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
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>
其他回答
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
如前所述，你不能用mockito模拟静态方法。
如果改变你的测试框架不是一个选择，你可以做以下事情:
为DriverManager创建一个接口，模拟这个接口，通过某种依赖注入注入它，并在这个模拟上进行验证。
Mockito不能捕获静态方法，但是由于Mockito 2.14.0，您可以通过创建静态方法的调用实例来模拟它。
示例(从它们的测试中提取):
public class StaticMockingExperimentTest extends TestBase {
Foo mock = Mockito.mock(Foo.class);
MockHandler handler = Mockito.mockingDetails(mock).getMockHandler();
Method staticMethod;
InvocationFactory.RealMethodBehavior realMethod = new InvocationFactory.RealMethodBehavior() {
@Override
public Object call() throws Throwable {
return null;
}
};
@Before
public void before() throws Throwable {
staticMethod = Foo.class.getDeclaredMethod("staticMethod", String.class);
}
@Test
public void verify_static_method() throws Throwable {
//register staticMethod call on mock
Invocation invocation = Mockito.framework().getInvocationFactory().createInvocation(mock, withSettings().build(Foo.class), staticMethod, realMethod,
"some arg");
handler.handle(invocation);
//verify staticMethod on mock
//Mockito cannot capture static methods so we will simulate this scenario in 3 steps:
//1. Call standard 'verify' method. Internally, it will add verificationMode to the thread local state.
// Effectively, we indicate to Mockito that right now we are about to verify a method call on this mock.
verify(mock);
//2. Create the invocation instance using the new public API
// Mockito cannot capture static methods but we can create an invocation instance of that static invocation
Invocation verification = Mockito.framework().getInvocationFactory().createInvocation(mock, withSettings().build(Foo.class), staticMethod, realMethod,
"some arg");
//3. Make Mockito handle the static method invocation
// Mockito will find verification mode in thread local state and will try verify the invocation
handler.handle(verification);
//verify zero times, method with different argument
verify(mock, times(0));
Invocation differentArg = Mockito.framework().getInvocationFactory().createInvocation(mock, withSettings().build(Foo.class), staticMethod, realMethod,
"different arg");
handler.handle(differentArg);
}
@Test
public void stubbing_static_method() throws Throwable {
//register staticMethod call on mock
Invocation invocation = Mockito.framework().getInvocationFactory().createInvocation(mock, withSettings().build(Foo.class), staticMethod, realMethod,
"foo");
handler.handle(invocation);
//register stubbing
when(null).thenReturn("hey");
//validate stubbed return value
assertEquals("hey", handler.handle(invocation));
assertEquals("hey", handler.handle(invocation));
//default null value is returned if invoked with different argument
Invocation differentArg = Mockito.framework().getInvocationFactory().createInvocation(mock, withSettings().build(Foo.class), staticMethod, realMethod,
"different arg");
assertEquals(null, handler.handle(differentArg));
}
static class Foo {
private final String arg;
public Foo(String arg) {
this.arg = arg;
}
public static String staticMethod(String arg) {
return "";
}
@Override
public String toString() {
return "foo:" + arg;
}
}
}
他们的目标不是直接支持静态模拟，而是改进它的公共api，以便其他库(如Powermockito)不必依赖内部api或直接复制一些Mockito代码。(源)
Disclaimer: Mockito team thinks that the road to hell is paved with static methods. However, Mockito's job is not to protect your code from static methods. If you don’t like your team doing static mocking, stop using Powermockito in your organization. Mockito needs to evolve as a toolkit with an opinionated vision on how Java tests should be written (e.g. don't mock statics!!!). However, Mockito is not dogmatic. We don't want to block unrecommended use cases like static mocking. It's just not our job.
我还编写了Mockito和AspectJ的组合:https://github.com/iirekm/varia/tree/develop/ajmock
你的例子是:
when(() -> DriverManager.getConnection(...)).thenReturn(...);
观察:当您在静态实体中调用静态方法时，您需要更改@PrepareForTest中的类。
例如:
securityAlgo = MessageDigest.getInstance(SECURITY_ALGORITHM);
对于上面的代码，如果您需要模拟MessageDigest类，请使用
@PrepareForTest(MessageDigest.class)
而如果你有如下内容:
public class CustomObjectRule {
object = DatatypeConverter.printHexBinary(MessageDigest.getInstance(SECURITY_ALGORITHM)
.digest(message.getBytes(ENCODING)));
}
然后，您需要准备这个代码所在的类。
@PrepareForTest(CustomObjectRule.class)
然后模拟这个方法:
PowerMockito.mockStatic(MessageDigest.class);
PowerMockito.when(MessageDigest.getInstance(Mockito.anyString()))
.thenThrow(new RuntimeException());
