Properly handle sealed classes with Kotlin 1.7 and JDK 17

Attempt to fix mockk#832 by supporting sealed classes based on previous work done by @aSemy.
stuebingerb · Sep 6, 2022 · 80c7ea3 · 80c7ea3
1 parent 6c571a6
commit 80c7ea3
Show file tree

Hide file tree

Showing 3 changed files with 25 additions and 6 deletions.
diff --git a/modules/mockk-agent/src/jvmMain/kotlin/io/mockk/proxy/jvm/ObjenesisInstantiator.kt b/modules/mockk-agent/src/jvmMain/kotlin/io/mockk/proxy/jvm/ObjenesisInstantiator.kt
@@ -24,6 +24,10 @@ class ObjenesisInstantiator(
         if (cls == Any::class.java) {
             @Suppress("UNCHECKED_CAST")
             return Any() as T
+        } else if (cls.isSealedSafe()) {
+            cls.getPermittedSubclassesSafe().firstNotNullOfOrNull { subCls ->
+                runCatching { instance(subCls) }.getOrNull()
+            } ?: error("could not find subclass for sealed class $cls")
         } else if (!Modifier.isFinal(cls.modifiers)) {
             try {
                 val instance = instantiateViaProxy(cls)
@@ -42,6 +46,27 @@ class ObjenesisInstantiator(
         return instanceViaObjenesis(cls)
     }
 
+    /**
+     * `boolean Class.isSealed()` is only available with JDK 17+. Used via reflection to support
+     * builds with previous Java versions as well. This should be refactored to use the actual
+     * method once the minimum Java version is 17.
+     */
+    private fun Class<*>.isSealedSafe(): Boolean =
+        javaClass.methods.firstOrNull { it.name == "isSealed" }?.invoke(this) == true
+
+    /**
+     * `Class<?>[] Class.getPermittedSubclasses` is only available with JDK 17+. Used via reflection
+     * to support builds with previous Java versions as well. This should be refactored to use the
+     * actual method once the minimum Java version is 17.
+     */
+    private fun Class<*>.getPermittedSubclassesSafe(): Array<Class<*>> =
+        javaClass.methods.firstOrNull { it.name == "getPermittedSubclasses" }
+            ?.let {
+                @Suppress("UNCHECKED_CAST")
+                it.invoke(this) as Array<Class<*>>
+            }
+            ?: emptyArray()
+
     private fun <T> instantiateViaProxy(cls: Class<T>): T? {
         val proxyCls = if (!Modifier.isAbstract(cls.modifiers)) {
             log.trace("Skipping instantiation subsclassing $cls because class is not abstract.")

diff --git a/modules/mockk/src/commonTest/kotlin/io/mockk/it/SealedClassTest.kt b/modules/mockk/src/commonTest/kotlin/io/mockk/it/SealedClassTest.kt
@@ -2,15 +2,13 @@ package io.mockk.it
 
 import io.mockk.every
 import io.mockk.mockk
-import kotlin.test.Ignore
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
 
 class SealedClassTest {
 
     @Test
-    @Ignore("Fails on JDK17+ https://github.com/mockk/mockk/issues/832")
     fun serviceReturnsSealedClassImpl() {
         val factory = mockk<Factory> {
             every { create() } returns Leaf(1)
@@ -22,7 +20,6 @@ class SealedClassTest {
     }
 
     @Test
-    @Ignore("Fails on JDK17+ https://github.com/mockk/mockk/issues/832")
     fun serviceAnswersSealedClassImpl() {
         val factory = mockk<Factory> {
             every { create() } answers { Leaf(1) }

diff --git a/modules/mockk/src/commonTest/kotlin/io/mockk/it/SealedInterfaceTest.kt b/modules/mockk/src/commonTest/kotlin/io/mockk/it/SealedInterfaceTest.kt
@@ -3,14 +3,12 @@ package io.mockk.it
 import io.mockk.every
 import io.mockk.mockk
 import kotlin.test.Test
-import kotlin.test.Ignore
 import kotlin.test.assertEquals
 
 
 class SealedInterfaceTest {
 
     @Test
-    @Ignore("Fails on JDK17+ https://github.com/mockk/mockk/issues/832")
     fun serviceReturnsSealedClassImpl() {
         val factory = mockk<Factory> {
             every { create() } returns Leaf(1)
@@ -22,7 +20,6 @@ class SealedInterfaceTest {
     }
 
     @Test
-    @Ignore("Fails on JDK17+ https://github.com/mockk/mockk/issues/832")
     fun serviceAnswersSealedClassImpl() {
         val factory = mockk<Factory> {
             every { create() } answers { Leaf(1) }