Picking Test Doubles | Agent Skills Atlas

About this skill

Use this skill to pick the right test double — fake, mock, stub, spy, dummy, or Robolectric shadow — for an Android test. Encodes Google's verbatim preference order ("fakes ... are preferred", "Fakes are preferred over stubs for simplicity", "Fakes or mocks are therefore preferred over spies"), gives Android examples (in-memory FakeUserRepository, mockk (), ShadowSystemClock), and a decision matrix mapping intent to the correct double. Use when the user asks "fake or mock", "should I use Mockito here", "how do I replace this dependency in tests", "what's the difference between a stub and a mock", "spy vs mock", or mentions mockk, every { } returns, verify { }, org.mockito, argumentCaptor, Robolectric shadows, ShadowSystemClock, or FakeRepository.

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0 potential findings · Scanned 11/4/2026 · Scanner 0.2.1

Content SHA-256: 537b057ed4ff4c4c53efbe05ed413e493c5dafd33e3e82d81e61504172b1add2

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Original listing metadata

Original name

picking-test-doubles

Original description

Use this skill to pick the right test double — fake, mock, stub, spy, dummy, or Robolectric shadow — for an Android test. Encodes Google's verbatim preference order ("fakes ... are preferred", "Fakes are preferred over stubs for simplicity", "Fakes or mocks are therefore preferred over spies"), gives Android examples (in-memory `FakeUserRepository`, `mockk<UserRepository>()`, `ShadowSystemClock`), and a decision matrix mapping intent to the correct double. Use when the user asks "fake or mock", "should I use Mockito here", "how do I replace this dependency in tests", "what's the difference between a stub and a mock", "spy vs mock", or mentions `mockk`, `every { } returns`, `verify { }`, `org.mockito`, `argumentCaptor`, `Robolectric` shadows, `ShadowSystemClock`, or `FakeRepository`.

About this listing

Category: Engineering
Reported license: Apache-2.0
Listing language (estimated): English
Review status: Not individually reviewed
Agent compatibility: Atlas installation supports Claude Code, Codex, and Cursor. Skill-specific dependencies and features are checked during setup.