Best practices for writing JavaScript/TypeScript tests using Jest, including mocking strategies, test structure, and common patterns.
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.test.ts or .test.js suffix__tests__ directorydescribe('Component/Function/Class', () => { it('should do something', () => {}) })jest.mock() for module-level mocksjest.spyOn() for specific function mocksmockImplementation() or mockReturnValue() to define mock behaviorjest.resetAllMocks() in afterEachresolves/rejects matchers for promisesjest.setTimeout()userEvent over fireEvent for more realistic user interactionsexpect(value).toBe(expected), expect(value).toEqual(expected)expect(value).toBeTruthy(), expect(value).toBeFalsy()expect(value).toBeGreaterThan(3), expect(value).toBeLessThanOrEqual(3)expect(value).toMatch(/pattern/), expect(value).toContain('substring')expect(array).toContain(item), expect(array).toHaveLength(3)expect(object).toHaveProperty('key', value)expect(fn).toThrow(), expect(fn).toThrow(Error)expect(mockFn).toHaveBeenCalled(), expect(mockFn).toHaveBeenCalledWith(arg1, arg2)No reviews yet. Tell others what you thought.
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Primary accessibility skill for VS Code. REQUIRED for new feature and contribution work, and also applies to updates of existing UI. Covers accessibility help dialogs, accessible views, verbosity settings, signals, ARIA announcements, keyboard navigation, and ARIA labels/roles.
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Use this skill when the user explicitly asks to map, document, or onboard into an existing codebase. Trigger for prompts like "map this codebase", "document this architecture", "onboard me to this repo", or "create codebase docs". Do not trigger for routine feature implementation, bug fixes, or narrow code edits unless the user asks for repository-level discovery.
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Act on user feedback attached to the current session. Use when the user submits feedback on the session's changes via the Submit Feedback button.
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Add educational comments to the file specified, or prompt asking for file to comment if one is not provided.
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Use when adding, modifying, or reviewing VS Code configuration policies. Covers the full policy lifecycle from registration to export to platform-specific artifacts. Run on ANY change that adds a `policy:` field to a configuration property.
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Patterns and techniques for adding governance, safety, and trust controls to AI agent systems. Use this skill when: - Building AI agents that call external tools (APIs, databases, file systems) - Implementing policy-based access controls for agent tool usage - Adding semantic intent classification to detect dangerous prompts - Creating trust scoring systems for multi-agent workflows - Building audit trails for agent actions and decisions - Enforcing rate limits, content filters, or tool restrictions on agents - Working with any agent framework (PydanticAI, CrewAI, OpenAI Agents, LangChain, AutoGen)
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