TypeScript / Type Check

Run a type-checker (tsc --noEmit, mypy, pyright, flow) without running tests.

Reference: loha/type-check@v1

Category: test

Runtime: docker.io/library/node:20-alpine (non-root, digest-pinned at Node 20)

License: Apache-2.0

When to use

Use this step alongside run-lint and run-tests for full static + dynamic coverage. Type-checking is intentionally separate from linting because the failure modes are different and the checks parallelize well.

Parameters

Parameter	Type	Default	Required	Description
CHECK_COMMAND	string	npx tsc --noEmit	No	Type-check command to execute. For TypeScript: npx tsc --noEmit, pnpm type-check. For Python: mypy ., pyright.
WORKING_DIRECTORY	string	.	No	Directory to run in, relative to workspace root. Use for monorepo subdirectories.
CHECK_IMAGE	string	docker.io/library/node@sha256:fb4cd12c85ee03686f6af5362a0b0d56d50c58a04632e6c0fb8363f609372293	No	Container image with type-check tool installed. Use node:20-alpine for TS, python:3.12-slim for mypy/pyright.
FAIL_ON_ERROR	enum: true, false	true	No	Fail the step if type errors are found.

Workspaces

• source (required): bound from pipeline workspace source

Results

Result	Description
CHECK_RESULT	PASS or FAIL
ERROR_COUNT	Number of type errors found

How it works

Runs CHECK_COMMAND inside CHECK_IMAGE under WORKING_DIRECTORY. Default is npx tsc --noEmit on node:20-alpine for TypeScript projects. Exit code drives CHECK_RESULT; ERROR_COUNT is best-effort parsed from tsc/mypy/pyright output.

Examples

TypeScript monorepo app

steps:
  - name: type-check
    uses: loha/type-check@v1
    with:
      CHECK_COMMAND: 'pnpm type-check'
      WORKING_DIRECTORY: 'apps/dashboard'

Python with mypy

steps:
  - name: type-check
    uses: loha/type-check@v1
    with:
      CHECK_COMMAND: 'mypy src/ --ignore-missing-imports'
      CHECK_IMAGE: 'python:3.12-slim'

Troubleshooting

Problem: tsc: command not found.

Solution: Add typescript as a dev-dependency in your project so the workspace install pulls it in, or use a custom CHECK_IMAGE with TypeScript pre-installed.

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Problem: Type errors in node_modules flood the output.

Solution: Add "exclude": ["node_modules"] to your tsconfig.json or pass --skipLibCheck to tsc.