Android Macrobenchmark & Baseline Profiles 🏎️

App Startup Time and UI performance are crucial. Macrobenchmark allows us to write standard JUnit 4 tests to measure end-to-end user journeys (like app startup or scrolling a list) and automatically generate Baseline Profiles that Android's ART uses to pre-compile critical code.

⚡ When to Use

• When the prompt mentions "speeding up app startup time"
• When writing a Macrobenchmark module
• When generating or applying Baseline Profiles (baseline-prof.txt)

🏗️ Core Rules / Pillars

1. Separate Macrobenchmark Module

• Pattern: Macrobenchmarks MUST be in a separate com.android.test module. They launch your application by its applicationId externally.
• Anti-Pattern: Do NOT attempt to run Macrobenchmark tests inside the standard app/src/androidTest directory.

2. Writing a Scrolling Benchmark