cli(test): --coverage-reporter and --coverage-dir imply --coverage

[robobun]

Fixes #17502.

Repro

$ bun test --coverage-reporter=lcov
bun test v1.4.0
(pass) add
 1 pass
$ ls coverage/
ls: cannot access 'coverage/': No such file or directory

No coverage output is produced unless --coverage is also passed.

Cause

src/runtime/cli/Arguments.rs parses --coverage-reporter and --coverage-dir into ctx.test_options.coverage.{reporters,reports_directory} but never sets coverage.enabled, so the test runner skips coverage collection entirely.

Fix

Set ctx.test_options.coverage.enabled = true when either --coverage-reporter or --coverage-dir is passed on the CLI.

The bunfig keys (coverageReporter, coverageDir) are intentionally left as-is: a preconfigured reporter in bunfig.toml shouldn't force coverage on every bun test run. Users who want that already have coverage = true.

Verification

New tests in test/cli/test/coverage.test.ts:

• --coverage-reporter=lcov / --coverage-reporter lcov alone writes coverage/lcov.info
• --coverage-reporter=text alone prints the coverage table
• --coverage-dir=out alone prints the coverage table (default text reporter)

All four fail on main and pass with this change. Full coverage.test.ts suite (16 tests) passes.

[robobun]

^{Updated 3:40 PM PT - Jun 16th, 2026}

❌ @autofix-ci[bot], your commit 4f2c2f0 has 1 failures in Build #62941 (All Failures):

• Failed to create agent for :freebsd: aarch64 - build-rust
• Failed to create agent for 🐧 aarch64-android - build-rust
• Failed to create agent for 🐧 x64-musl - build-rust
• Failed to create agent for 🐧 x64-baseline - build-cpp
• Failed to create agent for 🐧 aarch64-musl - build-rust
• Failed to create agent for 🍎 x64 - build-cpp
• Failed to create agent for 🐧 aarch64-android - build-cpp
• Failed to create agent for 🐧 aarch64 - build-cpp
• Failed to create agent for 🐧 x64 - build-rust
• Failed to create agent for 🪟 x64 - build-cpp
• Failed to create agent for 🐧 x64-android - build-rust
• Failed to create agent for 🪟 x64 - build-rust
• Failed to create agent for 🪟 aarch64 - build-cpp
• Failed to create agent for 🐧 x64-baseline - build-rust
• Failed to create agent for 🪟 x64-baseline - build-rust
• Failed to create agent for 🐧 x64-asan - build-rust
• Failed to create agent for 🐧 aarch64-musl - build-cpp
• Failed to create agent for 🍎 aarch64 - build-cpp
• Failed to create agent for 🐧 x64-musl-baseline - build-rust
• Failed to create agent for :freebsd: x64 - build-rust
• Failed to create agent for 🍎 x64 - build-rust
• Failed to create agent for 🐧 x64-musl - build-cpp
• Failed to create agent for 🪟 aarch64 - build-rust
• Failed to create agent for 🪟 x64-baseline - build-cpp
• Failed to create agent for 🐧 x64 - build-cpp
• Failed to create agent for 🐧 aarch64 - build-rust
• Failed to create agent for 🍎 aarch64 - build-rust
• Failed to create agent for :freebsd: x64 - build-cpp
• Failed to create agent for :freebsd: aarch64 - build-cpp
• Failed to create agent for 🐧 x64-android - build-cpp
• Failed to create agent for 🐧 x64-asan - build-cpp
• Failed to create agent for 🐧 x64-musl-baseline - build-cpp
• Failed to create agent for 📦 binary-size

---

🧪   To try this PR locally:

bunx bun-pr 32420

That installs a local version of the PR into your bun-32420 executable, so you can run:

bun-32420 --bun

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 4f5f1cb and 4f2c2f0.

📒 Files selected for processing (2)

• docs/snippets/cli/test.mdx
• src/runtime/cli/Arguments.rs

---

Walkthrough

parse_test_command_options in Arguments.rs gains two lines that unconditionally set coverage.enabled = true when --coverage-reporter or --coverage-dir is parsed, with updated help text clarifying each flag implies --coverage. Documentation and integration tests confirm the implied behavior.

Changes

Implicit Coverage Activation

Layer / File(s)	Summary
Implicit coverage enable in argument parser src/runtime/cli/Arguments.rs	Updates help text for --coverage-reporter and --coverage-dir to indicate "Implies --coverage". Sets ctx.test_options.coverage.enabled = true before the --coverage-reporter handler (line 1566) and before the --coverage-dir handler (line 1622), activating coverage without requiring an explicit --coverage flag.
Documentation updates for coverage flags docs/snippets/cli/test.mdx	Documents that --coverage-reporter reports text and/or lcov (defaulting to text) and implies --coverage. Notes that --coverage-dir also implies --coverage.
Integration tests for implied coverage flags test/cli/test/coverage.test.ts	Adds existsSync to the fs import. Adds a test.each block for multiple --coverage-reporter forms asserting coverage/lcov.info is created with the expected LCOV source entry. Adds tests for --coverage-reporter=text and --coverage-dir=out asserting stderr contains coverage summary markers (% Funcs, % Lines) and the tested filename.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and specifically describes the main change: enabling coverage implicitly when reporter or directory flags are used.
Description check	✅ Passed	The description comprehensively covers the issue, root cause, fix, and verification with clear examples and test cases.
Linked Issues check	✅ Passed	The PR fully addresses issue #17502 by making --coverage-reporter and --coverage-dir imply --coverage, resolving the exact user experience gap described.
Out of Scope Changes check	✅ Passed	All changes are scoped to fixing #17502: CLI parsing logic updates, help text clarification, and targeted test coverage for the new behavior.

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[robobun]

CI is currently blocked on agent provisioning (Image not found: linux-*-v37) across all lanes and branches including main; no build or test job has run against this diff. The change itself is two lines in Arguments.rs plus tests, verified green locally (bun bd test test/cli/test/coverage.test.ts, 16/16 pass). Ready for review/re-run once agents recover.

[claude]

LGTM — two-line flag-implication fix with matching integration tests; the help-text note is a non-blocking nit.

Extended reasoning...

Overview

This PR adds two lines to parse_test_command_options in src/runtime/cli/Arguments.rs, setting ctx.test_options.coverage.enabled = true inside the existing --coverage-reporter and --coverage-dir handlers. It also adds four integration tests in test/cli/test/coverage.test.ts (plus an existsSync import) verifying that each flag now produces coverage output without an explicit --coverage. Fixes #17502.

Security risks

None. This is a CLI ergonomics change in the test runner's argument parser — no auth, crypto, filesystem-permission, or network surface is touched. The only behavioral effect is enabling coverage instrumentation when the user has already signaled coverage intent via a related flag.

Level of scrutiny

Low. The change is mechanical and follows established precedent in the same function: --seed already sets randomize = true, and --parallel already sets isolate = true. The new assignments sit inside pre-existing if blocks, so no new control flow is introduced. The PR description explicitly justifies leaving the bunfig equivalents (coverageReporter, coverageDir) untouched, which is the right call — a preconfigured reporter shouldn't force coverage on every bun test.

Other factors

• Neither file is covered by CODEOWNERS.
• The new tests mirror existing patterns in coverage.test.ts (tempDirWithFiles, bunExe(), bunEnv, spawnSync) and assert on both lcov-file and text-table outputs.
• CI failures are infrastructure-only ("Failed to create agent" / image-not-found across all lanes including main); the author reports the full coverage.test.ts suite (16 tests) passes locally.
• The only bug-hunter finding is a documentation nit suggesting "Implies --coverage." be appended to the help strings — worth doing but not a blocker.

[claude]

LGTM — thanks for adding the "Implies --coverage." help text.

Extended reasoning...

Overview

Two-line functional change in src/runtime/cli/Arguments.rs: when --coverage-reporter or --coverage-dir is parsed, set ctx.test_options.coverage.enabled = true. Accompanying help-string updates in TEST_ONLY_PARAMS, a matching docs snippet update in docs/snippets/cli/test.mdx, and four new integration tests in test/cli/test/coverage.test.ts covering both = and space-separated forms plus the --coverage-dir case.

Security risks

None. This is CLI flag parsing for the test runner's coverage feature; no auth, crypto, filesystem-path, or untrusted-input handling is altered. The new assignments only flip a boolean that was already settable via the existing --coverage flag.

Level of scrutiny

Low. The functional diff is two unconditional boolean assignments inside existing if blocks that already guard on the flag being present. There is no --no-coverage flag to conflict with, and the existing --coverage handling at line 1561-1562 already only writes when not previously enabled, so ordering/override concerns don't apply. The bunfig path is intentionally untouched per the PR description, which is the right call. None of the touched files are CODEOWNER-protected.

Other factors

My earlier nit (document the implication in help text) was addressed in c67cec2 and the inline thread is resolved. The bug-hunting pass found nothing. New tests follow the established tempDirWithFiles + Bun.spawnSync pattern from the same file and assert on observable behavior (lcov.info on disk, % Funcs/% Lines in stderr). The CI failure is fleet-wide agent provisioning (Image not found: linux-*-v37), unrelated to this diff, and the suite was verified green locally per the author.

[robobun]

Stale PR review: keep open, rework.

The --coverage-reporter half of this PR is wanted. #17502 is open, and a maintainer asked for the fix there on 2026-06-16. On main, bun test --coverage-reporter=lcov still writes no report, because src/runtime/cli/Arguments.rs:1759-1761 reads only --coverage. #20736 made the same one-line change and was closed only because it predated the Rust rewrite.

The --coverage-dir half does not fit. #17502, #17737 and #20736 cover --coverage-reporter only. Only the lcov writer reads reports_directory (src/runtime/cli/test_command.rs:1627-1677), so bun test --coverage-dir=out alone would print the text table and never create out/. The comparable flags --cpu-prof-dir and --heap-prof-dir do not turn their switch on. They fail with "must be used with --cpu-prof" (Arguments.rs:1357, :1414).

Wanted shape:

• Rebase on main. The branch conflicts.
• Keep coverage.enabled = true in the --coverage-reporter block, with its help text, its docs line and its tests.
• Drop the --coverage-dir enable line, with its help text, its docs line and its test.

[robobun]

Closing as part of a cleanup of stale pull requests. This PR has had no new commits since 2026-06-16, it conflicts with main, and its last CI run failed. This is not a judgment on the fix itself. The linked issue (#17502) stays open. If the problem still reproduces on a current build, reopen this PR after a rebase or open a new one against main.