Test Analysis Extensions

TypeScript / JavaScript Test Frameworks Reference (Jest, Vitest, Mocha, Jasmine, node:test)

Reference data for analyzing JS/TS test code. Used by the polyglot test analysis skills.

Capability tags

Test File Identification

Assertion APIs

Third-party libraries: chai, should, sinon-chai, @vitest/expect.

Sleep/Delay Patterns

Skip/Ignore Annotations

.only patterns are an anti-pattern when committed — they silently disable the rest of the suite.

Exception Handling — Idiomatic Alternatives

// Jest / Vitest (sync):
expect(() => parseAmount(-5)).toThrow(RangeError);

// Jest / Vitest (async):
await expect(parseAmountAsync(-5)).rejects.toThrow(RangeError);

// Chai:
expect(() => parseAmount(-5)).to.throw(RangeError, /must be positive/);

// node:test:
assert.throws(() => parseAmount(-5), RangeError);
await assert.rejects(parseAmountAsync(-5), RangeError);

Flag try { ... } catch (e) { /* nothing */ } and try { ... } catch { expect(...) } patterns as Exception Handling smells unless the catch performs a specific assertion.

Mystery Guest — Common JS/TS Patterns

Integration Test Markers

• Folder names: __tests__/integration/, tests/e2e/, cypress/, playwright/

• File suffix: *.integration.test.ts, *.e2e.test.ts

• describe('Integration: …', …) wrappers

• Playwright/Cypress/WebdriverIO usage almost always implies E2E

Setup/Teardown

Tag/Trait Attributes (for test-tagging)

Default mode: report-only. JS/TS test frameworks generally have no canonical tag attribute. Strategies:

• describe-based grouping — wrap tests in describe('@positive | OrderService', ...) and grep the prefix.

• Test name prefixes — it('[boundary] handles zero quantity', ...).

• Vitest options object — Vitest accepts arbitrary metadata on tests but no first-class tag filter.

• Custom reporters — projects can read JSDoc-style @tags and surface them.

Only switch to auto-edit mode when the project already follows one of these conventions (detect by sampling existing tests).

Language-specific calibration notes

• Async tests missing await are a critical smell. expect(promise).resolves.toBe(...) without await resolves nothing and the test passes silently. Flag any unawaited promise inside a test body (linters: @typescript-eslint/no-floating-promises, vitest/no-disabled-tests).

• Snapshot tests count as assertions — but flag stale or always-passing snapshots (no expect.assertions(n) and only toMatchSnapshot).

• expect.assertions(n) is a useful guardrail; tests using it lock in assertion count.

• Implicit assertion via mock matchers: expect(mock).toHaveBeenCalled() is a valid assertion — do not treat as assertion-free.

• Done callbacks in Mocha-style tests (it('x', (done) => { ... done(); })) are legacy; absence of done() call in a callback test is a silent pass.

• xit/xdescribe are commits of disabled tests — flag like [Ignore].

• .only committed to source is a critical smell — silently disables the rest of the file/suite.

• describe.each / test.each are parametrized; not duplicate tests.

• fail() is removed in Jest 27+ — flag if (cond) fail('msg') patterns and recommend throw new Error('msg') or an explicit failing assertion such as expect(value).toBe(...) instead.