feat(reporters)!: write json and junit reporter output files to `.vitest` by default by hi-ogawa · Pull Request #10621 · vitest-dev/vitest

hi-ogawa · 2026-06-19T07:57:56Z

Description

closes Make json and junit reporters default output use .vitest as the report artifact root #10619

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The `json` and `junit` reporters now write to `.vitest/json/output.json` and `.vitest/junit/output.xml` when no `outputFile` is configured, instead of printing to stdout. This aligns them with the `.vitest/` artifact convention and the `blob` reporter, and produces an on-disk artifact by default. Explicit `outputFile` is unchanged. BREAKING CHANGE: json/junit reporters no longer print to stdout by default. Read the generated artifact file instead (e.g. `jq . .vitest/json/output.json`). Closes vitest-dev#10619 AI-Agent: Opencode

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Add a migration guide section documenting that the json and junit reporters now write to `.vitest/json/output.json` and `.vitest/junit/output.xml` by default instead of printing to stdout. Also revert the outputFile config doc, which is handled separately. AI-Agent: Opencode

AI-Agent: Opencode

The html reporter location change is handled separately; keep its existing outputFile behavior and scope the .vitest defaults to the json and junit reporters only. AI-Agent: Opencode

AI-Agent: Opencode

sheremet-va · 2026-06-19T08:29:27Z


+### Generated Reports and Artifacts Use the `.vitest` Directory
+
+Vitest now uses a single `.vitest` directory at the project root as the shared artifact root. The `json` and `junit` reporters now write to this directory by default instead of printing to stdout:


What is wrong with printing to stdout? Why do we remove this completely?

For the use case I understand, they look effectively useless and misguided. See #10619

In practice, "print to stdout" pushes users into awkward workarounds to get the file they actually wanted. Common patterns in the wild:

Redirect to a file, then upload as a CI artifact: vitest run --reporter=json > vitest-report.json then upload it (e.g. mizchi/flaker .github/workflows/ci.yml, which redirects → uploads → re-imports the report in a later job).

Pipe into a post-processor: vitest --reporter=json | jq '.numFailedTests'.

Redirect a bench/report run: vitest bench --run --reporter=json > benchmark-results.json (e.g. thibmeu/act-ts).

A scoped .vitest/ default serves all of these better, with zero config:

Artifact upload: just run vitest --reporter=json and upload .vitest/json/output.json — no redirect.

Post-analysis: jq '.numFailedTests' .vitest/json/output.json — and it's re-runnable without re-running the tests, since the artifact persists.

So the stdout default isn't a feature these workflows rely on; it's the limitation they work around. Moving to .vitest/ removes the workaround.

Did we discuss maybe supporting outputFile: "-" to mean stdout?

So the stdout default isn't a feature these workflows rely on; it's the limitation they work around. Moving to .vitest/ removes the workaround.

This seems weird - if it's so much better to keep a file, why don't they use --outputFile and read from it? Just because it's not a default?

So the stdout default isn't a feature these workflows rely on; it's the limitation they work around. Moving to .vitest/ removes the workaround.

This seems weird - if it's so much better to keep a file, why don't they use --outputFile and read from it? Just because it's not a default?

This is just my educated guess and basically my biased opinion.

Also I prefer the file because direct stdout writing such as process.stdout.write can break stdout redirection approach (or console.log in main process like global setup).

These suites asserted on stdout, which no longer carries the junit report now that it is written to .vitest/junit/output.xml by default. AI-Agent: Opencode

The default-mode json/junit reporter tests asserted on the captured logger output, which now only contains the "report written" log line. Teach the mock getContext() to provide createReport() backed by a temp directory and read the generated artifact instead. AI-Agent: Opencode

# Conflicts: # docs/guide/migration.md # docs/guide/reporters.md

AI-Agent: Opencode

The rollup-error e2e suite only needed a sink to grep the surfaced resolve errors; the default reporter prints them to stderr, so drop the junit reporter dependency (and the .vitest report file read) and assert the unescaped error text directly. AI-Agent: Opencode

AI-Agent: Opencode

AriPerkkio

Looks good to me. I don't think stdout as JSON or Junit output ever made sense. The output could have contained Node's and Vitest's deprecation warnings, so parsing the XML/JSON from there would be difficult.

AriPerkkio · 2026-06-23T05:16:01Z

+- `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) either in your Vite configuration file or via CLI; the `html` reporter uses its [`outputDir`](#html-reporter) option instead.


Do we mention outputFile reporter option anywhere?

vitest/packages/vitest/src/node/reporters/junit.ts

Lines 50 to 51 in c409014

export interface JUnitOptions {

outputFile?: string

I would rather start pointing users to configure this via reporter options and remove whole top level outputFile in future.

It looks like there was never a mention of ['json', { outputFile: ... }] nor junit. Will add some in the doc.

I agree that curent ouptutFile option system are rather scattered, but not sure we can drop whole top level one. Before dropping it, probably we need reporter option from cli like --reporter.json.outputFile=... somehow.

tweaked docs and created cli reporter option request #10650

AriPerkkio · 2026-06-23T05:24:42Z

+    this.baseLog = async (text: string) => {
+      if (!this.fileFd) {
+        this.fileFd = await fs.open(this.reportFile!, 'w+')
      }
-    }
-    else {
-      this.baseLog = async (text: string) => this.ctx.logger.log(text)
+
+      await fs.writeFile(this.fileFd, `${text}\n`)


Out-of-scope of this PR, but probably good refactoring for future:
I'm not exactly sure why this reporter was built to stream its results into the output file, while everything is still handled in onTestFinished. Maybe to avoid OOMs? Anyway, we could move this whole fileId initialization in onTestFinished and keep it in function scope there.

sheremet-va · 2026-06-23T05:41:16Z

I don't think stdout as JSON or Junit output ever made sense

warnings are in stderr though. jest actually forwards every log to stderr so that json reporter is parsable

hi-ogawa · 2026-06-23T06:13:52Z

I don't think stdout as JSON or Junit output ever made sense

warnings are in stderr though. jest actually forwards every log to stderr so that json reporter is parsable

How comprehensive is this though? Does any user code on main process stdout gets collected and redirected to stderr like global setup?

AriPerkkio · 2026-06-23T06:21:28Z

Does any user code on main process stdout gets collected and redirected to stderr like global setup?

No, not even from test runner workers. If you have process.stdout.write('\n\n\n\nHello world\n\n\n\n') in a test file, the final JSON will be broken:

Co-authored-by: OpenCode (claude-opus-4-8) <[email protected]>

sheremet-va · 2026-06-23T11:39:03Z

This argument feels weird to me thought. I am not against changing the default, but I am unsure why we need to take away the stdout output. It feels like a natural programmatic way to use it in a terminal - just because user can manually break it doesn’t mean it’s vitest fault. We allow custom reporters even though they can throw an error.

sheremet-va · 2026-06-23T11:39:51Z

I would keep it as —stdout flag or something. Maybe —reporter.json.stdout like Ari wanted for other reporter options

AriPerkkio

If reading JSON and XML from terminal output is expected use case, let's keep it. I cannot see when it would be useful though.

hi-ogawa · 2026-06-24T00:07:55Z

I also suggested this thing outputFile: "-" to mean stdout #10621 (comment). This feels too stretched overload, so will go with new stdout option then.

Allow opting back into printing the json/junit report to the terminal via a per-reporter `stdout` option, now that the default writes to a file under `.vitest/`. Ignored when `outputFile` is set. Co-authored-by: OpenCode (claude-opus-4-8) <[email protected]>

Co-authored-by: OpenCode (claude-opus-4-8) <[email protected]>

Revert the createReport temp-dir plumbing in getContext() now that the json/junit reporters support a `stdout` option, and drop the redundant explicit default reporter in rollup-error e2e tests. Co-authored-by: OpenCode (claude-opus-4-8) <[email protected]>

Co-authored-by: Ari Perkkiö <[email protected]>

hi-ogawa added 5 commits June 19, 2026 17:03

test: use readFileSync to read json/junit report artifacts

44a83d8

AI-Agent: Opencode

docs: drop html reporter from .vitest default description

1e26985

The html reporter location change is handled separately; keep its existing outputFile behavior and scope the .vitest defaults to the json and junit reporters only. AI-Agent: Opencode

nit

de94354

test: use single-string .vitest report paths

8122eb6

AI-Agent: Opencode

sheremet-va reviewed Jun 19, 2026

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hi-ogawa added 2 commits June 19, 2026 18:58

test: read junit report file in rollup-error/annotations/artifacts e2e

a27b269

These suites asserted on stdout, which no longer carries the junit report now that it is written to .vitest/junit/output.xml by default. AI-Agent: Opencode

hi-ogawa commented Jun 19, 2026

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Comment thread test/e2e/test/rollup-error.test.ts

hi-ogawa added 4 commits June 19, 2026 19:07

Merge remote-tracking branch 'upstream/main' into fix/issue-10619

b5afefe

# Conflicts: # docs/guide/migration.md # docs/guide/reporters.md

docs: list html .vitest/index.html in reporter output section

ab60099

AI-Agent: Opencode

chore: remove accidentally committed html test artifacts

9ecb2f2

AI-Agent: Opencode

hi-ogawa marked this pull request as ready for review June 20, 2026 08:09

Merge branch 'main' into fix/issue-10619

46fa290

hi-ogawa requested review from AriPerkkio and sheremet-va June 23, 2026 04:40

AriPerkkio previously approved these changes Jun 23, 2026

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hi-ogawa mentioned this pull request Jun 23, 2026

Support passing reporter options via CLI #10650

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docs: document per-reporter outputFile option for json and junit

0630060

Co-authored-by: OpenCode (claude-opus-4-8) <[email protected]>

hi-ogawa dismissed AriPerkkio’s stale review via 0630060 June 23, 2026 08:46

AriPerkkio approved these changes Jun 23, 2026

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AriPerkkio requested changes Jun 23, 2026

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Merge branch 'main' into fix/issue-10619

ebb3ae0

hi-ogawa commented Jun 24, 2026

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Comment thread test/e2e/test/rollup-error.test.ts Outdated

Comment thread test/e2e/test/reporters/utils.ts Outdated

Comment thread test/e2e/test/reporters/json.test.ts

hi-ogawa and others added 3 commits June 24, 2026 09:32

docs: note stdout opt-in in json/junit migration entry

3c8e97b

Co-authored-by: OpenCode (claude-opus-4-8) <[email protected]>

test: add stdout option smoke tests for json and junit reporters

df54df4

Co-authored-by: OpenCode (claude-opus-4-8) <[email protected]>

sheremet-va previously approved these changes Jun 24, 2026

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hi-ogawa requested a review from AriPerkkio June 24, 2026 08:14

AriPerkkio previously approved these changes Jun 25, 2026

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Comment thread docs/guide/reporters.md Outdated

docs: Update docs/guide/reporters.md

53c69c4

Co-authored-by: Ari Perkkiö <[email protected]>

hi-ogawa dismissed stale reviews from AriPerkkio and sheremet-va via 53c69c4 June 25, 2026 06:24

AriPerkkio approved these changes Jun 25, 2026

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hi-ogawa merged commit 5857729 into vitest-dev:main Jun 25, 2026
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hi-ogawa deleted the fix/issue-10619 branch June 25, 2026 06:51


		### Generated Reports and Artifacts Use the `.vitest` Directory

		Vitest now uses a single `.vitest` directory at the project root as the shared artifact root. The `json` and `junit` reporters now write to this directory by default instead of printing to stdout:

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