test-conventions

name	test-conventions
description	Shared test conventions for all testing agents in the Lichtblick repo. Defines GWT pattern, core quality rules, and the standard test-writing workflow.

Test Conventions

Applies to all test agents (unit tests, E2E tests).

---

Given-When-Then (GWT)

Every test body must include GWT section comments.

Block-comment style (Desktop / E2E)

/**
 * GIVEN a .mcap file is loaded
 * WHEN play button is clicked
 * THEN playback time should advance
 */
test("should start playing when clicking on Play button", async ({ mainWindow }) => {
    // Given
    await loadFiles({ mainWindow, filenames: "example.mcap" });
    const button = mainWindow.getByTestId("play-button");

    // When
    await button.click();

    // Then
    await expect(button).toHaveAttribute("title", "Pause");
});

Inline comment style (Unit tests)

it("should return the layout when ID is valid", async () => {
    // Given
    const layout = LayoutBuilder.layout();
    // When
    const result = await service.findOne(layout.id);
    // Then
    expect(result).toEqual(layout);
});

---

Core Quality Rules

1. One logical assertion per test — split complex scenarios into separate test() / it() blocks.
2. Mock external dependencies, never business logic — mock file I/O, IPC, HTTP clients; test the real code under test.
3. Use existing builders and fixtures — never create raw test data inline when a builder or fixture exists.
4. Match sibling test structure exactly — same import style, same fixture usage, same GWT comment format as existing tests in the same directory.
5. Run tests after writing — execute to verify they pass before presenting results.
6. No any — use proper TypeScript types in all test code.
7. Always read before writing — read the source file AND at least one existing sibling test file before generating new tests.

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Test-Writing Workflow

1. Read the source file — understand the component or feature under test.
2. Read an existing sibling test — match the exact import style, fixture setup, and GWT comment format.
3. Identify available builders / fixtures — check testing/builders/ (unit), e2e/fixtures/ (E2E), and e2e/page-objects/ (E2E).
4. Write tests covering:
   • Happy path (valid input → expected outcome)
   • Edge cases (boundary values, empty state)
   • Error paths (invalid state → expected failure behavior)
5. Run the tests to confirm they pass.
6. Report which scenarios are covered and flag any missing edge cases.

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Test Naming

TypeScript (Unit tests — Jest)

• Describe blocks: describe('ComponentName') → describe('methodOrBehavior')
• Test titles: it('should <expected outcome> when <condition>')

TypeScript (E2E tests — Playwright)

• Top-level test() with a descriptive title: "should <expected outcome> when <condition>"
• Use a block-comment JSDoc above the test for the full GWT scenario description

---

Cleanup

Jest (unit tests)

afterEach(() => {
    jest.clearAllMocks();
    jest.restoreAllMocks();
});

Playwright (E2E)

• Each test gets an isolated app/page via fixtures — no manual cleanup needed between tests
• If a test opens a dialog or modifies shared state, restore it at the end of that test

---

Error Testing

Jest

await expect(service.create(dto)).rejects.toThrow(SomeException);

Playwright

await expect(page.getByRole("alert")).toBeVisible();
await expect(page.getByText("Error message")).toBeVisible();