Test pyramid and strategy

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Test Pyramid And Strategy Deep Dive

Overview

The pyramid is a cost model: many cheap tests, fewer expensive ones.

Core Concepts

• Unit tests validate decision logic.
• Integration tests validate contracts.
• UI/E2E validate key user outcomes.

Test Pyramid and Strategy

• Keep the base broad and stable.
• Avoid over-investing in brittle UI tests.
• Use risk-based prioritization for top flows.

Tooling and Infrastructure

• Distinct test modules and clear ownership.
• Stable test data builders and fixtures.

Flaky Test Mitigation

• No sleeps; use explicit synchronization.
• Disable network/time nondeterminism.

Code Examples

@Test
fun useCase_emitsError_whenDependencyFails() {
    // deterministic dependency behavior
}

Common Interview Questions

• Q: Is the pyramid still relevant with Compose? A: Explain runtime behavior: what invalidates state, how recomposition is scoped, where side effects live, and how to verify frame stability with profiler traces.
• Q: How do you justify fewer E2E tests? A: Answer by test pyramid intent: unit for logic speed, integration for boundaries, and end-to-end for critical journeys with flakiness controls.

Production Considerations

• Tie strategy to release risk and incident history.

Performance Insights

• A healthy pyramid keeps CI fast as the codebase grows.

Senior-Level Insights

• Staff-level candidates explain organizational tradeoffs, not just tooling.