Workflows

Failed Test Workflow

When tests fail, failed test locations are automatically saved. Re-run only the failures:

check --only test     # Run tests, failures saved automatically
check --failed        # Re-run only the failed tests
check --failed --repeat 10  # Re-run with repeat

Failed tests are saved to .check/failed_tests.txt. Failures are extracted from both test partition outputs and any custom check output (e.g. modified_tests).

Auto-fix Workflow

Run checks first to store output, then apply fixes:

check --only format,credo  # Run checks and store output
check --fix                # Apply fixes from stored output

Fix commands are configurable in .check.json:

"fix": [
  {"run": "mix format"},
  {"run": "mix recode", "files": ".check/credo*.txt"}
]

Modified Tests Workflow

Run only tests that changed on your branch vs the base branch:

check --only modified_tests           # Run only changed test lines
check --only modified_test_modules    # Run whole changed test files
check --only modified_tests --repeat 5  # Repeat modified tests

modified_tests uses granular detection:

Module-level setup changed → runs the whole file
Setup inside describe changed → runs that describe block
Describe line changed → runs that describe block
Test body changed → runs only that specific test line

modified_test_modules is simpler - runs the entire file for any changed test module.

Coverage Workflow

Show coverage report (cached if cover/ data hasn't changed):

check --coverage       # Show coverage report (cached if cover/ unchanged)
check --no-coverage    # Run checks without coverage (overrides .check.json)

Coverage is also merged automatically after partitioned test runs. Configure in .check.json:

"coverage": {
  "mod": "native",
  "limit": 80,
  "html": false,
  "baseline_cmd": "git show origin/main:coverage.txt"
}

When baseline_cmd is set, shows delta vs baseline:

✓ Coverage: 85.5% | Report: cover/
  Coverage: +2.3% vs baseline (83.2%)

Database Setup for Partitions

Set up or drop databases for all test partitions in parallel:

check --setup-db                          # mix ecto.setup for each partition
check --drop-db                           # mix ecto.drop for each partition
check --setup-db --partitions 6           # with custom partition count
check --for-partitions 'mix ecto.reset'   # any command across partitions
check --for-partitions 'mix ecto.migrate' --partitions 4

--db-setup and --db-drop are also accepted as aliases.

Commands are configurable in .check.json:

"db_setup": "mix ecto.setup",
"db_drop": "mix ecto.drop"

Each partition runs with MIX_ENV=test MIX_TEST_PARTITION=N prepended.

Updating AlCheck

mix check.update

Runs the commands defined in "update" in .check.json, or defaults to:

mix deps.update al_check
mix check.install

Add your version manager's reshim command:

"update": [
  "mix deps.update al_check",
  "mix check.install",
  "asdf reshim"
]

Watch Mode

Monitor test partition output files in real-time while tests run in another terminal:

check --watch

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