Add support of suspendable answers to BDD

Author: neworld

mockito-kotlin/src/main/kotlin/org/mockito/kotlin/BDDMockito.kt

@@ -28,6 +28,7 @@ package org.mockito.kotlin
 import org.mockito.BDDMockito
 import org.mockito.BDDMockito.BDDMyOngoingStubbing
 import org.mockito.invocation.InvocationOnMock
+import org.mockito.kotlin.internal.SuspendableAnswer
 import org.mockito.stubbing.Answer
 
 /**
@@ -65,6 +66,13 @@ infix fun <T> BDDMyOngoingStubbing<T>.willAnswer(value: (InvocationOnMock) -> T?
     return willAnswer { value(it) }
 }
 
+/**
+ * Alias for [BBDMyOngoingStubbing.willAnswer], accepting a suspend lambda.
+ */
+infix fun <T> BDDMyOngoingStubbing<T>.willSuspendableAnswer(value: suspend (InvocationOnMock) -> T?): BDDMockito.BDDMyOngoingStubbing<T> {
+    return willAnswer(SuspendableAnswer(value))
+}
+
 /**
  * Alias for [BBDMyOngoingStubbing.willReturn].
  */

mockito-kotlin/src/main/kotlin/org/mockito/kotlin/OngoingStubbing.kt

@@ -26,12 +26,10 @@
 package org.mockito.kotlin
 
 import org.mockito.Mockito
-import org.mockito.internal.invocation.InterceptedInvocation
 import org.mockito.invocation.InvocationOnMock
+import org.mockito.kotlin.internal.SuspendableAnswer
 import org.mockito.stubbing.Answer
 import org.mockito.stubbing.OngoingStubbing
-import kotlin.coroutines.Continuation
-import kotlin.coroutines.intrinsics.startCoroutineUninterceptedOrReturn
 import kotlin.reflect.KClass
 
 
@@ -128,13 +126,5 @@ infix fun <T> OngoingStubbing<T>.doAnswer(answer: (InvocationOnMock) -> T?): Ong
 }
 
 infix fun <T> OngoingStubbing<T>.doSuspendableAnswer(answer: suspend (InvocationOnMock) -> T?): OngoingStubbing<T> {
-    return thenAnswer {
-        //all suspend functions/lambdas has Continuation as the last argument.
-        //InvocationOnMock does not see last argument
-        val rawInvocation = it as InterceptedInvocation
-        val continuation = rawInvocation.rawArguments.last() as Continuation<T?>
-
-        // https://youtrack.jetbrains.com/issue/KT-33766#focus=Comments-27-3707299.0-0
-        answer.startCoroutineUninterceptedOrReturn(it, continuation)
-    }
+    return thenAnswer(SuspendableAnswer(answer))
 }

mockito-kotlin/src/main/kotlin/org/mockito/kotlin/internal/SuspendableAnswer.kt

@@ -0,0 +1,50 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2018 Niek Haarman
+ * Copyright (c) 2007 Mockito contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package org.mockito.kotlin.internal
+
+import org.mockito.internal.invocation.InterceptedInvocation
+import org.mockito.invocation.InvocationOnMock
+import org.mockito.stubbing.Answer
+import kotlin.coroutines.Continuation
+import kotlin.coroutines.intrinsics.startCoroutineUninterceptedOrReturn
+
+/**
+ * This class properly wraps suspendable lambda into [Answer]
+ */
+@Suppress("UNCHECKED_CAST")
+internal class SuspendableAnswer<T>(
+    private val body: suspend (InvocationOnMock) -> T?
+) : Answer<T> {
+    override fun answer(invocation: InvocationOnMock?): T {
+        //all suspend functions/lambdas has Continuation as the last argument.
+        //InvocationOnMock does not see last argument
+        val rawInvocation = invocation as InterceptedInvocation
+        val continuation = rawInvocation.rawArguments.last() as Continuation<T?>
+
+        // https://youtrack.jetbrains.com/issue/KT-33766#focus=Comments-27-3707299.0-0
+        return body.startCoroutineUninterceptedOrReturn(invocation, continuation) as T
+    }
+}

mockito-kotlin/src/test/kotlin/org/mockito/kotlin/BDDMockitoKtTest.kt

@@ -0,0 +1,43 @@
+package org.mockito.kotlin
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.withContext
+import org.junit.Test
+
+import org.junit.Assert.*
+
+class BDDMockitoKtTest {
+
+    @Test
+    fun willSuspendableAnswer_withoutArgument() = runBlocking {
+        val fixture: SomeInterface = mock()
+
+        given(fixture.suspending()).willSuspendableAnswer {
+            withContext(Dispatchers.Default) { 42 }
+        }
+
+        assertEquals(42, fixture.suspending())
+        then(fixture).should().suspending()
+        Unit
+    }
+
+    @Test
+    fun willSuspendableAnswer_witArgument() = runBlocking {
+        val fixture: SomeInterface = mock()
+
+        given(fixture.suspendingWithArg(any())).willSuspendableAnswer {
+            withContext(Dispatchers.Default) { it.getArgument<Int>(0) }
+        }
+
+        assertEquals(42, fixture.suspendingWithArg(42))
+        then(fixture).should().suspendingWithArg(42)
+        Unit
+    }
+}
+
+interface SomeInterface {
+
+    suspend fun suspending(): Int
+    suspend fun suspendingWithArg(arg: Int): Int
+}