD',
     clean: false,
     cleanOnRerun: true,
     reportsDirectory: 'dist/coverage',

test/coverage-test/test/changed.test.ts

@@ -68,3 +68,99 @@ test('{ changed: "HEAD" }', { skip: SKIP }, async () => {
     }
   `)
 })
+
+test('{ coverage.changed: "HEAD" }', async () => {
+  await runVitest({
+    include: [
+      'fixtures/test/file-to-change.test.ts',
+      'fixtures/test/math.test.ts',
+    ],
+    coverage: {
+      include: [
+        'fixtures/src/file-to-change.ts',
+        'fixtures/src/new-uncovered-file.ts',
+
+        // Should not show up
+        'fixtures/src/untested-file.ts',
+        'fixtures/src/math.ts',
+      ],
+      reporter: 'json',
+      changed: 'HEAD',
+    },
+  })
+
+  const coverageMap = await readCoverageMap()
+
+  expect(coverageMap.files()).toMatchInlineSnapshot(`
+    [
+      "<process-cwd>/fixtures/src/file-to-change.ts",
+      "<process-cwd>/fixtures/src/new-uncovered-file.ts",
+    ]
+  `)
+})
+
+test('{ coverage.changed: "HEAD", excludeAfterRemap: true }', async () => {
+  await runVitest({
+    include: [
+      'fixtures/test/file-to-change.test.ts',
+      'fixtures/test/math.test.ts',
+    ],
+    coverage: {
+      include: [
+        'fixtures/src/file-to-change.ts',
+        'fixtures/src/new-uncovered-file.ts',
+
+        // Should not show up
+        'fixtures/src/untested-file.ts',
+        'fixtures/src/math.ts',
+      ],
+      reporter: 'json',
+      changed: 'HEAD',
+      excludeAfterRemap: true,
+    },
+  })
+
+  const coverageMap = await readCoverageMap()
+
+  expect(coverageMap.files()).toMatchInlineSnapshot(`
+    [
+      "<process-cwd>/fixtures/src/file-to-change.ts",
+      "<process-cwd>/fixtures/src/new-uncovered-file.ts",
+    ]
+  `)
+})
+
+test('{ changed: "v0.0.1", coverage.changed: "HEAD" }', async () => {
+  await runVitest({
+    include: [
+      'fixtures/test/file-to-change.test.ts',
+      'fixtures/test/math.test.ts',
+    ],
+
+    // v0.0.1 is an actual git tag in Vitest repository
+    changed: 'v0.0.1',
+
+    coverage: {
+      include: [
+        'fixtures/src/file-to-change.ts',
+        'fixtures/src/new-uncovered-file.ts',
+
+        // Should not show up
+        'fixtures/src/untested-file.ts',
+        'fixtures/src/math.ts',
+      ],
+      reporter: 'json',
+      changed: 'HEAD',
+    },
+  })
+
+  const coverageMap = await readCoverageMap()
+
+  // Should show changes since HEAD, not v0.0.1
+  expect(coverageMap.files()).toMatchInlineSnapshot(`
+    [
+      "<process-cwd>/fixtures/src/file-to-change.ts",
+      "<process-cwd>/fixtures/src/new-uncovered-file.ts",
+    ]
+  `)
+})

test/coverage-test/test/query-param-transforms.test.ts

@@ -1,4 +1,6 @@
-import { expect } from 'vitest'
+import { readFileSync, writeFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+import { expect, onTestFinished } from 'vitest'
 import { readCoverageMap, runVitest, test } from '../utils'
 
 test('query param based transforms are resolved properly', async () => {
@@ -46,3 +48,53 @@ test('query param based transforms are resolved properly', async () => {
     ]
   `)
 })
+
+test.each([{ changed: 'HEAD' }, { coverage: { changed: 'HEAD' } }])('query param transforms respect %s', async (options) => {
+  const filePath = resolve('./fixtures/src/query-param-transformed.ts')
+  const original = readFileSync(filePath, 'utf8')
+
+  onTestFinished(() => writeFileSync(filePath, original, 'utf8'))
+  writeFileSync(filePath, `${original}\nexport const changedMarker = true\n`, 'utf8')
+
+  await runVitest({
+    config: 'fixtures/configs/vitest.config.query-param-transform.ts',
+    include: ['fixtures/test/query-param.test.ts'],
+    ...options,
+    coverage: { reporter: 'json', ...options.coverage },
+  })
+
+  const coverageMap = await readCoverageMap()
+
+  expect(coverageMap.files()).toMatchInlineSnapshot(`
+    [
+      "<process-cwd>/fixtures/src/query-param-transformed.ts",
+    ]
+  `)
+
+  const coverage = coverageMap.fileCoverageFor(coverageMap.files()[0])
+
+  const functionCoverage = Object.keys(coverage.fnMap)
+    .map(index => ({ name: coverage.fnMap[index].name, hits: coverage.f[index] }))
+    .sort((a, b) => a.name.localeCompare(b.name))
+
+  expect(functionCoverage).toMatchInlineSnapshot(`
+    [
+      {
+        "hits": 1,
+        "name": "first",
+      },
+      {
+        "hits": 3,
+        "name": "initial",
+      },
+      {
+        "hits": 1,
+        "name": "second",
+      },
+      {
+        "hits": 0,
+        "name": "uncovered",
+      },
+    ]
+  `)
+})