Implemented Showkase + Paparazzi artifact to automate screenshot testing

build.gradle

@@ -13,7 +13,7 @@ buildscript {
  'detekt' : '1.7.4',
  'espresso' : '3.2.0',
  'gradle' : '7.2.1',
- 'junit' : '4.13',
+ 'junit' : '4.13.2',
  'junitImplementation' : '1.1.2',
  'kotlin' : '1.7.10',
  'kotlinCompilerVersion' : '1.7.0',
@@ -23,6 +23,7 @@ buildscript {
  'ksp' : "$KSP_VERSION",
  'ktx' : '1.1.0',
  'lifecycle' : '2.2.0',
+ 'paparazzi' : '1.1.0',
  'picasso' : '2.8',
  'appcompat' : '1.4.0',
  'testRunner' : '1.4.0',
@@ -77,7 +78,8 @@ buildscript {
  'androidxTestRunner' : "androidx.test:runner:${versions.testRunner}",
  'strikt' : "io.strikt:strikt-core:${versions.strikt}",
  'shotAndroid' : "com.karumi:shot-android:${versions.shot}",
- 'testParameterInjector': "com.google.testparameterinjector:test-parameter-injector:${versions.testParameterInjector}"
+ 'testParameterInjector': "com.google.testparameterinjector:test-parameter-injector:${versions.testParameterInjector}",
+ 'paparazzi' : "app.cash.paparazzi:paparazzi:${versions.paparazzi}"
  ],
  'material' : [
  'material' : "com.google.android.material:material:${versions.material}",

settings.gradle

@@ -10,3 +10,4 @@ include ':showkase-browser-testing'
 include ':showkase-browser-testing-submodule'
 include ':showkase-screenshot-testing-shot'
 include ':showkase-screenshot-testing-paparazzi-sample'
+include ':showkase-screenshot-testing-paparazzi'

showkase-processor-testing/src/test/java/com/airbnb/android/showkase_processor_testing/ShowkaseProcessorTest.kt

@@ -202,7 +202,7 @@ class ShowkaseProcessorTest : BaseProcessorTest() {
  @Test
  fun `open class with no interface but ShowkaseScreenshoTest annotation throws compilation error`() {
  assertCompilationFails(
- "Only an implementation of com.airbnb.android.showkase.screenshot.testing.ShowkaseScreenshotTest can be annotated with @ShowkaseScreenshot"
+ "Only an implementation of com.airbnb.android.showkase.screenshot.testing.ShowkaseScreenshotTest or com.airbnb.android.showkase.screenshot.testing.paparazzi.PaparazziShowkaseScreenshotTest can be annotated with @ShowkaseScreenshot"
  )
  }
 

showkase-processor/src/main/java/com/airbnb/android/showkase/processor/ShowkaseProcessor.kt

@@ -22,6 +22,7 @@ import com.airbnb.android.showkase.processor.models.getShowkaseColorMetadata
 import com.airbnb.android.showkase.processor.models.getShowkaseMetadata
 import com.airbnb.android.showkase.processor.models.getShowkaseMetadataFromPreview
 import com.airbnb.android.showkase.processor.models.getShowkaseTypographyMetadata
+import com.airbnb.android.showkase.processor.writer.PaparazziShowkaseScreenshotTestWriter
 import com.airbnb.android.showkase.processor.writer.ShowkaseBrowserProperties
 import com.airbnb.android.showkase.processor.writer.ShowkaseBrowserWriter
 import com.airbnb.android.showkase.processor.writer.ShowkaseBrowserWriter.Companion.CODEGEN_AUTOGEN_CLASS_NAME
@@ -212,7 +213,7 @@ class ShowkaseProcessor @JvmOverloads constructor(
  val rootElement = getShowkaseRootElement(roundEnvironment, environment)
 
  // Showkase test annotation
- val screenshotTestElement = getShowkaseScreenshotTestElement(roundEnvironment)
+ val (screenshotTestElement, screenshotTestType) = getShowkaseScreenshotTestElement(roundEnvironment)
 
  var showkaseBrowserProperties = ShowkaseBrowserProperties()
 
@@ -231,9 +232,10 @@ class ShowkaseProcessor @JvmOverloads constructor(
  )
  }
 
- if (screenshotTestElement != null) {
+ if (screenshotTestElement != null && screenshotTestType != null) {
  // Generate screenshot test file if ShowkaseScreenshotTest is present in the root module
- writeScreenshotTestFiles(screenshotTestElement, rootElement, showkaseBrowserProperties)
+ writeScreenshotTestFiles(screenshotTestElement, screenshotTestType, rootElement,
+ showkaseBrowserProperties)
  }
  }
 
@@ -246,11 +248,13 @@ class ShowkaseProcessor @JvmOverloads constructor(
  return showkaseRootElements.singleOrNull() as XTypeElement?
  }
 
- private fun getShowkaseScreenshotTestElement(roundEnvironment: XRoundEnv): XTypeElement? {
+ private fun getShowkaseScreenshotTestElement(
+ roundEnvironment: XRoundEnv
+ ): Pair<XTypeElement?, ScreenshotTestType?> {
  val testElements = roundEnvironment.getElementsAnnotatedWith(ShowkaseScreenshot::class)
  .filterIsInstance<XTypeElement>()
- showkaseValidator.validateShowkaseTestElement(testElements, environment)
- return testElements.singleOrNull()
+ val screenshotTestType = showkaseValidator.validateShowkaseTestElement(testElements, environment)
+ return testElements.singleOrNull() to screenshotTestType
  }
 
  private fun writeShowkaseFiles(
@@ -288,6 +292,7 @@ class ShowkaseProcessor @JvmOverloads constructor(
 
  private fun writeScreenshotTestFiles(
  screenshotTestElement: XTypeElement,
+ screenshotTestType: ScreenshotTestType,
  rootElement: XTypeElement?,
  showkaseBrowserProperties: ShowkaseBrowserProperties,
  ) {
@@ -329,11 +334,7 @@ class ShowkaseProcessor @JvmOverloads constructor(
  }
 
  writeShowkaseScreenshotTestFile(
- // We only handle composables without preview parameter for screenshots. This is because
- // there's no way to get information about how many previews are dynamically generated using
- // preview parameter as it happens on run time and our codegen doesn't get enough information
- // to be able to predict how many extra composables the preview parameters extrapolate to.
- // TODO(vinaygaba): Add screenshot testing support for composabable with preview parameters as well
+ screenshotTestType,
  showkaseTestMetadata.componentsSize,
  showkaseTestMetadata.colorsSize,
  showkaseTestMetadata.typographySize,
@@ -434,22 +435,42 @@ class ShowkaseProcessor @JvmOverloads constructor(
 
  @Suppress("LongParameterList")
  private fun writeShowkaseScreenshotTestFile(
+ screenshotTestType: ScreenshotTestType,
  componentsSize: Int,
  colorsSize: Int,
  typographySize: Int,
  screenshotTestPackageName: String,
  rootModulePackageName: String,
  testClassName: String,
  ) {
- ShowkaseScreenshotTestWriter(environment).apply {
- generateScreenshotTests(
- componentsSize,
- colorsSize,
- typographySize,
- screenshotTestPackageName,
- rootModulePackageName,
- testClassName
- )
+ when(screenshotTestType) {
+ // We only handle composables without preview parameter for screenshots. This is because
+ // there's no way to get information about how many previews are dynamically generated using
+ // preview parameter as it happens on run time and our codegen doesn't get enough information
+ // to be able to predict how many extra composables the preview parameters extrapolate to.
+ // TODO(vinaygaba): Add screenshot testing support for composabable with preview
+ // parameters as well
+ ScreenshotTestType.SHOWKASE -> {
+ ShowkaseScreenshotTestWriter(environment).apply {
+ generateScreenshotTests(
+ componentsSize,
+ colorsSize,
+ typographySize,
+ screenshotTestPackageName,
+ rootModulePackageName,
+ testClassName
+ )
+ }
+ }
+ ScreenshotTestType.PAPARAZZI_SHOWKASE -> {
+ PaparazziShowkaseScreenshotTestWriter(environment).apply {
+ generateScreenshotTests(
+ screenshotTestPackageName,
+ rootModulePackageName,
+ testClassName
+ )
+ }
+ }
  }
  }
 
@@ -459,15 +480,12 @@ class ShowkaseProcessor @JvmOverloads constructor(
  val typographySize: Int,
  )
  companion object {
- const val COMPOSABLE_CLASS_NAME = "androidx.compose.runtime.Composable"
- const val COMPOSABLE_SIMPLE_NAME = "Composable"
- const val PREVIEW_CLASS_NAME = "androidx.compose.ui.tooling.preview.Preview"
- const val PREVIEW_SIMPLE_NAME = "Preview"
- const val PREVIEW_PARAMETER_CLASS_NAME =
- "androidx.compose.ui.tooling.preview.PreviewParameter"
- const val PREVIEW_PARAMETER_SIMPLE_NAME = "PreviewParameter"
- const val TYPE_STYLE_CLASS_NAME = "androidx.compose.ui.text.TextStyle"
- const val CODEGEN_PACKAGE_NAME = "com.airbnb.android.showkase"
+ internal const val COMPOSABLE_SIMPLE_NAME = "Composable"
+ internal const val PREVIEW_CLASS_NAME = "androidx.compose.ui.tooling.preview.Preview"
+ internal const val PREVIEW_SIMPLE_NAME = "Preview"
+ internal const val PREVIEW_PARAMETER_SIMPLE_NAME = "PreviewParameter"
+ internal const val TYPE_STYLE_CLASS_NAME = "androidx.compose.ui.text.TextStyle"
+ internal const val CODEGEN_PACKAGE_NAME = "com.airbnb.android.showkase"
  }
 }
 
@@ -489,3 +507,8 @@ internal enum class ShowkaseGeneratedMetadataType {
  TYPOGRAPHY
 }
 
+internal enum class ScreenshotTestType {
+ SHOWKASE,
+ PAPARAZZI_SHOWKASE
+}
+

showkase-processor/src/main/java/com/airbnb/android/showkase/processor/logging/ShowkaseValidator.kt

@@ -15,6 +15,7 @@ import com.airbnb.android.showkase.annotation.ShowkaseComposable
 import com.airbnb.android.showkase.annotation.ShowkaseRoot
 import com.airbnb.android.showkase.annotation.ShowkaseRootModule
 import com.airbnb.android.showkase.annotation.ShowkaseScreenshot
+import com.airbnb.android.showkase.processor.ScreenshotTestType
 import com.airbnb.android.showkase.processor.ShowkaseProcessor.Companion.COMPOSABLE_SIMPLE_NAME
 import com.airbnb.android.showkase.processor.ShowkaseProcessor.Companion.PREVIEW_PARAMETER_SIMPLE_NAME
 import com.airbnb.android.showkase.processor.exceptions.ShowkaseProcessorException
@@ -306,8 +307,8 @@ internal class ShowkaseValidator {
  internal fun validateShowkaseTestElement(
  elements: Collection<XTypeElement>,
  environment: XProcessingEnv,
- ) {
- if (elements.isEmpty()) return
+ ): ScreenshotTestType? {
+ if (elements.isEmpty()) return null
 
  val showkaseScreenshotAnnotationName = ShowkaseScreenshot::class.java.simpleName
 
@@ -330,18 +331,68 @@ internal class ShowkaseValidator {
 
  // Validate that the class annotated with @ShowkaseScreenshot extends the
  // ShowkaseScreenshotTest interface
- requireInterface(
- element = element,
- interfaceType = showkaseScreenshotTestTypeMirror,
- annotationName = showkaseScreenshotAnnotationName,
- )
+ val isShowkaseScreenshotTest =
+ showkaseScreenshotTestTypeMirror.isAssignableFrom(element.type)
+
+ return if (isShowkaseScreenshotTest) {
+ ScreenshotTestType.SHOWKASE
+ } else if (
+ environment.findType(PAPARAZZI_SHOWKASE_SCREENSHOT_TEST_CLASS_NAME)
+ ?.isAssignableFrom(element.type) == true
+ ) {
+ val paparazziShowkaseScreenshotTestTypeMirror = environment
+ .requireType(PAPARAZZI_SHOWKASE_SCREENSHOT_TEST_CLASS_NAME)
+ validatePaparazziShowkaseScreenshotTest(environment, element,
+ paparazziShowkaseScreenshotTestTypeMirror)
+
+ ScreenshotTestType.PAPARAZZI_SHOWKASE
+ } else {
+ throw ShowkaseProcessorException(
+ "Only an implementation of com.airbnb.android.showkase.screenshot.testing" +
+ ".ShowkaseScreenshotTest or com.airbnb.android.showkase.screenshot" +
+ ".testing.paparazzi.PaparazziShowkaseScreenshotTest can be annotated " +
+ "with @$showkaseScreenshotAnnotationName",
+ element
+ )
+ }
 
  // TODO(vinaygaba): Validate that the passed root class is annotated with @ShowkaseRoot
  // and implements [ShowkaseRootModule]
  }
  }
  }
 
+ private fun validatePaparazziShowkaseScreenshotTest(
+ environment: XProcessingEnv,
+ element: XTypeElement,
+ paparazziShowkaseScreenshotTestTypeMirror: XType
+ ) {
+ val paparazziShowkaseScreenshotTestCompanionType = environment
+ .requireType(PAPARAZZI_SHOWKASE_SCREENSHOT_TEST_COMPANION_CLASS_NAME)
+
+ val companionObjectTypeElements = element.getEnclosedTypeElements().filter {
+ it.isCompanionObject()
+ }
+ if (companionObjectTypeElements.isEmpty()) {
+ throw ShowkaseProcessorException(
+ "Classes implementing the ${paparazziShowkaseScreenshotTestTypeMirror.typeName} interface " +
+ "should have a companion object that implements the " +
+ "${paparazziShowkaseScreenshotTestCompanionType.typeName} interface.",
+ element
+ )
+ }
+
+ if (!paparazziShowkaseScreenshotTestCompanionType
+ .isAssignableFrom(companionObjectTypeElements[0].type)) {
+ throw ShowkaseProcessorException(
+ "Classes implementing the ${paparazziShowkaseScreenshotTestTypeMirror.typeName} interface " +
+ "should have a companion object that implements the " +
+ "${paparazziShowkaseScreenshotTestCompanionType.typeName} interface.",
+ element
+ )
+ }
+ }
+
  private fun requireOpenClass(
  element: XTypeElement,
  annotationName: String,
@@ -377,5 +428,9 @@ internal class ShowkaseValidator {
  companion object {
  private const val SHOWKASE_SCREENSHOT_TEST_CLASS_NAME =
  "com.airbnb.android.showkase.screenshot.testing.ShowkaseScreenshotTest"
+ private const val PAPARAZZI_SHOWKASE_SCREENSHOT_TEST_CLASS_NAME =
+ "com.airbnb.android.showkase.screenshot.testing.paparazzi.PaparazziShowkaseScreenshotTest"
+ private const val PAPARAZZI_SHOWKASE_SCREENSHOT_TEST_COMPANION_CLASS_NAME =
+ "com.airbnb.android.showkase.screenshot.testing.paparazzi.PaparazziShowkaseScreenshotTest.CompanionObject"
  }
 }