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setting-up-host-vs-device-tests

Select host or device source sets for Jetpack Compose UI tests.

303|10|Updated May 15, 2026
Search Tags:#jetpack compose#screenshot tests#androidTest#robolectric#instrumentation tests#androidHostTest#render thread
One-click install
npx skills add https://github.com/skydoves/android-testing-skills --skill setting-up-host-vs-device-tests
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: setting-up-host-vs-device-tests
Source: https://github.com/skydoves/android-testing-skills/tree/main/compose/setup/setting-up-host-vs-device-tests
Command: npx skills add https://github.com/skydoves/android-testing-skills --skill setting-up-host-vs-device-tests

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

It helps you decide whether a Jetpack Compose test should run on the host (Robolectric/JVM) or on a real/virtual device (instrumentation), and then configure it so key capabilities actually work.

Core Features & Use Cases

  • Host vs device selection: Use src/test/ (host) for fast logic/recomposition/finder-style assertions, and src/androidTest/ (device) for RenderThread-dependent behavior.
  • Correct source-set placement: Organize tests so screenshot capture, ripple/Modifier.indication rendering, and accessibility checks run in the right flavor.
  • Robolectric host skeleton & guardrails: Apply the canonical @RunWith(AndroidJUnit4::class) and @Config(minSdk = 23) setup and enforce clock-driven determinism.
  • Legitimate Thread.sleep only for RenderThread: Replace Thread.sleep in host tests entirely, and allow it in device tests only as a RenderThread waiting mechanism for screenshot/golden assertions.

Quick Start

Tell the AI: “I have a Jetpack Compose test that passes locally but fails on CI—should it go in src/test or src/androidTest, and what setup do I need?”

Frequently Asked Questions about setting-up-host-vs-device-tests

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I choose between Robolectric and instrumentation tests for Jetpack Compose?▼

Use src/test (host) with Robolectric for fast logic and finder-style assertions, and src/androidTest (device) for RenderThread-dependent behaviors like screenshots, ripples, and accessibility checks.

Why does my Compose screenshot test fail when using Robolectric?▼

Compose screenshot tests fail under Robolectric if placed in the wrong source set or lacking @Config(minSdk = 23). Move RenderThread-dependent screenshot and ripple rendering to androidTest.

What is the correct way to handle timing in Jetpack Compose UI tests?▼

Drive deterministic Compose UI test timing using mainClock.advanceTimeBy. Restrict Thread.sleep exclusively to device tests for waiting on the RenderThread during screenshot or ripple assertions.

Can I use Thread.sleep in Compose host tests for animations?▼

No, replace Thread.sleep entirely in host tests with mainClock.advanceTimeBy for deterministic animation and gesture timing. Only use Thread.sleep in device tests for RenderThread-dependent screenshot waiting.

Do I need @Config for Jetpack Compose Robolectric tests?▼

Yes, canonical Compose Robolectric tests require the @RunWith(AndroidJUnit4::class) and @Config(minSdk = 23) setup to enforce proper execution environments and clock-driven determinism.

When should Compose accessibility checks run on device versus host?▼

Compose accessibility checks should run in the src/androidTest device source set alongside other RenderThread-dependent behaviors like indication rendering and screenshot capture.

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