From 93aa0b94a4793376c9880f5f9904dacd93e013a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Pfr=C3=BCnder?= <joerg.pfruender@googlemail.com>
Date: Wed, 29 Dec 2021 10:45:58 +0100
Subject: [PATCH] add support for classes with one constructor but without
 annotation

---
 .../org/hypoport/mockito/MockInjector.java    | 27 ++++++++++++-----
 ...ructorInjectionClassWithoutAnnotation.java | 29 +++++++++++++++++++
 .../mockito/injection/MockInjectorTest.java   |  8 +++++
 3 files changed, 57 insertions(+), 7 deletions(-)
 create mode 100644 src/test/java/org/hypoport/mockito/injection/ConstructorInjectionClassWithoutAnnotation.java

diff --git a/src/main/java/org/hypoport/mockito/MockInjector.java b/src/main/java/org/hypoport/mockito/MockInjector.java
index 5246ee9..5147864 100644
--- a/src/main/java/org/hypoport/mockito/MockInjector.java
+++ b/src/main/java/org/hypoport/mockito/MockInjector.java
@@ -65,16 +65,15 @@ public static <T> T injectMocks(Class<T> clazz) {
       Constructor<?>[] constructors = clazz.getDeclaredConstructors();
       for (Constructor<?> constructor : constructors) {
         if (shouldBeInjected(constructor.getDeclaredAnnotations()) || constructor.getParameterTypes().length == 0) {
-          constructor.setAccessible(true);
-          Class<?>[] parameterTypes = constructor.getParameterTypes();
-          Object[] mocks = createMocksForParameterTypes(parameterTypes);
-          T instantiated = (T) constructor.newInstance(mocks);
-          injectFieldsAndSetters(instantiated, clazz);
-          return instantiated;
+          return createObjectAndInjectMocks(clazz, constructor);
         }
       }
+      // no annotated constructor found:
+      if (constructors.length == 1) {
+        return createObjectAndInjectMocks(clazz, constructors[0]);
+      }
       // we hopefully never get here:
-      throw new RuntimeException("no constructor found for class " + clazz);
+      throw new RuntimeException("no usable constructor found for class " + clazz);
     } catch (RuntimeException e) {
       throw e;
     } catch (Exception e) {
@@ -82,6 +81,20 @@ public static <T> T injectMocks(Class<T> clazz) {
     }
   }
 
+  private static <T> T createObjectAndInjectMocks(Class<T> clazz, Constructor<?> constructor) throws InstantiationException, IllegalAccessException, InvocationTargetException {
+    T instantiated = createObjectUsingConstructor(constructor);
+    injectFieldsAndSetters(instantiated, clazz);
+    return instantiated;
+  }
+
+  private static <T> T createObjectUsingConstructor(Constructor<?> constructor) throws InstantiationException, IllegalAccessException, InvocationTargetException {
+    constructor.setAccessible(true);
+    Class<?>[] parameterTypes = constructor.getParameterTypes();
+    Object[] mocks = createMocksForParameterTypes(parameterTypes);
+    T instantiated = (T) constructor.newInstance(mocks);
+    return instantiated;
+  }
+
   public static void injectFieldsAndSetters(Object object, Class<?> objectClass) throws IllegalAccessException, InvocationTargetException {
     injectFields(object, objectClass);
     injectSetter(object, objectClass);
diff --git a/src/test/java/org/hypoport/mockito/injection/ConstructorInjectionClassWithoutAnnotation.java b/src/test/java/org/hypoport/mockito/injection/ConstructorInjectionClassWithoutAnnotation.java
new file mode 100644
index 0000000..7a27b43
--- /dev/null
+++ b/src/test/java/org/hypoport/mockito/injection/ConstructorInjectionClassWithoutAnnotation.java
@@ -0,0 +1,29 @@
+/**
+ * Copyright 2022 HYPOPORT AG
+ *
+ *  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 org.hypoport.mockito.injection;
+
+import javax.inject.Inject;
+
+public class ConstructorInjectionClassWithoutAnnotation {
+
+  MyClass toBeInjected1;
+  Object toBeInjected2;
+
+  private ConstructorInjectionClassWithoutAnnotation(MyClass toBeInjected1, Object toBeInjected2) {
+    this.toBeInjected1 = toBeInjected1;
+    this.toBeInjected2 = toBeInjected2;
+  }
+}
diff --git a/src/test/java/org/hypoport/mockito/injection/MockInjectorTest.java b/src/test/java/org/hypoport/mockito/injection/MockInjectorTest.java
index 52ca784..0d1e88d 100644
--- a/src/test/java/org/hypoport/mockito/injection/MockInjectorTest.java
+++ b/src/test/java/org/hypoport/mockito/injection/MockInjectorTest.java
@@ -91,4 +91,12 @@ public void injectMocks_with_Class_can_handle_Constructor_Injection() {
     Assertions.assertThat(MockUtil.isMock(object.toBeInjected2)).isTrue();
   }
 
+  @Test
+  public void injectMocks_with_Class_can_handle_Constructor_Injection_without_annotation() {
+    ConstructorInjectionClassWithoutAnnotation object = MockInjector.injectMocks(ConstructorInjectionClassWithoutAnnotation.class);
+
+    Assertions.assertThat(MockUtil.isMock(object.toBeInjected1)).isTrue();
+    Assertions.assertThat(MockUtil.isMock(object.toBeInjected2)).isTrue();
+  }
+
 }