Add function to stub an existing mock with lambda syntax

Author: nhaarman

mockito-kotlin/src/main/kotlin/com/nhaarman/mockitokotlin2/Mockito.kt

@@ -25,19 +25,12 @@
 
 package com.nhaarman.mockitokotlin2
 
-import org.mockito.InOrder
-import org.mockito.Incubating
-import org.mockito.MockSettings
-import org.mockito.MockingDetails
-import org.mockito.Mockito
+import org.mockito.*
 import org.mockito.invocation.InvocationOnMock
 import org.mockito.listeners.InvocationListener
 import org.mockito.mock.SerializableMode
-import org.mockito.stubbing.Answer
-import org.mockito.stubbing.OngoingStubbing
-import org.mockito.stubbing.Stubber
-import org.mockito.verification.VerificationMode
-import org.mockito.verification.VerificationWithTimeout
+import org.mockito.stubbing.*
+import org.mockito.verification.*
 import kotlin.DeprecationLevel.WARNING
 import kotlin.reflect.KClass
 
@@ -178,6 +171,8 @@ inline fun <reified T : Any> mock(
     KStubbing(this).stubbing(this)
 }!!
 
+inline fun <T> stubbing(mock: T, stubbing: KStubbing<T>.(T) -> Unit) = KStubbing(mock).stubbing(mock)
+
 inline fun <T : Any> T.stub(stubbing: KStubbing<T>.(T) -> Unit) = this.apply { KStubbing(this).stubbing(this) }
 
 @Deprecated("Use mock() with optional arguments instead.", ReplaceWith("mock<T>(defaultAnswer = a)"), level = WARNING)

mockito-kotlin/src/test/kotlin/test/MockitoTest.kt

@@ -1052,4 +1052,18 @@ class MockitoTest : TestBase() {
             verify(this).nullableString(same(null))
         }
     }
+
+    @Test
+    fun stubbingExistingMock() {
+        /* Given */
+        val mock = mock<Methods>()
+
+        /* When */
+        stubbing(mock) {
+            on { stringResult() } doReturn "result"
+        }
+
+        /* Then */
+        expect(mock.stringResult()).toBe("result")
+    }
 }