BAEL-809: Moved mockito-kotlin to existing mockito module (#2191)

* BAEL-809: Add Kotlin Mockito supporting code

* BAEL-809: Add references to kotlin-mockito library

* BAEL-809: Move kotlin-mockito to existing kotlin module

Some unused java classes that were in the kotlin-mockito
module were simply deleted instead of moved to the mockito
module.

kotlin/src/main/kotlin/com/baeldung/kotlin/mockito/BookService.kt

@@ -0,0 +1,6 @@
+package com.baeldung.kotlin
+
+interface BookService {
+    fun inStock(bookId: Int): Boolean
+    fun lend(bookId: Int, memberId: Int)
+}

kotlin/src/main/kotlin/com/baeldung/kotlin/mockito/LendBookManager.kt

@@ -0,0 +1,11 @@
+package com.baeldung.kotlin
+
+class LendBookManager(val bookService:BookService) {
+    fun checkout(bookId: Int, memberId: Int) {
+        if(bookService.inStock(bookId)) {
+            bookService.lend(bookId, memberId)
+        } else {
+            throw IllegalStateException("Book is not available")
+        }
+    }
+}

kotlin/src/test/kotlin/com/baeldung/kotlin/mockito/LendBookManagerTest.kt

@@ -0,0 +1,30 @@
+package com.baeldung.kotlin;
+
+import org.junit.Test
+import org.mockito.Mockito
+
+class LibraryManagementTest {
+    @Test(expected = IllegalStateException::class)
+    fun whenBookIsNotAvailable_thenAnExceptionIsThrown() {
+        val mockBookService = Mockito.mock(BookService::class.java)
+
+        Mockito.`when`(mockBookService.inStock(100)).thenReturn(false)
+
+        val manager = LendBookManager(mockBookService)
+
+        manager.checkout(100, 1)
+    }
+
+    @Test
+    fun whenBookIsAvailable_thenLendMethodIsCalled() {
+        val mockBookService = Mockito.mock(BookService::class.java)
+
+        Mockito.`when`(mockBookService.inStock(100)).thenReturn(true)
+
+        val manager = LendBookManager(mockBookService)
+
+        manager.checkout(100, 1)
+
+        Mockito.verify(mockBookService).lend(100, 1)
+    }
+}

kotlin/src/test/kotlin/com/baeldung/kotlin/mockito/LendBookManagerTestMockitoKotlin.kt

@@ -0,0 +1,32 @@
+package com.baeldung.kotlin;
+
+import com.nhaarman.mockito_kotlin.mock
+import com.nhaarman.mockito_kotlin.verify
+import com.nhaarman.mockito_kotlin.whenever
+import org.junit.Test
+
+class LibraryManagementTestMockitoKotlin {
+    @Test(expected = IllegalStateException::class)
+    fun whenBookIsNotAvailable_thenAnExceptionIsThrown() {
+        val mockBookService = mock<BookService>() 
+
+        whenever(mockBookService.inStock(100)).thenReturn(false)
+
+        val manager = LendBookManager(mockBookService)
+
+        manager.checkout(100, 1)
+    }
+
+    @Test
+    fun whenBookIsAvailable_thenLendMethodIsCalled() {
+        val mockBookService : BookService = mock()
+
+        whenever(mockBookService.inStock(100)).thenReturn(true)
+
+        val manager = LendBookManager(mockBookService)
+
+        manager.checkout(100, 1)
+
+        verify(mockBookService).lend(100, 1)
+    }
+}