Enable JaCoCo test coverage for debug builds

designcompose/build.gradle.kts

@@ -60,6 +60,7 @@ android {
             initWith(buildTypes.getByName("release"))
             matchingFallbacks.add("release")
         }
+        debug { enableUnitTestCoverage = true }
     }
 
     packaging {
@@ -69,10 +70,58 @@ android {
             add("META-INF/LGPL2.1")
         }
     }
-    testOptions { unitTests { isIncludeAndroidResources = true } }
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+            all { test ->
+                test.extensions.configure<JacocoTaskExtension> {
+                    // These classes are not supposed to be accessible
+                    excludes = listOf("jdk.internal.*")
+                    isIncludeNoLocationClasses =
+                        true // Include classes without location information
+                }
+            }
+        }
+    }
 }
 
-tasks.withType<Test> { jacoco { isEnabled = true } }
+tasks.register<JacocoReport>("jacocoUnitTestReport") {
+    group = "verification"
+    dependsOn(tasks.named("testDebugUnitTest"))
+
+    // Point Jacoco to the source code. This correctly finds both Java and Kotlin files.
+    val mainSourceSet = android.sourceSets.getByName("main").java.srcDirs
+    sourceDirectories.setFrom(files(mainSourceSet))
+
+    val jacocoExcludes =
+        listOf(
+            "**/R.class",
+            "**/R$*.class",
+            "**/BuildConfig.*",
+            "**/Manifest*.*",
+            "**/*Test*.*",
+            // Add other classes or packages to exclude from coverage as needed
+        )
+
+    // Point Jacoco to the classes that were generated by the compilation
+    classDirectories.setFrom(
+        files(
+            fileTree(layout.buildDirectory.dir("intermediates/javac/")) { exclude(jacocoExcludes) },
+            fileTree(layout.buildDirectory.dir("tmp/kotlin-classes/")) { exclude(jacocoExcludes) },
+        )
+    )
+    // Collect execution data from .exec and .ec files generated during test execution
+    executionData.setFrom(
+        files(fileTree(layout.buildDirectory) { include(listOf("**/*.exec", "**/*.ec")) })
+    )
+
+    reports {
+        html.required.set(true)
+        html.outputLocation.set(
+            project.layout.buildDirectory.dir("reports/jacoco/jacocoUnitTestReport")
+        )
+    }
+}
 
 // To simplify publishing of the entire SDK, make the DesignCompose publish tasks depend on the
 // Gradle Plugin's publish tasks