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Testing & Quality Gates

Every PR runs format, lint, unit tests, Compose UI tests, screenshot regression tests, and an Android debug build via .github/workflows/pr_checks.yml. Run the same gates locally before pushing.

All commands run from MobileApp/.

Formatting & Lint — Spotless + ktlint​

Spotless drives ktlint across every module:

# Auto-fix every Kotlin source + Gradle KTS file:
./gradlew spotlessApply

# CI-style check (no edits, fails on violations):
./gradlew spotlessCheck

Rule overrides live in the root MobileApp/build.gradle.kts — Compose-friendly defaults disable rules that fight the framework (function-naming for @Composable PascalCase, no-wildcard-imports for the common androidx.compose.foundation.layout.* pattern, max-line-length).

Unit & Compose UI Tests​

Test source layout:

  • shared/src/commonTest/ — runs on both :shared:jvmTest and :shared:testAndroidHostTest. Use this for repository, use-case, and UiStateHolder tests.
  • shared/src/jvmTest/ — JVM-only. Use for headless Compose UI tests via runComposeUiTest (the multiplatform Compose test API).
  • shared/src/androidHostTest/ — Robolectric / Roborazzi screenshot tests + goldens (snapshots/).

Run:

./gradlew :shared:jvmTest :shared:testAndroidHostTest

Patterns​

Suspend / dispatcher tests — pass a StandardTestDispatcher tied to the runTest scheduler:

@Test
fun `executor returns success result`() = runTest {
    val executor = BackgroundExecutor(StandardTestDispatcher(testScheduler))
    val result = executor.execute { Result.success(42) }
    assertEquals(42, result.getOrNull())
}

StateFlow / UiStateHolder tests — collect emissions with kotlinx-coroutines-test (no Turbine needed). Override Dispatchers.Main so viewModelScope runs on a TestDispatcher:

@BeforeTest fun setUp() { Dispatchers.setMain(StandardTestDispatcher()) }
@AfterTest fun tearDown() { Dispatchers.resetMain() }

@Test
fun `incrementing emits initial then updated state`() = runTest {
    val holder = SampleCounterUiStateHolder()
    val emissions = mutableListOf<SampleCounterUiState>()
    val job = launch(UnconfinedTestDispatcher(testScheduler)) {
        holder.uiState.toList(emissions)
    }
    holder.onUiEvent(Increment); holder.onUiEvent(Increment)
    advanceUntilIdle()
    assertEquals(SampleCounterUiState(count = 2), emissions.last())
    job.cancel()
}

Compose UI tests — runComposeUiTest is the multiplatform Compose test API. Runs headlessly on JVM:

@OptIn(ExperimentalTestApi::class)
@Test
fun `clicking calls onClick`() = runComposeUiTest {
    var clicked = false
    setContent { ClickableLabel("Tap me", onClick = { clicked = true }) }
    onNodeWithText("Tap me").performClick()
    assertTrue(clicked)
}

Screenshot Regression Tests​

Powered by Roborazzi + ComposablePreviewScanner. Every @Preview under com.measify.kappmaker.* is automatically discovered, rendered via Robolectric, and snapshotted. You don't write a test class — just add a @Preview and re-run.

# Refresh goldens after a deliberate UI change:
./gradlew :shared:recordRoborazziAndroidHostTest

# Verify (CI step) — fails with diff PNGs if any preview drifts:
./gradlew :shared:verifyRoborazziAndroidHostTest

Goldens live under MobileApp/shared/src/androidHostTest/snapshots/ (commit them). On CI, failed runs upload diff PNGs as artifacts.

@Preview import — required​

Always use androidx.compose.ui.tooling.preview.Preview:

import androidx.compose.ui.tooling.preview.Preview

The deprecated org.jetbrains.compose.ui.tooling.preview.Preview is not discovered by ComposablePreviewScanner. The multiplatform-aware AndroidX import is provided by the org.jetbrains.compose.ui:ui-tooling-preview artifact (already wired in :shared and :designsystem).

Excluding flaky previews​

Inherently non-deterministic composables (animations driven by Random, time-based effects) need to opt out — either:

  • Drop @Preview from the flaky variant, OR
  • Make the randomness deterministic in LocalInspectionMode (e.g. inject a seeded Random when previewing).

The codebase has one example: ConfettiParticlesAnimatedPreview in the design system has @Preview removed because confetti positions are random per render.

Android Instrumented Tests​

Device-required UI tests still live under androidApp/src/androidTest/ and run with:

./gradlew :androidApp:connectedDebugAndroidTest

These don't run on PR checks — they need a connected device or emulator. Reserve them for tests that genuinely need the real Android runtime.