add tests for class

packages/pigeon/lib/src/kotlin/templates.dart

@@ -44,7 +44,7 @@ class ${kotlinInstanceManagerClassName(options)}(private val finalizationListene
 
   // Extends WeakReference and overrides the `equals` and `hashCode` methods using identity rather
   // than equality.
-  private class IdentityWeakReference<T : Any> : java.lang.ref.WeakReference<T> {
+  class IdentityWeakReference<T : Any> : java.lang.ref.WeakReference<T> {
     private val savedHashCode: Int
 
     constructor(instance: T) : this(instance, null)

packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/ProxyApiTests.gen.kt

@@ -77,7 +77,7 @@ class ProxyApiTestsPigeonInstanceManager(
 
   // Extends WeakReference and overrides the `equals` and `hashCode` methods using identity rather
   // than equality.
-  private class IdentityWeakReference<T : Any> : java.lang.ref.WeakReference<T> {
+  class IdentityWeakReference<T : Any> : java.lang.ref.WeakReference<T> {
     private val savedHashCode: Int
 
     constructor(instance: T) : this(instance, null)

packages/pigeon/platform_tests/test_plugin/android/src/test/kotlin/com/example/test_plugin/InstanceManagerTest.kt

@@ -191,6 +191,30 @@ class InstanceManagerTest {
     assertEquals(1L, instanceManager.getIdentifierForStrongReference(testObject2))
   }
 
+  @Test
+  fun identityWeakReferenceAreEqualWithSameInstance() {
+    val testObject = Any()
+
+    assertEquals(
+        ProxyApiTestsPigeonInstanceManager.IdentityWeakReference(testObject),
+        ProxyApiTestsPigeonInstanceManager.IdentityWeakReference(testObject))
+  }
+
+  @Test
+  fun identityWeakReferenceRemainsEqualAfterGetReturnsNull() {
+    var testObject: Any? = Any()
+
+    val reference = ProxyApiTestsPigeonInstanceManager.IdentityWeakReference(testObject!!)
+
+    // To allow for object to be garbage collected.
+    @Suppress("UNUSED_VALUE")
+    testObject = null
+    Runtime.getRuntime().gc()
+
+    assertNull(reference.get())
+    assertEquals(reference, reference)
+  }
+
   private fun createInstanceManager(): ProxyApiTestsPigeonInstanceManager {
     return ProxyApiTestsPigeonInstanceManager.create(
         object : ProxyApiTestsPigeonInstanceManager.PigeonFinalizationListener {