Fixed KT-15963 (coroutines machinery should not use equals on results)

libraries/stdlib/test/coroutines/CoroutinesReferenceValuesTest.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2010-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package test.coroutines
+
+import kotlin.test.*
+import org.junit.Test
+import kotlin.coroutines.*
+
+/**
+ * Test to ensure that coroutine machinery does not call equals/hashCode/toString anywhere.
+ */
+class CoroutinesReferenceValuesTest {
+    class BadClass {
+        override fun equals(other: Any?): Boolean = error("equals")
+        override fun hashCode(): Int = error("hashCode")
+        override fun toString(): String = error("toString")
+    }
+
+    var counter = 0
+
+    // tail-suspend function via suspendCoroutine (test SafeContinuation)
+    suspend fun getBadClassViaSuspend(): BadClass = suspendCoroutine { cont ->
+        counter++
+        cont.resume(BadClass())
+    }
+
+    // state machine
+    suspend fun checkBadClassTwice() {
+        assertTrue(getBadClassViaSuspend() is BadClass)
+        assertTrue(getBadClassViaSuspend() is BadClass)
+    }
+
+    fun <T> suspend(block: suspend () -> T) = block
+
+    @Test
+    fun testBadClass() {
+        val bad = suspend {
+            checkBadClassTwice()
+            getBadClassViaSuspend()
+        }
+        var result: BadClass? = null
+        bad.startCoroutine(object : Continuation<BadClass> {
+            override val context: CoroutineContext = EmptyCoroutineContext
+
+            override fun resume(value: BadClass) {
+                assertTrue(result == null)
+                result = value
+            }
+
+            override fun resumeWithException(exception: Throwable) {
+                throw exception
+            }
+        })
+        assertTrue(result is BadClass)
+        assertEquals(3, counter)
+    }
+}