test-changes - SKILL.md Agent Skill

name: test_changes description: Run Jest unit tests for files changed in the current branch arguments:

name: scope description: "What to diff against: 'branch' (vs base branch, default), 'staged' (staged only), 'unstaged' (unstaged only), 'all-local' (staged + unstaged)" required: false
name: base description: "Base ref to diff against when scope=branch (default: auto-detects remote main/mainline)" required: false

Run Changed Tests

Find and run Jest tests relevant to locally changed files.

Process

Step 1: Determine changed files

Based on the scope argument (default: branch):

# scope=branch (default): all changes since diverging from base branch
# Auto-detect base: use origin/main or origin/mainline, whichever exists
base="${base:-$(git rev-parse --verify origin/main 2>/dev/null && echo origin/main || echo origin/mainline)}"
git diff --name-only --diff-filter=ACMR "$base"...HEAD
# Also include uncommitted changes on top
git diff --name-only --diff-filter=ACMR HEAD

# scope=staged
git diff --cached --name-only --diff-filter=ACMR

# scope=unstaged
git diff --name-only --diff-filter=ACMR

# scope=all-local
git diff --name-only --diff-filter=ACMR HEAD

Filter to only .ts, .tsx, .js, .jsx files. Exclude files under target/, build/, node_modules/.

Step 2: Separate source files and test files

From the changed file list:

Test files: any file matching *.test.ts, *.test.tsx, *.test.js, *.test.jsx → run directly.
Source files: everything else → look for a corresponding test file.

Step 3: Find test files for changed source files

For each changed source file (e.g., src/plugins/foo/bar.ts), check if any of these exist:

src/plugins/foo/bar.test.ts
src/plugins/foo/bar.test.tsx
src/plugins/foo/bar.test.js

Use the first match found.

Step 4: Warn about missing tests

For any changed source file with no matching test file, print a warning:

⚠ No test file found for: src/plugins/foo/bar.ts

This is informational only — do not fail or block.

Step 5: Run tests

Combine all discovered test files (from changed test files + matched test files for source changes), deduplicate, then run:

yarn test:jest path/to/test1.test.ts path/to/test2.test.tsx ...

If no test files are found at all, report that and exit cleanly.

Step 6: Report results

Summarize:

How many test files were run
Which changed source files had no tests (the warnings from step 4)
Pass/fail status from Jest