write-tests

name	write-tests
description	Use this skill when creating or updating tests in this repository.

Write Tests

Scope

• Apply these patterns when adding or editing tests in this repository.
• Use existing test style and keep test changes focused on behavior.

Commands

• Run tests with mise run test.
• Update snapshots with mise run update-snapshots.

Testing Patterns

• Unit tests use testify/assert alongside source files
• UI components use snapshot testing (go-snaps); snapshots in internal/ui/__snapshots__/
• internal/types has a TimeProvider interface for mocking time in tests
• CLI integration tests use Go tests in tests/cli with snapshots in tests/cli/__snapshots__/

CLI integration tests

• Keep integration tests in package tests/cli (file-per-command is preferred)
• TestMain builds the hours binary once per package run and is shared by all tests in the package
• NewFixture(t, testBinaryPath) gives each test a t.TempDir() workspace (auto-cleaned)
• Use cmd.UseDB() to append a per-test DB path under the fixture temp dir
• RunCmd executes with timeout and deterministic env (HOME set to fixture temp dir, PATH propagated, explicit overrides via SetEnv)

Given-When-Then Structure

All tests in this codebase should follow the Given-When-Then (GWT) pattern to improve readability and maintainability. This structure makes tests self-documenting and helps both humans and AI agents quickly understand:

• What state is being set up (Given)
• What action is being performed (When)
• What outcome is expected (Then)

Format:

func TestSomething(t *testing.T) {
    // GIVEN
    // ... setup code, test data, initial state

    // WHEN
    // ... the action being tested

    // THEN
    // ... assertions and expected outcomes
}

Snapshot tests

• Use snapshot tests with go-snaps wherever it makes sense, especially for:
  • Complex data structures (serialization/deserialization)
  • Generated output (TUI frames, command line output, etc.)
  • Regression testing where exact output matters