paparazzi VS dropshots

Component API tests are written for all components in the library. These are Paparazzi snapshot tests that are parameterized to cover all the combinations of values for the properties in the API of a given component. Additionally, they include as parameters: color theme, layout direction, and optionally other properties that may be relevant to the component under test (e.g., font scale).

Looks really nice. Sadly, I wasn't able to test it because it doesn't support application module

Curious what you mean by hilt refuses to work and what you have tried? Usually though if I'm testing the UI of the app, I might use paparazzi for screenshot tests because it doesn't have to run the test on device. Then for a UI integration test for navigation and user flows, use espresso and replace the network data sources with mocks which in your case would be with hilt android test rule and test install in annotation .

/** * Finds all files in the components module which have Compose previews * and generates Paparazzi screenshot tests for them. * * The generated tests can then be used to record screenshots with * ./gradlew components:recordPaparazziInternalDebug * * To verify that the current implementation matches the recorded screenshots * ./gradlew components:verifyPaparazziInternalDebug */ fun main() { val path = System.getProperty("user.dir") ?: error("Can't get user dir") // Paparazzi does not currently work in the app module: https://github.com/cashapp/paparazzi/issues/107 // For now this is hardcoded to only check files in the components module. // If we pull our compose files out of the app module to a separate module this code has to be updated. File(path).walk().filter { it.path.contains("/components/src/main/java") && it.extension == "kt" }.forEach { if (it.readText().contains("@Preview")) { processFileWithPreviews(it) } } } /** * Reads the given file, finds the names of all the functions annotated with @Preview * and uses them to generate a Paparazzi test file with one test for each preview. */ private fun processFileWithPreviews(file: File) { val lines = file.readLines() val previewNames = mutableListOf() var saveNextFunctionName = false var packageName = "" lines.forEachIndexed { i, line -> if (i == 0) { packageName = line.split(" ").last() } if (line.contains("@Preview")) { saveNextFunctionName = true } if (saveNextFunctionName && line.startsWith("fun ")) { previewNames += line.split(" ")[1].removeSuffix("()") saveNextFunctionName = false } } val pathString = file.path.replace("src/main", "src/test").split("java").first() + "java" val testFilePath = pathString.toPath() generatePaparazziTest(packageName, file.nameWithoutExtension + "PaparazziTest", testFilePath, previewNames) } fun generatePaparazziTest(packageName: String, fileName: String, path: Path, previewNames: List) { val classBuilder = TypeSpec.classBuilder(fileName) .superclass(PaparazziTest::class) .addAnnotation( AnnotationSpec.builder(Suppress::class) // KotlinPoet does not let us remove redundant public modifiers or Unit return types for the functions, // but we don't mind for generated code as long as the tests work .addMember("\"RedundantVisibilityModifier\", \"RedundantUnitReturnType\"") .build() ) previewNames.forEach { classBuilder.addFunction( FunSpec.builder(it.removeSuffix("Preview").usLocaleDecapitalize()) .addStatement("paparazziRule.snapshot { $it() }") .addAnnotation(Test::class) .build() ) } val testFile = FileSpec.builder(packageName, fileName) .addType(classBuilder.build()) .addFileComment("AUTO-GENERATED FILE by generate_paparazzi_tests.kt\nDO NOT MODIFY") .build() val nioPath = path.toNioPath() testFile.writeTo(nioPath) }

The good thing is, Square got us covered once more, in regards to the flaky emulators, by providing a screenshot-testing library that does not require an emulator: https://cashapp.github.io/paparazzi/

There's one major advantage to paparazzi though: it's way faster, which allows us to do the snapshot tests every commit instead of only nightly. Dropshots also seems promising, but still needs an emulator, so it won't be as fast as paparazzi.

Thanks. Yes, there is some similarities to Screenshot testing. Besides Paparazzi there are these other options if anyone is looking for that: http://shopify.github.io/android-testify/ https://github.com/dropbox/dropshots https://github.com/pedrovgs/Shot