我写了一个工厂来产生java.sql.Connection对象:
public class MySQLDatabaseConnectionFactory implements DatabaseConnectionFactory {
@Override public Connection getConnection() {
try {
return DriverManager.getConnection(...);
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
我想验证传递给DriverManager的参数。getConnection，但我不知道如何模拟静态方法。我的测试用例使用JUnit 4和Mockito。是否有一个好的方法来模拟/验证这个特定的用例?
当前回答
要模拟静态方法，您应该使用Powermock查看: https://github.com/powermock/powermock/wiki/MockStatic。 Mockito不提供这种功能。
你可以读到一篇关于mockito的文章: http://refcardz.dzone.com/refcardz/mockito
其他回答
在Mockito之上使用PowerMockito。
示例代码:
@RunWith(PowerMockRunner.class)
@PrepareForTest(DriverManager.class)
public class Mocker {
@Test
public void shouldVerifyParameters() throws Exception {
//given
PowerMockito.mockStatic(DriverManager.class);
BDDMockito.given(DriverManager.getConnection(...)).willReturn(...);
//when
sut.execute(); // System Under Test (sut)
//then
PowerMockito.verifyStatic();
DriverManager.getConnection(...);
}
更多信息:
为什么Mockito不模拟静态方法?
我也遇到过类似的问题。根据PowerMock的mockStatic文档，接受的答案对我不起作用，直到我做出了更改:@PrepareForTest(classthatcontainsstaticmethod .class)。
我不需要使用BDDMockito。
我的类:
public class SmokeRouteBuilder {
public static String smokeMessageId() {
try {
return InetAddress.getLocalHost().getHostAddress();
} catch (UnknownHostException e) {
log.error("Exception occurred while fetching localhost address", e);
return UUID.randomUUID().toString();
}
}
}
我的测试类:
@RunWith(PowerMockRunner.class)
@PrepareForTest(SmokeRouteBuilder.class)
public class SmokeRouteBuilderTest {
@Test
public void testSmokeMessageId_exception() throws UnknownHostException {
UUID id = UUID.randomUUID();
mockStatic(InetAddress.class);
mockStatic(UUID.class);
when(InetAddress.getLocalHost()).thenThrow(UnknownHostException.class);
when(UUID.randomUUID()).thenReturn(id);
assertEquals(id.toString(), SmokeRouteBuilder.smokeMessageId());
}
}
从Mockito 3.4.0开始，就可以在Mockito中模拟静态方法。 详情见:
https://github.com/mockito/mockito/releases/tag/v3.4.0
https://github.com/mockito/mockito/issues/1013
https://javadoc.io/doc/org.mockito/mockito-core/latest/org/mockito/Mockito.html#static_mocks
assertEquals("foo", Foo.method());
try (MockedStatic mocked = mockStatic(Foo.class)) {
mocked.when(Foo::method).thenReturn("bar");
assertEquals("bar", Foo.method());
mocked.verify(Foo::method);
}
assertEquals("foo", Foo.method());
在你的例子中，是这样的:
@Test
public void testStaticMockWithVerification() throws SQLException {
try (MockedStatic<DriverManager> dummy = Mockito.mockStatic(DriverManager.class)) {
DatabaseConnectionFactory factory = new MySQLDatabaseConnectionFactory();
dummy.when(() -> DriverManager.getConnection("arg1", "arg2", "arg3"))
.thenReturn(new Connection() {/*...*/});
factory.getConnection();
dummy.verify(() -> DriverManager.getConnection(eq("arg1"), eq("arg2"), eq("arg3")));
}
}
注意:模拟STATIC METHODS需要模拟内联依赖而不是模拟核心。
对于JUnit5也添加这个:
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-junit-jupiter</artifactId>
<version>${mockito.version}</version>
<scope>test</scope>
</dependency>
对于模仿静态函数，我能够这样做:
在helper类/对象中创建一个包装器函数。(使用名称变体可能有助于保持内容的分离和可维护。) 在代码中使用此包装器。(是的，代码的实现需要考虑到测试。) 模拟包装器函数。
包装器代码片段(不是真正的功能，只是为了说明)
class myWrapperClass ...
def myWrapperFunction (...) {
return theOriginalFunction (...)
}
当然，在一个包装器类中积累多个这样的函数可能有利于代码重用。
稍微重构一下:
public class MySQLDatabaseConnectionFactory implements DatabaseConnectionFactory {
ConnectionSupplier connectionSupplier = () -> SupplierDriverManager.getConnection();
public void setConnSupplier(ConnectionSupplier supplier) {
this.connectionSupplier = supplier;
}
@Override
public Connection getConnection() {
try {
return connectionSupplier.conn();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
@FunctionalInterface
interface ConnectionSupplier {
Connection conn();
}
}
然后你可以使用mockito:
MySQLDatabaseConnectionFactory.ConnectionSupplier connectionSupplier = mock(MySQLDatabaseConnectionFactory.ConnectionSupplier.class);
when(connectionSupplier.conn()).thenReturn(yourMockObject);
yourConnectionFactory.setConnSupplier(connectionSupplier);
