core-testing

name	core-testing
description	Apply Envilder testing conventions for Vitest unit tests and LocalStack e2e tests. Use when adding or updating tests for command handlers, domain entities, adapters, CLI, or GitHub Action flows.
argument-hint	feature or file under test

Envilder Testing Conventions

Outcome

Produce tests that match Envilder standards for naming, structure, and confidence level across unit, integration, and e2e coverage.

When To Use

• Adding tests for new application handlers or domain behavior
• Updating tests after refactors in CLI, GHA, infrastructure, or ports
• Reviewing whether test style is consistent before opening a PR

Inputs

• Target behavior, file, or feature to test
• Test level: unit, integration, or e2e
• Any error paths or edge conditions to validate

Procedure

1. Classify the test level and strategy.
   • Use unit tests by default for domain/application logic.
   • Use mocked port contracts (vi.fn()) for application handlers.
   • Use e2e tests only when real AWS SSM behavior must be validated.
2. Create test files in the matching test tree.
   • App and domain tests: tests/ mirrored to src/ structure.
   • E2E tests: e2e/ using LocalStack/TestContainers.
3. Name tests using the required pattern.
   • Should_<Expected>_When_<Condition>
   • Example: Should_ThrowError_When_SSMParameterIsNotFound
4. Write tests with explicit AAA sections.
   • Add comment markers in each test block:
     • // Arrange
     • // Act
     • // Assert
   • Each marker appears at most once per test. If you need to test two actions or two assertions on different behaviors, write two separate tests.
5. Mock at the port boundary for application tests.
   • Build test doubles by implementing domain port interfaces.
   • Prefer vi.fn() to control behavior and assertions.
6. Validate primary success and failure paths.
   • Success path (expected output/state change)
   • Domain error path (invalid input, missing parameter, etc.)
   • Empty/no-op behavior where relevant
7. Keep assertions behavior-focused.
   • Assert effects and interactions, not implementation details.
   • Verify calls to injected ports and logger where behavior requires it.
8. Run verification commands before completion.
   • pnpm test
   • pnpm lint
   • For CI parity when needed: pnpm test:ci

Decision Points

• If business rule is pure and deterministic: test at domain layer first.
• If orchestration calls multiple ports: test command handler with mocked dependencies.
• If AWS integration semantics are the risk: add or update e2e with LocalStack.
• Require e2e only when behavior changes cannot be proven confidently with unit tests.
• If only formatting/import changes occurred: update tests only when behavior changed or snapshots/assertions became stale.

Completion Criteria

• Test names follow Should_<Expected>_When_<Condition>
• AAA markers are present, clear, and appear at most once each per test
• Positive and negative paths are both covered
• No mandatory coverage percentage threshold is enforced by this skill
• Tests run green locally with pnpm test
• No type/lint regressions from test changes (pnpm lint)

Quick Prompt Examples

• "Use testing-conventions for PullSecretsToEnvCommandHandler and add missing error-path tests."
• "Apply testing-conventions to review tests/envilder/apps/gha/entry/Gha.test.ts for naming and AAA compliance."
• "Use testing-conventions to design e2e coverage for SSM not-found behavior."

Anti-Pattern: Duplicate Act/Assert Blocks

Wrong: two Acts and Asserts in one test:

it('Should_HandleParameters_When_Called', async () => {
  // Arrange
  const mockData = { KEY: '/ssm/path' };

  // Act
  await handler.handle(commandA);

  // Assert
  expect(mockStore.saveEnvironment).toHaveBeenCalledOnce();

  // Act
  await handler.handle(commandB);

  // Assert
  expect(mockStore.saveEnvironment).toHaveBeenCalledTimes(2);
});

Correct: split into two focused tests:

it('Should_SaveEnvironment_When_CommandAProvided', async () => {
  // Arrange
  const mockData = { KEY: '/ssm/path' };

  // Act
  await handler.handle(commandA);

  // Assert
  expect(mockStore.saveEnvironment).toHaveBeenCalledOnce();
});

it('Should_SaveEnvironment_When_CommandBProvided', async () => {
  // Arrange
  const mockData = { KEY: '/ssm/path' };

  // Act
  await handler.handle(commandB);

  // Assert
  expect(mockStore.saveEnvironment).toHaveBeenCalledOnce();
});