Typer Cli Testing

The goal is maximum E2E coverage - test the CLI interface, not just the underlying logic.

Topics Index

Getting Started

• clirunner.md - CliRunner constructor, parameters
• invocation.md - runner.invoke() parameters
• result-object.md - Result object attributes (exit_code, output, stdout, stderr, exception, exception_info)
• basic-testing.md - Basic testing patterns

Core Testing Topics

• exit-codes.md - Exit code testing (0, 1, 2, 125, 126, 127, 130)
• output-verification.md - stdout/stderr verification
• prompts-testing.md - Testing prompts (input, order, retry)
• subcommands-testing.md - Testing subcommands and nested commands
• callbacks-testing.md - Testing callbacks, invoke_without_command
• context-testing.md - Testing Context (ctx.obj, ctx.params)

Advanced Topics

• isolated-filesystem.md - isolated_filesystem() usage
• file-operations.md - Testing file operations
• exception-testing.md - Testing result.exception, exception_info
• mix-stderr.md - mix_stderr parameter and behavior
• progressbar-testing.md - Testing progress bars
• rich-output-testing.md - Testing Rich markup output

Testing Infrastructure

• mocking.md - Mocking patterns (os.getenv, typer.launch, Path)
• pytest-configuration.md - conftest.py, fixtures, pytest.ini
• parametrization.md - pytest.mark.parametrize
• integration-testing.md - Integration tests (subprocess)
• coverage.md - pytest-cov configuration
• parallel-tests.md - Parallel testing with isolated_filesystem

Reference

• troubleshooting.md - Troubleshooting guide
• anti-patterns.md - Anti-patterns
• common-mistakes.md - Common mistakes checklist

Examples

• examples/sample.md - Complete sample application and tests

Related Skills

Testing Workflow

1. Write the test first - TDD approach for CLI development
2. Run the test - Verify it fails for the right reason
3. Implement the feature - Make the test pass
4. Add edge cases - Test failure modes
5. Refactor - Ensure tests still pass

Senior Advice

"Test the CLI interface, not the implementation. If you refactor the internals, your tests should still pass."

"Every runner.invoke() without an exit_code check is a silent failure waiting to happen. Be explicit."

"If a command has a prompt, it MUST have a test with input=. No exceptions. A prompt without a test is untested user input."

"The difference between a test that catches bugs and one that doesn't often comes down to checking the failure case, not just the happy path."

"When writing CLI tests, think from the user's perspective: What could go wrong? What should happen then? Write tests for those scenarios."

"A test that doesn't verify exit codes is like a test that doesn't assert anything - it gives you false confidence."

External Resources

• Typer Testing Documentation: https://typer.tiangolo.com/tutorial/testing/
• CliRunner API: https://typer.tiangolo.com/api/typer/testing/
• pytest Documentation: https://docs.pytest.org/

Note: This skill teaches how to write tests. The existing typer-test-quality-skill evaluates existing tests. Use both together: write tests with this skill, then evaluate them with the quality skill.