picking-test-doubles

What problem does it solve?

It helps you choose the correct Android test double so your tests validate the right behavior without coupling to implementation details.

Core Features & Use Cases

• Decision matrix for Fake vs Mock vs Stub vs Spy vs Dummy vs Shadow: Covers when to use each double and explains the preference order for Android testing.
• State vs interaction guidance: Recommends fakes for state-bearing dependencies and mocks for verifying interactions; discourages spies unless refactoring is impractical.
• Robolectric Shadow support: Explains how shadows fit the taxonomy when you must substitute Android framework behavior (e.g., time via ShadowSystemClock).
• Concrete Android examples: Provides patterns for in-memory fakes (e.g., FakeUserRepository), interaction-focused mocks (e.g., verify / coVerify), and dummy placeholders.

Quick Start

Ask the AI to recommend whether you should use a fake, mock, stub, spy, dummy, or Robolectric shadow for your specific dependency based on what you’re trying to verify (state or interactions) and show the corresponding example test structure.