Agent skill

Android Coroutine Testing

Comprehensive guidance for writing deterministic tests for Android code using Kotlin coroutines.

Apache-2.0Auto-check passedMobile

Install Android Coroutine Testing

skills CLI

$ npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install timusus/Shuttle2 android-coroutine-testing --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/timusus/Shuttle2.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/android-coroutine-testing .claude/skills/android-coroutine-testing && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "android-coroutine-testing" agent skill from https://github.com/timusus/Shuttle2/tree/main/.claude/skills/android-coroutine-testing into .claude/skills/android-coroutine-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "android-coroutine-testing", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/timusus/Shuttle2/tree/main/.claude/skills/android-coroutine-testing

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install timusus/Shuttle2 android-coroutine-testing --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/timusus/Shuttle2.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/skills/android-coroutine-testing .agents/skills/android-coroutine-testing && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "android-coroutine-testing" agent skill from https://github.com/timusus/Shuttle2/tree/main/.claude/skills/android-coroutine-testing into .agents/skills/android-coroutine-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "android-coroutine-testing", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install timusus/Shuttle2 android-coroutine-testing --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/timusus/Shuttle2.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/skills/android-coroutine-testing .cursor/skills/android-coroutine-testing && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "android-coroutine-testing" agent skill from https://github.com/timusus/Shuttle2/tree/main/.claude/skills/android-coroutine-testing into .cursor/skills/android-coroutine-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "android-coroutine-testing", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/timusus/Shuttle2.git --path .claude/skills/android-coroutine-testing

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install timusus/Shuttle2 android-coroutine-testing --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/timusus/Shuttle2.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/skills/android-coroutine-testing .gemini/skills/android-coroutine-testing && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "android-coroutine-testing" agent skill from https://github.com/timusus/Shuttle2/tree/main/.claude/skills/android-coroutine-testing into .gemini/skills/android-coroutine-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "android-coroutine-testing", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install timusus/Shuttle2 android-coroutine-testing

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/timusus/Shuttle2.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/skills/android-coroutine-testing .github/skills/android-coroutine-testing && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "android-coroutine-testing" agent skill from https://github.com/timusus/Shuttle2/tree/main/.claude/skills/android-coroutine-testing into .github/skills/android-coroutine-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "android-coroutine-testing", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install timusus/Shuttle2 android-coroutine-testing --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/timusus/Shuttle2.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/skills/android-coroutine-testing .opencode/skills/android-coroutine-testing && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "android-coroutine-testing" agent skill from https://github.com/timusus/Shuttle2/tree/main/.claude/skills/android-coroutine-testing into .opencode/skills/android-coroutine-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "android-coroutine-testing", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: android-coroutine-testing
GitHub stars: 229
Token cost: ~1.2k tokens
SKILL.md length: 325 words
Files: 1
Skills in repo: 13
Repo updated: Oct 7, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

Comprehensive guidance for writing deterministic tests for Android code using Kotlin coroutines.

Works in 5 steps: One scheduler per test - Share scheduler… → Inject dispatchers - Never use… → Use runTest - One invocation per test… → …
Testing suspending functions
SKILL.md covers Quick Start, Key Concepts, Working with Scopes and Time Control, plus 4 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Android Coroutine Testing is an agent skill from timusus/Shuttle2. Comprehensive guidance for writing deterministic tests for Android code using Kotlin coroutines. Use when testing suspending functions, coroutines, flows, ViewModels with coroutines, or when needing to handle test dispatchers, runTest, backgroundScope, testScope, or virtual time control.

Its SKILL.md is about 1.2k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Mobile. It works with Android and Kotlin. The repository describes itself as: Shuttle Music: a music player for Android and iOS. Plays local files and streams from Jellyfin, Emby, Plex and Navidrome/Subsonic, with Chromecast, Android Auto, EQ and replay… The licence is Apache-2.0.

When your agent uses it

Testing suspending functions
ViewModels with coroutines
Needing to handle test dispatchers
BackgroundScope

Example prompts

“/android-coroutine-testing”

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

One scheduler per test - Share scheduler between all test dispatchers
Inject dispatchers - Never use Dispatchers.IO or Dispatchers.Default directly
Use runTest - One invocation per test method
Clean up flows - Cancel infinite flow collections
Avoid real delays - Use virtual time instead

What it can do on your machine

Read from SKILL.md and the folder at commit 9cef5dd. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are kotlin).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Android Coroutine Testing loads about 1.2k tokens when it runs. Until then it costs about 79 tokens; SKILL.md has 325 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~79
When it runs · the whole SKILL.md, loaded when a task matches: ~1.2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from timusus/Shuttle2 at commit 9cef5dd, republished under its Apache-2.0 licence (© timusus). 325 words, ~1,165 tokens.

Download SKILL.mdSave it as .claude/skills/android-coroutine-testing/SKILL.md (or your agent's skills folder).

name: android-coroutine-testing
description: Comprehensive guidance for writing deterministic tests for Android code using Kotlin coroutines. Use when testing suspending functions, coroutines, flows, ViewModels with coroutines, or when needing to handle test dispatchers, runTest, backgroundScope, testScope, or virtual time control.

Android Coroutine Testing

Write deterministic tests for coroutine-based Android code using runTest, test dispatchers, and proper scope management.

Quick Start

Basic Setup

The kotlinx-coroutines-test dependency (version 1.10.2, see gradle/libs.versions.toml) is already on the test classpath via libs.kotlinx.coroutinesTest.

Essential Testing Pattern

kotlin

@Test
fun myCoroutineTest() = runTest {
    // Arrange
    val testDispatcher = StandardTestDispatcher(testScheduler)
    val repository = MyRepository(testDispatcher)

    // Act
    val result = repository.fetchData()

    // Assert
    assertEquals("expected", result)
}

Key Concepts

runTest

Wraps test code that calls suspending functions
Automatically skips delays (uses virtual time)
Waits for coroutines on test dispatchers to complete
Use expression body syntax: = runTest { ... }

Test Dispatchers

StandardTestDispatcher (default)

Queues new coroutines
Requires manual time advancement
Use advanceUntilIdle() to run pending work
Best for testing precise execution order

UnconfinedTestDispatcher

Executes coroutines eagerly/immediately
Simpler tests but different from production behavior
Use when execution order doesn't matter

Dispatcher Injection

Always inject dispatchers for testability:

kotlin

// Bad - Hardcoded dispatcher
class Repository {
    suspend fun fetchData() = withContext(Dispatchers.IO) { ... }
}

// Good - Injectable dispatcher
class Repository(
    private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) {
    suspend fun fetchData() = withContext(ioDispatcher) { ... }
}

Main Dispatcher

Replace the Main dispatcher using the repo's existing rule at android/app/src/test/java/com/simplecityapps/testing/MainDispatcherRule.kt:

kotlin

@get:Rule
val mainDispatcherRule = MainDispatcherRule()

@Test
fun viewModelTest() = runTest {
    val viewModel = MyViewModel()
    viewModel.loadData() // Uses test Main dispatcher
    assertEquals(expected, viewModel.state.value)
}

It defaults to UnconfinedTestDispatcher; pass a StandardTestDispatcher(testScheduler) if a test needs precise execution order instead.

Working with Scopes

TestScope Usage

kotlin

@Test
fun testWithBackgroundWork() = runTest {
    // Use backgroundScope for work that outlives the test body
    backgroundScope.launch {
        // Long-running collection
        repository.dataFlow.collect { ... }
    }

    // Test body completes, but waits for backgroundScope
    repository.updateData("new")
    advanceUntilIdle()
}

Injecting Scopes

kotlin

class MyClass(private val scope: CoroutineScope) {
    fun startWork() {
        scope.launch { ... }
    }
}

@Test
fun scopeInjectionTest() = runTest {
    val myClass = MyClass(scope = this) // Pass TestScope
    myClass.startWork()
    advanceUntilIdle()
}

Time Control

Control virtual time in tests:

advanceUntilIdle() - Run all pending coroutines
advanceTimeBy(millis) - Advance time and run scheduled work
runCurrent() - Run coroutines at current time only
testScheduler.currentTime - Check current virtual time

Exception Handling

kotlinx-coroutines-test surfaces uncaught exceptions from backgroundScope and other test dispatchers by failing the runTest block directly — no separate exception-handler utility is needed. Assert with a standard assertThrows / try/catch around the failing call instead.

Best Practices

One scheduler per test - Share scheduler between all test dispatchers
Inject dispatchers - Never use Dispatchers.IO or Dispatchers.Default directly
Use runTest - One invocation per test method
Clean up flows - Cancel infinite flow collections
Avoid real delays - Use virtual time instead

Flow Testing

This repo does not depend on Turbine. Test Flow emissions by collecting into a list inside runTest (e.g. via backgroundScope.launch { flow.toList(results) } or flow.first()/flow.take(n).toList()) and asserting on the collected values.

Mocking

MockK (libs.mockk) is on the test classpath if a mock is genuinely needed. Prefer a real fake implementation over a mock where the collaborator is simple (e.g. an in-memory repository).

Files

Just SKILL.md in .claude/skills/android-coroutine-testing of timusus/Shuttle2.

Open the folder on GitHubat commit 9cef5dd

Compare with similar skills

Android Coroutine Testing next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Android Coroutine Testing compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Android Coroutine Testing this skilltimusus/Shuttle2	229	—	~1.2k	Automated safety check: Pass	Apache-2.0	yesterday
Android Hidden API and R8 Checkgkd-kit/gkd	43k	—	~1.5k	Automated safety check: Pass	GPL-3.0	yesterday
Compose Multiplatform Patternsmonta-app/ocpp-emulator	180	5 repos	~2k	Automated safety check: Pass	Apache-2.0	7 days ago
Android Developmentdpconde/claude-android-skill	336	—	~1.7k	Automated safety check: Pass	MIT	10 mo ago
Ha Android Architecturehome-assistant/android	4k	—	~1.7k	Automated safety check: Pass	Apache-2.0	yesterday
Architecture Overclocknekomangaorg/Neko	2.8k	—	~1.4k	Automated safety check: Pass	Apache-2.0	yesterday

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Questions about Android Coroutine Testing

What does Android Coroutine Testing do?

Comprehensive guidance for writing deterministic tests for Android code using Kotlin coroutines. Android Coroutine Testing is an agent skill from timusus/Shuttle2. Comprehensive guidance for writing deterministic tests for Android code using Kotlin coroutines.

When should I use Android Coroutine Testing?

Android Coroutine Testing fits situations like: testing suspending functions; viewModels with coroutines; needing to handle test dispatchers; backgroundScope.

How do I install Android Coroutine Testing in Claude Code?

Run `npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a claude-code`. Or copy the skill folder (.claude/skills/android-coroutine-testing in timusus/Shuttle2) into .claude/skills/android-coroutine-testing in your project. Claude Code loads it when a task matches its description.

How do I install Android Coroutine Testing in Codex?

Run `npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a codex`. Or copy the skill folder (.claude/skills/android-coroutine-testing in timusus/Shuttle2) into .agents/skills/android-coroutine-testing in your project. Codex loads it when a task matches its description.

Can I use Android Coroutine Testing in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add timusus/Shuttle2 --skill android-coroutine-testing -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/android-coroutine-testing, .gemini/skills/android-coroutine-testing, .github/skills/android-coroutine-testing and .opencode/skills/android-coroutine-testing in your project.

What does Android Coroutine Testing need to run?

SKILL.md names no scripts, command-line tools or credentials: Android Coroutine Testing is instructions for the agent only.

Does Android Coroutine Testing access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Android Coroutine Testing safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Android Coroutine Testing use?

Android Coroutine Testing is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Android Coroutine Testing use?

About 1.2k tokens (SKILL.md is roughly 4.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Android Coroutine Testing?

Skills that share tags, products or a category with Android Coroutine Testing: Android Hidden API and R8 Check (gkd-kit/gkd, 43k stars), Compose Multiplatform Patterns (monta-app/ocpp-emulator, 180 stars), Android Development (dpconde/claude-android-skill, 336 stars) and Ha Android Architecture (home-assistant/android, 4k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Android Coroutine Testing?

timusus (a GitHub user) maintains it in timusus/Shuttle2, which has 229 GitHub stars. The repository holds 13 skills in this directory. The repository was last updated on October 7, 2026.

Source: timusus/Shuttle2 on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Android Coroutine Testing

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Android Coroutine Testing

Quick Start

Basic Setup

Essential Testing Pattern

Key Concepts

runTest

Test Dispatchers

Dispatcher Injection

Main Dispatcher

Working with Scopes

TestScope Usage

Injecting Scopes

Time Control

Exception Handling

Best Practices

Flow Testing

Mocking

Files

Compare with similar skills

Similar skills

More from timusus/Shuttle2

Related

Questions about Android Coroutine Testing