testify

Testify

Write new tests or improve existing ones, always reusing the project's established testing patterns, style of writing, mocks, and fixtures.

Files and instructions: $ARGUMENTS

Core principles

Reuse before creating

• Before writing any mock, fixture, factory, or helper, search the codebase for how other tests solve the same problem. If the project already has a pattern for it, use it
• Follow the mocking strategy already established (module mocks, dependency injection, HTTP interception, etc.). Only introduce a different approach when the existing one genuinely cannot cover the case
• Reuse existing test data builders and factories. If no factory exists and the same setup appears in multiple places, extract one into the project's shared test utilities

Mocking

• Mock only what is needed — not the entire module. Keep mocks scoped to the dependency being isolated
• Do not mock the unit under test
• Clean up mocks after each test to prevent leakage between tests

Structure and isolation

• Apply arrange-act-assert. Each test should verify a single behaviour
• Name tests to describe the scenario and expected outcome, not the implementation detail
• Eliminate shared mutable state between tests. Use per-test setup (beforeEach) over shared setup (beforeAll) unless the data is truly static
• Remove order dependencies between tests

Assertions

• Use specific assertions (toBe(expected), assertEqual(result, expected)) over vague ones (toBeTruthy, assert result)
• Every test should verify a concrete outcome — if code runs but nothing is asserted, add the missing assertion

Test data

• Extract hardcoded magic values into named constants or factory functions
• Reuse existing fixtures and builders from the project instead of duplicating setup

Robustness

• Replace time-dependent logic with mocked clocks
• Replace network/filesystem dependencies with stubs
• Remove non-deterministic ordering assumptions
• Fix incorrect framework usage (e.g. beforeAll when beforeEach is needed, missing await on async assertions, wrong matcher usage)