Fix handling of test subclasses

burst-gradle-plugin/src/test/kotlin/app/cash/burst/gradle/BurstGradlePluginTest.kt

@@ -303,6 +303,32 @@ class BurstGradlePluginTest {
     }
   }
 
+  /** https://github.com/cashapp/burst/issues/90 */
+  @Test
+  fun subclass() {
+    val projectDir = File("src/test/projects/subclass")
+
+    val taskName = ":lib:test"
+    val result = createRunner(projectDir, "clean", taskName).build()
+    assertThat(result.task(taskName)!!.outcome).isIn(*SUCCESS_OUTCOMES)
+
+    val testResults = projectDir.resolve("lib/build/test-results")
+    with(readTestSuite(testResults.resolve("test/TEST-CoffeeTest.xml"))) {
+      assertThat(testCases.map { it.name }).containsExactlyInAnyOrder(
+        "hasFakeOverride",
+        "hasFakeOverride_Oat",
+        "hasRealOverride",
+        "hasRealOverride_Oat",
+      )
+      assertThat(systemOut.trim().lines()).containsExactlyInAnyOrder(
+        "running fakeOverride Milk",
+        "running fakeOverride Oat",
+        "running realOverride Milk",
+        "running realOverride Oat",
+      )
+    }
+  }
+
   private fun createRunner(
     projectDir: File,
     vararg taskNames: String,

burst-gradle-plugin/src/test/projects/subclass/build.gradle.kts

@@ -0,0 +1,37 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+import org.jetbrains.kotlin.gradle.tasks.KotlinJvmCompile
+
+buildscript {
+  repositories {
+    maven {
+      url = file("$rootDir/../../../../../build/testMaven").toURI()
+    }
+    mavenCentral()
+    google()
+  }
+  dependencies {
+    classpath("app.cash.burst:burst-gradle-plugin:${project.property("burstVersion")}")
+    classpath(libs.kotlin.gradlePlugin)
+  }
+}
+
+allprojects {
+  repositories {
+    maven {
+      url = file("$rootDir/../../../../../build/testMaven").toURI()
+    }
+    mavenCentral()
+    google()
+  }
+
+  tasks.withType(JavaCompile::class.java).configureEach {
+    sourceCompatibility = "1.8"
+    targetCompatibility = "1.8"
+  }
+
+  tasks.withType(KotlinJvmCompile::class.java).configureEach {
+    compilerOptions {
+      jvmTarget.set(JvmTarget.JVM_1_8)
+    }
+  }
+}

burst-gradle-plugin/src/test/projects/subclass/lib/build.gradle.kts

@@ -0,0 +1,8 @@
+plugins {
+  kotlin("jvm")
+  id("app.cash.burst")
+}
+
+dependencies {
+  testImplementation(kotlin("test"))
+}

burst-gradle-plugin/src/test/projects/subclass/lib/src/test/kotlin/CoffeeTest.kt

@@ -0,0 +1,24 @@
+import app.cash.burst.Burst
+import app.cash.burst.burstValues
+import kotlin.test.Test
+
+@Burst
+class CoffeeTest : BaseCoffeeTest() {
+  @Test
+  override fun hasRealOverride(dairy: String) {
+    println("running realOverride $dairy")
+  }
+}
+
+@Burst
+abstract class BaseCoffeeTest {
+  @Test
+  open fun hasRealOverride(dairy: String = burstValues("Milk", "Oat")) {
+    error("unexpected call")
+  }
+
+  @Test
+  open fun hasFakeOverride(dairy: String = burstValues("Milk", "Oat")) {
+    println("running fakeOverride $dairy")
+  }
+}

burst-gradle-plugin/src/test/projects/subclass/settings.gradle.kts

@@ -0,0 +1,9 @@
+dependencyResolutionManagement {
+  versionCatalogs {
+    create("libs") {
+      from(files("../../../../../gradle/libs.versions.toml"))
+    }
+  }
+}
+
+include(":lib")

burst-kotlin-plugin/src/main/kotlin/app/cash/burst/kotlin/FunctionSpecializer.kt

@@ -72,6 +72,17 @@ internal class FunctionSpecializer(
     val originalDispatchReceiver = original.dispatchReceiverParameter
       ?: throw BurstCompilationException("Unexpected dispatch receiver", original)
 
+    // Drop `@Test` from the original's annotations.
+    original.annotations = original.annotations.filter {
+      it.type.classOrNull != testAnnotationClassSymbol
+    }
+
+    // Skip overrides. Burst will specialize the overridden function, and that's sufficient! (And
+    // we can't do anything here anyway, because overrides don't support default parameters.)
+    if (original.overriddenSymbols.isNotEmpty()) {
+      return
+    }
+
     val specializations = specializations(pluginContext, burstApis, valueParameters)
     val indexOfDefaultSpecialization = specializations.indexOfFirst { it.isDefault }
 
@@ -83,11 +94,6 @@ internal class FunctionSpecializer(
       )
     }
 
-    // Drop `@Test` from the original's annotations.
-    original.annotations = original.annotations.filter {
-      it.type.classOrNull != testAnnotationClassSymbol
-    }
-
     // Add new declarations.
     for (function in functions) {
       originalParent.addDeclaration(function)