我有以下类-
public class A {
int a;
public A() {
this.a = 67;
}
public int get_a() {
return this.a;
}
public boolean is_a_even() {
if(this.get_a() % 2 == 0) {
return true;
} else{
return false;
}
}
}
我想模拟get_a((函数,以便它返回我希望它返回的值,所以我编写了以下测试-
@ExtendWith(MockitoExtension.class)
class ATest {
@Test
public void testing_if_call_from_another_function_is_mocked() {
A obj = new A();
A mock = Mockito.spy(obj);
Mockito.doReturn(2).when(mock).get_a();
assertTrue(obj.is_a_even());
}
}
但当我运行这个程序时,我会得到以下异常-
org.mockito.exceptions.misusing.UnnecessaryStubbingException:
Unnecessary stubbings detected.
Clean & maintainable test code requires zero unnecessary code.
Following stubbings are unnecessary (click to navigate to relevant line of code):
1. -> at com.example.demo.ATest.testing_if_call_from_another_function_is_mocked(ATest.java:19)
Please remove unnecessary stubbings or use 'lenient' strictness. More info: javadoc for UnnecessaryStubbingException class.
at org.mockito.junit.jupiter.MockitoExtension.afterEach(MockitoExtension.java:186)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeAfterEachCallbacks$11(TestMethodTestDescriptor.java:253)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeAllAfterMethodsOrCallbacks$12(TestMethodTestDescriptor.java:269)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeAllAfterMethodsOrCallbacks$13(TestMethodTestDescriptor.java:269)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeAllAfterMethodsOrCallbacks(TestMethodTestDescriptor.java:268)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeAfterEachCallbacks(TestMethodTestDescriptor.java:252)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:137)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:65)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:75)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:221)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
这是否意味着对get_a((的方法调用没有被模拟?如果是,我如何模拟将从另一个方法调用的方法?
让我们更深入地了解发生了什么以及原因。
当我们呼叫时
A mock = Mockito.spy(obj);
mockito创建了一个包装器对象,我们可以使用它来监视对象。我们使用这个间谍来模拟我们想要模拟的呼叫:
Mockito.doReturn(2).when(mock).get_a();
请注意,原始obj
保持不变。特别是,它的行为保持不变。如果我们使用obj
,它的行为就好像我们从未创建过间谍一样。
因此,如果我们调用
obj.is_a_even()
我们的模拟不会被使用。为了获得所需的行为,我们需要调用
mock.is_a_even()
然而,正确的解决方案是使类可测试,例如通过提供允许设置a
值的构造函数,例如:
public class A {
private final int a;
public A(int a) {
this.a = a;
}
public A() {
this(67);
}
...
}
有了这个设置,我们可以在不需要任何mock的情况下编写相同的测试。
三个备注:
我们应该尊重封装,即设置属性
private
,并使其只能通过访问器方法访问。我们应该支持
Mockito.when(mock.get_a()).thenReturn(2);
超过
Mockto.doReturn(2).when(mock).get_a();
由于前者在编译时保证类型安全,而后者则不保证。
在Java中,方法名称应该用
lowerCamelCase
而不是snake_case
编写(get_a()
->getA()
,is_a_even()
->isAEven()
(。我还建议为字段a
以及这两种方法找到更好的名称。
由于从未调用mock.get_a()
,因此会得到UnnecessaryTubbingException。
这是因为你叫
assertTrue(obj.is_a_even());
代替:
assertTrue(mock.is_a_even());
因此,在is_a_even
方法中,this
指向obj
,而不是mock
其他备注:
- 坚持JavaBean命名约定-
getA()
而不是get_a()
。这是普遍存在的,许多工具都依赖于它 - 替换被测系统的一部分是一种先进的工具——要谨慎使用。如果可能的话,嘲笑SUT的合作者,而不是SUT本身