feat(reporters)!: write json and junit reporter output files to .vitest by default (#10621)

hi-ogawa · OpenCode (claude-opus-4-8) · AriPerkkio · web-flow · commit 58577290ad65 · 2026-06-25T15:51:45.000+09:00
Co-authored-by: Hiroshi Ogawa &lt;4232207+hi-ogawa@users.noreply.github.com&gt;
Co-authored-by: OpenCode (claude-opus-4-8) &lt;noreply@opencode.ai&gt;
Co-authored-by: Ari Perkkiö &lt;ari.perkkio@gmail.com&gt;
diff --git a/docs/guide/migration.md b/docs/guide/migration.md
@@ -181,6 +181,10 @@ Vitest now uses a single `.vitest` directory at the project root as the shared a
 - **Attachments** ([`attachmentsDir`](/config/attachmentsdir)): `.vitest-attachements/` → `.vitest/attachments/`
 - **Blob reporter** and `--merge-reports`: `.vitest-reports/blob-*.json` → `.vitest/blob/blob-*.json`
 - **HTML reporter** ([`html`](/guide/reporters#html-reporter)): `html/index.html` → `.vitest/index.html`, and its option changed from `outputFile` (a file) to `outputDir` (a directory)
+- **JSON reporter** ([`json`](/guide/reporters#json-reporter)): stdout → `.vitest/json/output.json`
+- **JUnit reporter** ([`junit`](/guide/reporters#junit-reporter)): stdout → `.vitest/junit/output.xml`
+
+The `json` and `junit` reporters now write to a file by default instead of printing to stdout. If you previously relied on the report being printed to stdout (for example `vitest --reporter=json > out.json` or `vitest --reporter=json | jq`), either read the generated artifact file instead (for example `jq . .vitest/json/output.json`), or opt back into stdout with the reporter's `stdout` option (`reporters: [['json', { stdout: true }]]`). An explicit `outputFile` is still respected and unchanged.
 
 ### `toMatchScreenshot` Now Uses a Dedicated Screenshot Directory Config
 
diff --git a/docs/guide/reporters.md b/docs/guide/reporters.md
@@ -60,7 +60,13 @@ export default defineConfig({
 
 ## Reporter Output
 
-By default, Vitest's reporters will print their output to the terminal. When using the `json` or `junit` reporters, you can instead write your tests' output to a file by including an `outputFile` [configuration option](/config/outputfile) either in your Vite configuration file or via CLI. The `html` reporter writes a report directory instead; see its [`outputDir`](#html-reporter) option.
+By default, Vitest's reporters print their output to the terminal. The `json`, `junit` and `html` reporters instead write to a scoped location under `.vitest/`:
+
+- `json` writes `.vitest/json/output.json`
+- `junit` writes `.vitest/junit/output.xml`
+- `html` writes `.vitest/index.html`
+
+The `json` and `junit` locations can be overridden with the `outputFile` [configuration option](/config/outputfile) in your Vitest configuration file or via CLI. The `html` reporter uses its [`outputDir`](#html-reporter) option instead.
 
 :::code-group
 ```bash [CLI]
@@ -77,6 +83,30 @@ export default defineConfig({
 ```
 :::
 
+The `json` and `junit` reporters also accept `outputFile` as a reporter option, which takes precedence over the top-level `outputFile`:
+
+```ts [vitest.config.ts]
+export default defineConfig({
+  test: {
+    reporters: [['json', { outputFile: './test-output.json' }]],
+  },
+})
+```
+
+To print the report to the terminal instead of writing it to a file, set the `stdout` option on the `json` or `junit` reporter. This is ignored when `outputFile` is set:
+
+```ts [vitest.config.ts]
+export default defineConfig({
+  test: {
+    reporters: [['json', { stdout: true }]],
+  },
+})
+```
+
+::: warning
+When `stdout` is enabled, the report can be interleaved with other output written directly to the terminal — for example `process.stdout.write` in a test file, or logs from the main process such as a global setup file — which can make the JSON or XML unparsable. Prefer the default file output when you need to consume the report programmatically.
+:::
+
 ## Combining Reporters
 
 You can use multiple reporters simultaneously to print your test results in different formats. For example:
@@ -316,7 +346,7 @@ Example terminal output for a passing test suite:
 
 ### JUnit Reporter
 
-Outputs a report of the test results in JUnit XML format. Can either be printed to the terminal or written to an XML file using the [`outputFile`](/config/outputfile) configuration option.
+Outputs a report of the test results in JUnit XML format. By default it is written to `.vitest/junit/output.xml`. To write it elsewhere, use the [`outputFile`](/config/outputfile) configuration option or the reporter's own `outputFile` option. To print it to the terminal instead, set the reporter's [`stdout`](#reporter-output) option.
 
 :::code-group
 ```bash [CLI]
@@ -420,7 +450,7 @@ export default defineConfig({
 
 ### JSON Reporter
 
-Generates a report of the test results in a JSON format compatible with Jest's `--json` option. Can either be printed to the terminal or written to a file using the [`outputFile`](/config/outputfile) configuration option.
+Generates a report of the test results in a JSON format compatible with Jest's `--json` option. By default it is written to `.vitest/json/output.json`. To write it elsewhere, use the [`outputFile`](/config/outputfile) configuration option or the reporter's own `outputFile` option. To print it to the terminal instead, set the reporter's [`stdout`](#reporter-output) option.
 
 :::code-group
 ```bash [CLI]
diff --git a/packages/vitest/src/node/reporters/json.ts b/packages/vitest/src/node/reporters/json.ts
@@ -75,6 +75,12 @@ export interface JsonTestResults {
 
 export interface JsonOptions {
   outputFile?: string
+  /**
+   * Print the report to stdout instead of writing it to a file.
+   * Ignored when {@link outputFile} is set.
+   * @default false
+   */
+  stdout?: boolean
   /** @experimental */
   filterMeta?: (key: string, value: unknown) => unknown
 }
@@ -220,15 +226,7 @@ export class JsonReporter implements Reporter {
       coverageMap: this.coverageMap,
     }
 
-    await this.writeReport(JSON.stringify(result))
-  }
-
-  /**
-   * Writes the report to an output file if specified in the config,
-   * or logs it to the console otherwise.
-   * @param report
-   */
-  async writeReport(report: string): Promise<void> {
+    const resultString = JSON.stringify(result)
     const outputFile
       = this.options.outputFile ?? getOutputFile(this.ctx.config, 'json')
 
@@ -240,11 +238,16 @@ export class JsonReporter implements Reporter {
         await fs.mkdir(outputDirectory, { recursive: true })
       }
 
-      await fs.writeFile(reportFile, report, 'utf-8')
+      await fs.writeFile(reportFile, resultString, 'utf-8')
       this.ctx.logger.log(`JSON report written to ${reportFile}`)
     }
+    else if (this.options.stdout) {
+      this.ctx.logger.log(resultString)
+    }
     else {
-      this.ctx.logger.log(report)
+      const report = this.ctx.createReport('json')
+      await report.writeFile('output.json', resultString)
+      this.ctx.logger.log(`JSON report written to ${resolve(report.root, 'output.json')}`)
     }
   }
 }
diff --git a/packages/vitest/src/node/reporters/junit.ts b/packages/vitest/src/node/reporters/junit.ts
@@ -50,6 +50,13 @@ export interface SuiteNameTemplateVariables {
 export interface JUnitOptions {
   outputFile?: string
 
+  /**
+   * Print the report to stdout instead of writing it to a file.
+   * Ignored when {@link outputFile} is set.
+   * @default false
+   */
+  stdout?: boolean
+
   /**
    * Template for the `classname` attribute of `<testcase>`.
    *
@@ -256,7 +263,13 @@ export class JUnitReporter implements Reporter {
       if (!existsSync(outputDirectory)) {
         await fs.mkdir(outputDirectory, { recursive: true })
       }
+    }
+    else if (!this.options.stdout) {
+      const report = this.ctx.createReport('junit')
+      this.reportFile = resolve(report.root, 'output.xml')
+    }
 
+    if (this.reportFile) {
       const fileFd = await fs.open(this.reportFile, 'w+')
       this.fileFd = fileFd
 
diff --git a/test/e2e/test/annotations.test.ts b/test/e2e/test/annotations.test.ts
@@ -1,7 +1,8 @@
 import type { TestAnnotation, TestArtifact } from 'vitest'
-import { readdirSync } from 'node:fs'
+import { readdirSync, readFileSync } from 'node:fs'
 import path from 'node:path'
 import { playwright } from '@vitest/browser-playwright'
+import { resolve } from 'pathe'
 import { describe, expect, test } from 'vitest'
 import { runInlineTests } from '../../test-utils'
 
@@ -371,7 +372,7 @@ describe('reporters', () => {
   })
 
   test('junit reporter prints annotations', async () => {
-    const { stdout } = await runInlineTests(
+    const { root } = await runInlineTests(
       {
         'basic.test.ts': annotationTest,
         'test-3.js': test3Content,
@@ -380,7 +381,7 @@ describe('reporters', () => {
       { reporters: ['junit'] },
     )
 
-    const result = stdout
+    const result = readFileSync(resolve(root, '.vitest/junit/output.xml'), 'utf-8')
       .replace(/time="[\d.]+"/g, 'time="0"')
       .replace(/timestamp="[\w\-:.]+"/g, 'timestamp="0"')
       .replace(/hostname="[\w.\-]+"/g, 'hostname="CI"')
diff --git a/test/e2e/test/artifacts.test.ts b/test/e2e/test/artifacts.test.ts
@@ -1,6 +1,8 @@
 import type { TestAnnotation, TestArtifact } from 'vitest'
+import { readFileSync } from 'node:fs'
 import { format } from 'node:util'
 import { playwright } from '@vitest/browser-playwright'
+import { resolve } from 'pathe'
 import { describe, expect, test } from 'vitest'
 import { runInlineTests } from '../../test-utils'
 
@@ -311,7 +313,7 @@ describe('reporters', () => {
   })
 
   test('junit', async () => {
-    const { stdout } = await runInlineTests(
+    const { root } = await runInlineTests(
       {
         'basic.test.ts': artifactsTest,
         'test-3.js': test3Content,
@@ -320,7 +322,7 @@ describe('reporters', () => {
       { reporters: ['junit'] },
     )
 
-    const result = stdout
+    const result = readFileSync(resolve(root, '.vitest/junit/output.xml'), 'utf-8')
       .replace(/time="[\d.]+"/g, 'time="0"')
       .replace(/timestamp="[\w\-:.]+"/g, 'timestamp="0"')
       .replace(/hostname="[\w.\-]+"/g, 'hostname="CI"')
diff --git a/test/e2e/test/benchmarking.test.ts b/test/e2e/test/benchmarking.test.ts
@@ -1,5 +1,7 @@
 import type { BaselineData, BenchResult, TestBenchmark, TestBenchmarkTask } from 'vitest'
 import type { JsonTestResults } from 'vitest/node'
+import { readFileSync } from 'node:fs'
+import { resolve } from 'pathe'
 import { expect, test } from 'vitest'
 import { runInlineTests } from '../../test-utils'
 
@@ -322,7 +324,7 @@ test('`bench(..., { perProject: true }, fn)` records a perProject task in the in
 })
 
 test('junit reporter embeds the benchmark table inside <system-out>', async () => {
-  const { stdout } = await runInlineTests(
+  const { root } = await runInlineTests(
     {
       'junit.bench.ts': /* ts */`
         import { test, inject } from 'vitest'
@@ -343,10 +345,12 @@ test('junit reporter embeds the benchmark table inside <system-out>', async () =
     },
   )
 
+  const xml = readFileSync(resolve(root, '.vitest/junit/output.xml'), 'utf-8')
+
   // extract the <system-out> block from the rendered XML
   // eslint-disable-next-line regexp/no-super-linear-backtracking
-  const systemOut = stdout.match(/<system-out>\s*\n([\s\S]*?)<\/system-out>/)?.[1]
-  expect(systemOut, stdout).toBeDefined()
+  const systemOut = xml.match(/<system-out>\s*\n([\s\S]*?)<\/system-out>/)?.[1]
+  expect(systemOut, xml).toBeDefined()
 
   // a header + 2 data rows — reformat through the shared helper so digits
   // collapse to `d+` and widths become measurement-independent
@@ -908,7 +912,7 @@ test('`vitest bench` CLI invocation filters to the cloned benchmark project', as
 })
 
 test('json reporter surfaces benchmarks on each assertion result', async () => {
-  const { stderr, stdout } = await runInlineTests(
+  const { stderr, root } = await runInlineTests(
     {
       'foo.bench.ts': /* ts */`
         import { test, inject } from 'vitest'
@@ -928,7 +932,7 @@ test('json reporter surfaces benchmarks on each assertion result', async () => {
     },
   )
   expect(stderr).toBe('')
-  const parsed = JSON.parse(stdout) as JsonTestResults
+  const parsed = JSON.parse(readFileSync(resolve(root, '.vitest/json/output.json'), 'utf-8')) as JsonTestResults
   const assertionResults = parsed.testResults.flatMap(tr => tr.assertionResults)
   const smoke = assertionResults.find(a => a.title === 'smoke')!
   expect(
diff --git a/test/e2e/test/reporters/json.test.ts b/test/e2e/test/reporters/json.test.ts
@@ -1,3 +1,4 @@
+import { readFileSync } from 'node:fs'
 import { runVitest } from '#test-utils'
 import { resolve } from 'pathe'
 
@@ -7,15 +8,19 @@ describe('json reporter', async () => {
   const root = resolve(import.meta.dirname, '..', '..', 'fixtures', 'reporters')
   const projectRoot = resolve(import.meta.dirname, '..', '..', '..', '..')
 
+  function readJsonReport() {
+    return JSON.parse(readFileSync(resolve(root, '.vitest/json/output.json'), 'utf-8'))
+  }
+
   it('generates correct report', async () => {
-    const { stdout } = await runVitest({
+    await runVitest({
       reporters: 'json',
       root,
       include: ['**/json-fail-import.test.ts', '**/json-fail.test.ts'],
       includeTaskLocation: true,
     }, ['json-fail'])
 
-    const data = JSON.parse(stdout)
+    const data = readJsonReport()
 
     expect(data.testResults).toHaveLength(2)
 
@@ -40,13 +45,13 @@ describe('json reporter', async () => {
   })
 
   it('generates empty json with success: false', async () => {
-    const { stdout } = await runVitest({
+    await runVitest({
       reporters: 'json',
       root,
       includeTaskLocation: true,
     }, ['json-non-existing-files'])
 
-    const json = JSON.parse(stdout)
+    const json = readJsonReport()
     json.startTime = 0
     expect(json).toMatchInlineSnapshot(`
       {
@@ -83,14 +88,14 @@ describe('json reporter', async () => {
   })
 
   it('generates empty json with success: true', async () => {
-    const { stdout } = await runVitest({
+    await runVitest({
       reporters: 'json',
       root,
       includeTaskLocation: true,
       passWithNoTests: true,
     }, ['json-non-existing-files'])
 
-    const json = JSON.parse(stdout)
+    const json = readJsonReport()
     json.startTime = 0
     expect(json).toMatchInlineSnapshot(`
       {
@@ -131,42 +136,56 @@ describe('json reporter', async () => {
     ['passed', 'all-skipped.test.ts'],
     ['failed', 'some-failing.test.ts'],
   ])('resolves to "%s" status for test file "%s"', async (expected, file) => {
-    const { stdout } = await runVitest({ reporters: 'json', root, include: [`**/${file}`] })
+    await runVitest({ reporters: 'json', root, include: [`**/${file}`] })
 
-    const data = JSON.parse(stdout)
+    const data = readJsonReport()
 
     expect(data.testResults).toHaveLength(1)
     expect(data.testResults[0].status).toBe(expected)
   })
 
   it('includes all meta fields when filterMeta is not set', async () => {
-    const { stdout } = await runVitest({
+    await runVitest({
       reporters: 'json',
       root,
       include: ['**/json-meta.test.ts'],
     })
 
-    const data = JSON.parse(stdout)
+    const data = readJsonReport()
     const results = data.testResults[0].assertionResults
     const passing = results.find((r: any) => r.title === 'pass')
 
     expect(passing.meta).toEqual({ custom: 'Passing test added this' })
   })
 
   it('filterMeta filters meta fields by key', async () => {
-    const { stdout } = await runVitest({
+    await runVitest({
       reporters: [['json', {
         filterMeta: key => key !== 'custom',
       }]],
       root,
       include: ['**/json-meta.test.ts'],
     })
 
-    const data = JSON.parse(stdout)
+    const data = readJsonReport()
     const results = data.testResults[0].assertionResults
 
     for (const result of results) {
       expect(result.meta).toEqual({})
     }
   })
+
+  it('prints report to stdout when stdout option is set', async () => {
+    const { stdout } = await runVitest({
+      reporters: [['json', { stdout: true }]],
+      root,
+      include: ['**/ok.test.ts'],
+    })
+    const data = JSON.parse(stdout)
+    expect(data).toMatchObject({
+      numTotalTests: 1,
+      numPassedTests: 1,
+      success: true,
+    })
+  })
 })
diff --git a/test/e2e/test/reporters/junit.test.ts b/test/e2e/test/reporters/junit.test.ts
diff --git a/test/e2e/test/reporters/merge-reports.test.ts b/test/e2e/test/reporters/merge-reports.test.ts
diff --git a/test/e2e/test/reporters/reporters.test.ts b/test/e2e/test/reporters/reporters.test.ts
diff --git a/test/e2e/test/rollup-error.test.ts b/test/e2e/test/rollup-error.test.ts
