我正在尝试使用JUnit编写一种方法的单元测试，该方法只需获取特定的记录即可。我正在使用PowerMockito创建必要的模拟。但是，当我运行测试时，我得到了NullPointerException。
正在测试的方法如下：
public InputStream fetchBlankTemplate() {
MongoDatabase database = mongoClient.getDatabase("randomName");
MongoCollection<Document> collection = database.getCollection("Templates");
InputStream fileInputStream = new ByteArrayInputStream(
collection.find(Filters.eq("templateId", 1))
.first()
.get("file", Binary.class)
.getData());
mongoClient.close();
return fileInputStream;
}
上述方法的单元测试：
@RunWith(PowerMockRunner.class)
@PrepareForTest(DBConnection.class)
public class randomTest {
@InjectMocks
DBConnection dbcTest;
@Before
public void setUp() {
MockitoAnnotations.initMocks(this);
}
@SuppressWarnings("unchecked")
@Test
public void fetchBlankRecordTest() {
MongoClient mockClient = PowerMockito.mock(MongoClient.class);
MongoDatabase mockDatabase = PowerMockito.mock(MongoDatabase.class);
MongoCollection<Document> mockCollection = PowerMockito.mock(MongoCollection.class);
Binary mockBinary = PowerMockito.mock(Binary.class);
byte[] testByteArray = new byte[1000];
PowerMockito.when(mockClient.getDatabase("randomName")).thenReturn(mockDatabase);
PowerMockito.when(mockDatabase.getCollection("Templates")).thenReturn(mockCollection);
//getting NullPointerException for the line below
PowerMockito.when(mockCollection.find(Filters.eq("templateId", 1)).first().get("file", Binary.class).getData()).thenReturn(testByteArray);
InputStream testStream = dbcTest.fetchBlankTemplate();
assertNotNull(testStream);
}
}
堆栈跟踪如下：
at com.random.form_upload.test.randomTest.fetchBlankRecordTest(randomTest.java:68)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:68)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:326)
at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:89)
at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:97)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.executeTest(PowerMockJUnit44RunnerDelegateImpl.java:310)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTestInSuper(PowerMockJUnit47RunnerDelegateImpl.java:131)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.access$100(PowerMockJUnit47RunnerDelegateImpl.java:59)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner$TestExecutorStatement.evaluate(PowerMockJUnit47RunnerDelegateImpl.java:147)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.evaluateStatement(PowerMockJUnit47RunnerDelegateImpl.java:107)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTest(PowerMockJUnit47RunnerDelegateImpl.java:82)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runBeforesThenTestThenAfters(PowerMockJUnit44RunnerDelegateImpl.java:298)
at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:87)
at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:50)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.invokeTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:218)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.runMethods(PowerMockJUnit44RunnerDelegateImpl.java:160)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$1.run(PowerMockJUnit44RunnerDelegateImpl.java:134)
at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:34)
at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:44)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.run(PowerMockJUnit44RunnerDelegateImpl.java:136)
at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:121)
at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:57)
at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:59)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)
正在测试的方法按预期方式工作。问题出在单元测试中。我也可以肯定地确定
时会引发异常collection.find(Filters.eq("templateId", 1))
.first()
被调用。有什么想法吗？