Add test rule to compare screenshots (#1)

jeslat · web-flow · commit 15abeac3b129 · 2025-06-06T12:35:39.000+02:00
diff --git a/app/src/androidTest/java/com/telefonica/loggerazzi/ExampleInstrumentedTest.kt b/app/src/androidTest/java/com/telefonica/loggerazzi/ExampleInstrumentedTest.kt
@@ -1,12 +1,11 @@
 package com.telefonica.loggerazzi
 
+import androidx.test.core.app.ActivityScenario
 import androidx.test.ext.junit.runners.AndroidJUnit4
-
+import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 
-import org.junit.Rule
-
 /**
  * Instrumented test, which will execute on an Android device.
  *
@@ -17,11 +16,12 @@ class ExampleInstrumentedTest {
 
     private val recorder = FakeTestRecorder()
 
-    @JvmField
-    @Rule
+    @get:Rule
     val loggerazziRule = LoggerazziRule(
         recorder = recorder
     )
+    @get:Rule
+    val screenshotsRule = ScreenshotsRule()
 
     @Test
     fun testSingleLog() {
@@ -41,16 +41,24 @@ class ExampleInstrumentedTest {
     }
 
     @Test
-    @IgnoreLoggerazzi
+    @IgnoreLogs
     fun testIgnoreLoggerazzi() {
         recorder.record("My log")
     }
 
     @Test
-    @IgnoreLoggerazzi
+    @IgnoreLogs
     fun testIgnoreLoggerazziWithoutGoldenFile() {
         recorder.record("My log")
     }
+
+    @Test
+    @IgnoreLogs
+    fun testLaunchActivity() {
+        ActivityScenario.launch(MainActivity::class.java).onActivity {
+            screenshotsRule.compareScreenshot(it, name = "launch_activity")
+        }
+    }
 }
 
 class FakeTestRecorder: LogsRecorder<String> {
diff --git a/app/src/androidTestDebug/assets/loggerazzi-golden-files/com.telefonica.loggerazzi.ExampleInstrumentedTest_launch_activity.png b/app/src/androidTestDebug/assets/loggerazzi-golden-files/com.telefonica.loggerazzi.ExampleInstrumentedTest_launch_activity.png
diff --git a/app/src/androidTestDebug/assets/loggerazzi-golden-files/com.telefonica.loggerazzi.ExampleInstrumentedTest_testLaunchActivity.txt b/app/src/androidTestDebug/assets/loggerazzi-golden-files/com.telefonica.loggerazzi.ExampleInstrumentedTest_testLaunchActivity.txt
diff --git a/build-tools/detekt/detekt.yml b/build-tools/detekt/detekt.yml
@@ -5,6 +5,8 @@ complexity:
     active: false
   LongMethod:
     ignoreAnnotated: 'Composable'
+  NestedBlockDepth:
+    threshold: 5
 
 style:
   NewLineAtEndOfFile:
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
@@ -14,6 +14,7 @@ detekt = "1.23.6"
 espresso-core = "3.6.1"
 junit = "4.13.2"
 publish = "2.0.0"
+ui-test-junit4-android = "1.8.2"
 
 [libraries]
 androidx-appcompat = { module = "androidx.appcompat:appcompat", version.ref = "appcompat" }
@@ -24,6 +25,9 @@ espresso-core = { module = "androidx.test.espresso:espresso-core", version.ref =
 espresso-junit = { module = "androidx.test.ext:junit", version.ref = "androidx-junit" }
 junit = { module = "junit:junit", version.ref = "junit" }
 material = { module = "com.google.android.material:material", version.ref = "material" }
+androidx-test-runner = { module = "androidx.test:runner", version = "1.6.2" }
+androidx-ui-test-junit4-android = { group = "androidx.compose.ui", name = "ui-test-junit4-android", version.ref = "ui-test-junit4-android" }
+differ = "com.dropbox.differ:differ:0.3.0"
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }
diff --git a/include-build/gradle-plugin/src/main/java/com/telefonica/loggerazzi/LoggerazziPlugin.kt b/include-build/gradle-plugin/src/main/java/com/telefonica/loggerazzi/LoggerazziPlugin.kt
@@ -147,7 +147,8 @@ class LoggerazziPlugin @Inject constructor(
                         file.delete()
                     }
                 }
-                lastFile?.renameTo(File(this, "$key.txt"))
+
+                lastFile?.renameTo(File(this, key))
             }
     }
 }
diff --git a/loggerazzi/build.gradle.kts b/loggerazzi/build.gradle.kts
@@ -36,10 +36,18 @@ android {
     }
 }
 
+kotlin {
+    explicitApi()
+}
+
 dependencies {
+    api(libs.differ)
+
     implementation(libs.core.ktx)
     implementation(libs.junit)
     implementation(libs.androidx.test.monitor)
+    implementation(libs.androidx.test.runner)
+    implementation(libs.androidx.ui.test.junit4.android)
 }
 
 apply("${rootProject.projectDir}/mavencentral.gradle")
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/BitmapImage.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/BitmapImage.kt
@@ -0,0 +1,18 @@
+package com.telefonica.loggerazzi
+
+import android.graphics.Bitmap
+import com.dropbox.differ.Color
+import com.dropbox.differ.Image
+import androidx.core.graphics.get
+
+internal class BitmapImage(private val src: Bitmap) : Image {
+  override val width: Int get() = src.width
+  override val height: Int get() = src.height
+  override fun getPixel(x: Int, y: Int): Color {
+    try {
+      return Color(src[x, y])
+    } catch (e: IllegalArgumentException) {
+      throw IllegalArgumentException("Can't request pixel {x = $x, y = $y} from image {width = $width, height = $height}", e)
+    }
+  }
+}
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/IgnoreLoggerazzi.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/IgnoreLoggerazzi.kt
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/Ignores.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/Ignores.kt
@@ -0,0 +1,10 @@
+package com.telefonica.loggerazzi
+
+
+@Retention(AnnotationRetention.RUNTIME)
+@Target(AnnotationTarget.FUNCTION)
+public annotation class IgnoreLogs
+
+@Retention(AnnotationRetention.RUNTIME)
+@Target(AnnotationTarget.FUNCTION)
+public annotation class IgnoreScreenshots
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/LogComparator.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/LogComparator.kt
@@ -2,11 +2,11 @@ package com.telefonica.loggerazzi
 
 import java.lang.StringBuilder
 
-interface LogComparator<LogType> {
-    fun compare(recorded: List<LogType>, golden: List<LogType>): String?
+public interface LogComparator<LogType> {
+    public fun compare(recorded: List<LogType>, golden: List<LogType>): String?
 }
 
-class DefaultLogComparator<LogType> : LogComparator<LogType> {
+public class DefaultLogComparator<LogType> : LogComparator<LogType> {
     override fun compare(recorded: List<LogType>, golden: List<LogType>): String? {
         if (recorded.size != golden.size) {
             return "Different number of lines: recorded=${recorded.size}, golden=${golden.size}"
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/LoggerazziRule.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/LoggerazziRule.kt
@@ -6,7 +6,7 @@ import org.junit.rules.TestWatcher
 import org.junit.runner.Description
 import java.io.File
 
-class LoggerazziRule(
+public class LoggerazziRule(
     recorder: LogsRecorder<String>,
     comparator: LogComparator<String> = DefaultLogComparator(),
 ) : GenericLoggerazziRule<String>(
@@ -18,8 +18,8 @@ class LoggerazziRule(
     comparator = comparator,
 )
 
-open class GenericLoggerazziRule<LogType>(
-    val recorder: LogsRecorder<LogType>,
+public open class GenericLoggerazziRule<LogType>(
+    public val recorder: LogsRecorder<LogType>,
     private val stringMapper: StringMapper<LogType>,
     private val comparator: LogComparator<LogType> = DefaultLogComparator(),
 ) : TestWatcher() {
@@ -48,10 +48,10 @@ open class GenericLoggerazziRule<LogType>(
     override fun succeeded(description: Description?) {
         super.succeeded(description)
 
-        val isTestIgnored = description?.getAnnotation(IgnoreLoggerazzi::class.java) != null
+        val isTestIgnored = description?.getAnnotation(IgnoreLogs::class.java) != null
 
         val testName = "${description?.className}_${description?.methodName}"
-        val fileName = "${testName}.${System.nanoTime()}"
+        val fileName = "${testName}.txt.${System.nanoTime()}"
 
         val recordedLogs = recorder.getRecordedLogs()
         val log = recordedLogs.joinToString("\n") { stringMapper.fromLog(it) }
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/LogsRecorder.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/LogsRecorder.kt
@@ -1,6 +1,6 @@
 package com.telefonica.loggerazzi
 
-interface LogsRecorder<LogType> {
-    fun clear()
-    fun getRecordedLogs(): List<LogType>
+public interface LogsRecorder<LogType> {
+    public fun clear()
+    public fun getRecordedLogs(): List<LogType>
 }
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/ResultValidator.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/ResultValidator.kt
@@ -0,0 +1,33 @@
+package com.telefonica.loggerazzi
+
+import com.dropbox.differ.ImageComparator
+import kotlin.math.roundToInt
+
+/**
+ * A function used to validate the comparison result.
+ */
+public typealias ResultValidator = (result: ImageComparator.ComparisonResult) -> Boolean
+
+/**
+ * Fails validation if there are more than `count` pixel differences.
+ */
+@Suppress("FunctionName")
+public fun CountValidator(count: Int) : ResultValidator {
+  require(count >= 0) { "count must be greater than or equal to 0." }
+  return { result ->
+    result.pixelDifferences <= count
+  }
+}
+
+/**
+ * Fails validation if more than `threshold` percent of pixels are different.
+ */
+@Suppress("FunctionName")
+public fun ThresholdValidator(threshold: Float) : ResultValidator {
+  require(threshold in 0f..1f) { "threshold must be in range 0.0..1.0"}
+  return { result ->
+    result.pixelDifferences <= (result.pixelCount * threshold).roundToInt()
+  }
+}
+
+
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/ScreenshotsRule.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/ScreenshotsRule.kt
@@ -0,0 +1,149 @@
+package com.telefonica.loggerazzi
+
+import android.app.Activity
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.os.Build
+import android.os.Environment
+import androidx.annotation.RequiresApi
+import androidx.compose.ui.graphics.asAndroidBitmap
+import androidx.compose.ui.test.captureToImage
+import androidx.compose.ui.test.junit4.ComposeTestRule
+import androidx.compose.ui.test.onRoot
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.runner.screenshot.Screenshot
+import com.dropbox.differ.ImageComparator
+import com.dropbox.differ.Mask
+import com.dropbox.differ.SimpleImageComparator
+import org.junit.rules.TestRule
+import org.junit.runner.Description
+import org.junit.runners.model.Statement
+import java.io.File
+import java.io.FileNotFoundException
+
+public class ScreenshotsRule(
+    private val imageComparator: ImageComparator = SimpleImageComparator(maxDistance = 0.004f),
+    private val resultValidator: ResultValidator = CountValidator(0),
+) : TestRule {
+
+    private var className: String = ""
+    private var testName: String = ""
+    private var isTestIgnored: Boolean = false
+    private val writeDiffImage = WriteDiffImage()
+
+    private val context = InstrumentationRegistry.getInstrumentation().context
+    private val downloadDir = File(
+        Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).absolutePath
+    )
+    private val loggerazziDir = File(downloadDir, "loggerazzi-logs/${context.packageName}")
+    private val failuresDir = File(loggerazziDir, "failures")
+    private val recordedDir = File(loggerazziDir, "recorded")
+
+    override fun apply(base: Statement, description: Description): Statement {
+        className = description.className
+        testName = description.methodName
+        isTestIgnored = description.getAnnotation(IgnoreScreenshots::class.java) != null
+
+        if (!failuresDir.exists()) {
+            failuresDir.mkdirs()
+        }
+        if (!recordedDir.exists()) {
+            recordedDir.mkdirs()
+        }
+        return base
+    }
+
+    @RequiresApi(Build.VERSION_CODES.O)
+    public fun compareScreenshot(
+        rule: ComposeTestRule,
+        name: String?,
+    ) {
+        rule.waitForIdle()
+        val bitmap = rule.onRoot().captureToImage().asAndroidBitmap()
+        compareScreenshot(bitmap, name)
+    }
+
+    public fun compareScreenshot(
+        activity: Activity,
+        name: String?,
+    ) {
+        val bitmap = Screenshot.capture(activity).bitmap
+        compareScreenshot(bitmap, name)
+    }
+
+    @Suppress("MemberVisibilityCanBePrivate")
+    public fun compareScreenshot(
+        bitmap: Bitmap,
+        name: String?
+    ) {
+        val resourceName = "${className}_${name ?: testName}.png"
+        val fileName = "$resourceName.${System.nanoTime()}"
+        saveScreenshot(fileName, bitmap)
+
+        if (InstrumentationRegistry.getArguments().getString("record") != "true" && !isTestIgnored) {
+            val goldenBitmap = getGoldenBitmap(resourceName)
+            compareImagesSize(bitmap, goldenBitmap, fileName, name)
+            compareImages(bitmap, goldenBitmap, fileName, resourceName)
+        }
+    }
+
+    private fun saveScreenshot(fileName: String, bitmap: Bitmap) {
+        val testFile = File(recordedDir, fileName)
+        testFile.createNewFile()
+        testFile.outputStream().use {
+            bitmap.compress(Bitmap.CompressFormat.PNG, 100, it)
+        }
+    }
+
+    private fun getGoldenBitmap(resourceName: String): Bitmap {
+        val goldenBitmap = try {
+            context.assets.open("loggerazzi-golden-files/$resourceName").use {
+                BitmapFactory.decodeStream(it)
+            }
+        } catch (e: FileNotFoundException) {
+            throw IllegalStateException(
+                "Failed to find golden image named $resourceName. If this is a new test, you may need to record screenshots",
+                e
+            )
+        }
+        return goldenBitmap
+    }
+
+    private fun compareImagesSize(
+        bitmap: Bitmap,
+        goldenBitmap: Bitmap,
+        fileName: String,
+        name: String?
+    ) {
+        if (bitmap.width != goldenBitmap.width || bitmap.height != goldenBitmap.height) {
+            writeDiffImage(failuresDir, fileName, bitmap, goldenBitmap, null)
+            throw AssertionError(
+                "$name: Test image (w=${bitmap.width}, h=${bitmap.height}) differs in size" +
+                        " from reference image (w=${goldenBitmap.width}, h=${goldenBitmap.height}).\n",
+            )
+        }
+    }
+
+    private fun compareImages(
+        bitmap: Bitmap,
+        goldenBitmap: Bitmap,
+        fileName: String,
+        resourceName: String
+    ) {
+        val mask = Mask(bitmap.width, bitmap.height)
+        val result = try {
+            imageComparator.compare(BitmapImage(goldenBitmap), BitmapImage(bitmap), mask)
+        } catch (e: IllegalArgumentException) {
+            writeDiffImage(failuresDir, fileName, bitmap, goldenBitmap, mask)
+            throw AssertionError("Failed to compare images", e)
+        }
+
+        if (!resultValidator(result)) {
+            writeDiffImage(failuresDir, fileName, bitmap, goldenBitmap, mask)
+            throw AssertionError(
+                "\"$resourceName\" failed to match reference image. ${result.pixelDifferences} pixels differ " +
+                        "(${(result.pixelDifferences / result.pixelCount.toFloat()) * 100} %)"
+            )
+        }
+    }
+}
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/StringMapper.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/StringMapper.kt
diff --git a/loggerazzi/src/main/java/com/telefonica/loggerazzi/WriteDiffImage.kt b/loggerazzi/src/main/java/com/telefonica/loggerazzi/WriteDiffImage.kt

Original file line number	Diff line number	Diff line change
`@@ -147,7 +147,8 @@ class LoggerazziPlugin @Inject constructor(`
`147`	`147`	`file.delete()`
`148`	`148`	`}`
`149`	`149`	`}`
`150`		`- lastFile?.renameTo(File(this, "$key.txt"))`
	`150`	`+`
	`151`	`+ lastFile?.renameTo(File(this, key))`
`151`	`152`	`}`
`152`	`153`	`}`
`153`	`154`	`}`
Original file line number	Diff line number	Diff line change
`@@ -36,10 +36,18 @@ android {`
`36`	`36`	`}`
`37`	`37`	`}`
`38`	`38`
	`39`	`+kotlin {`
	`40`	`+ explicitApi()`
	`41`	`+}`
	`42`	`+`
`39`	`43`	`dependencies {`
	`44`	`+ api(libs.differ)`
	`45`	`+`
`40`	`46`	`implementation(libs.core.ktx)`
`41`	`47`	`implementation(libs.junit)`
`42`	`48`	`implementation(libs.androidx.test.monitor)`
	`49`	`+ implementation(libs.androidx.test.runner)`
	`50`	`+ implementation(libs.androidx.ui.test.junit4.android)`
`43`	`51`	`}`
`44`	`52`
`45`	`53`	`apply("${rootProject.projectDir}/mavencentral.gradle")`