Add badging diff and colored output

build-plugin/build.gradle.kts

@@ -16,8 +16,8 @@ dependencies {
     implementation(plugin(libs.plugins.detekt))
     implementation(plugin(libs.plugins.dependency.check))
 
+    implementation(libs.diff.utils)
     compileOnly(libs.android.tools.common)
-    compileOnly(libs.assertk)
 }
 
 fun plugin(provider: Provider<PluginDependency>) = with(provider.get()) {

build-plugin/src/main/kotlin/thunderbird.quality.badging.gradle.kts

@@ -1,7 +1,7 @@
-import assertk.assertThat
-import assertk.assertions.isEqualTo
 import com.android.SdkConstants
 import com.android.build.api.artifact.SingleArtifact
+import com.github.difflib.text.DiffRow
+import com.github.difflib.text.DiffRowGenerator
 import org.gradle.configurationcache.extensions.capitalized
 
 /**
@@ -119,7 +119,8 @@ abstract class CheckBadgingTask : DefaultTask() {
     @TaskAction
     fun taskAction() {
         if (goldenBadging.isPresent.not()) {
-            logger.error(
+            printlnColor(
+                ANSI_YELLOW,
                 "Golden badging file does not exist!" +
                     " If this is the first time running this task," +
                     " run ./gradlew ${updateBadgingTaskName.get()}",
@@ -130,12 +131,85 @@ abstract class CheckBadgingTask : DefaultTask() {
         val goldenBadgingContent = goldenBadging.get().asFile.readText()
         val generatedBadgingContent = generatedBadging.get().asFile.readText()
         if (goldenBadgingContent == generatedBadgingContent) {
-            logger.info("Generated badging is the same as golden badging!")
+            printlnColor(ANSI_YELLOW, "Generated badging is the same as golden badging!")
             return
         }
 
-        assertThat(generatedBadgingContent).isEqualTo(goldenBadgingContent)
+        val diff = performDiff(goldenBadgingContent, generatedBadgingContent)
+        printDiff(diff)
+
+        throw GradleException(
+            """
+            Generated badging is different from golden badging!
+
+            If this change is intended, run ./gradlew ${updateBadgingTaskName.get()}
+            """.trimIndent(),
+        )
+    }
+
+    private fun performDiff(goldenBadgingContent: String, generatedBadgingContent: String): String {
+        val generator: DiffRowGenerator = DiffRowGenerator.create()
+            .showInlineDiffs(true)
+            .mergeOriginalRevised(true)
+            .inlineDiffByWord(true)
+            .oldTag { _ -> "" }
+            .newTag { _ -> "" }
+            .build()
+
+        return generator.generateDiffRows(
+            goldenBadgingContent.lines(),
+            generatedBadgingContent.lines(),
+        ).filter { row -> row.tag != DiffRow.Tag.EQUAL }
+            .joinToString("\n") { row ->
+                when (row.tag) {
+                    DiffRow.Tag.INSERT -> {
+                        "+ ${row.newLine}"
+                    }
+
+                    DiffRow.Tag.DELETE -> {
+                        "- ${row.oldLine}"
+                    }
+
+                    DiffRow.Tag.CHANGE -> {
+                        "+ ${row.newLine}"
+                        "- ${row.oldLine}"
+                    }
+
+                    DiffRow.Tag.EQUAL -> ""
+                }
             }
     }
 
+    private fun printDiff(diff: String) {
+        printlnColor("", null)
+        printlnColor(ANSI_YELLOW, "Badging diff:")
 
+        diff.lines().forEach { line ->
+            val ansiColor = if (line.startsWith("+")) {
+                ANSI_GREEN
+            } else if (line.startsWith("-")) {
+                ANSI_RED
+            } else {
+                null
+            }
+            printlnColor(line, ansiColor)
+        }
+    }
+
+    private fun printlnColor(text: String, ansiColor: String?) {
+        println(
+            if (ansiColor != null) {
+                ansiColor + text + ANSI_RESET
+            } else {
+                text
+            },
+        )
+    }
+
+    private companion object {
+        const val ANSI_RESET = "\u001B[0m"
+        const val ANSI_RED = "\u001B[31m"
+        const val ANSI_GREEN = "\u001B[32m"
+        const val ANSI_YELLOW = "\u001B[33m"
+    }
+}

gradle/libs.versions.toml

@@ -61,6 +61,7 @@ dependency-guard = { id = "com.dropbox.dependency-guard", version.ref = "pluginD
 [libraries]
 desugar = "com.android.tools:desugar_jdk_libs:2.0.4"
 android-tools-common = { group = "com.android.tools", name = "common", version.ref = "androidTools" }
+diff-utils = "io.github.java-diff-utils:java-diff-utils:4.12"
 
 kotlin-test = { module = "org.jetbrains.kotlin:kotlin-test", version.ref = "kotlin" }
 kotlin-reflect = { module = "org.jetbrains.kotlin:kotlin-reflect", version.ref = "kotlin" }