我想评论一下这个问题的解决方案，它避免了任何与异常相关的JUnit代码。

我使用assertTrue（布尔值）和try/catch组合来查找要抛出的预期异常。下面是一个示例：

public void testConstructor() {
    boolean expectedExceptionThrown;
    try {
        // Call constructor with bad arguments
        double a = 1;
        double b = 2;
        double c = a + b; // In my example, this is an invalid option for c
        new Triangle(a, b, c);
        expectedExceptionThrown = false; // because it successfully constructed the object
    }
    catch(IllegalArgumentException e) {
        expectedExceptionThrown = true; // because I'm in this catch block
    }
    catch(Exception e) {
        expectedExceptionThrown = false; // because it threw an exception but not the one expected
    }
    assertTrue(expectedExceptionThrown);
}

只需制作一个可以关闭和打开的Matcher，如下所示：

public class ExceptionMatcher extends BaseMatcher<Throwable> {
    private boolean active = true;
    private Class<? extends Throwable> throwable;

    public ExceptionMatcher(Class<? extends Throwable> throwable) {
        this.throwable = throwable;
    }

    public void on() {
        this.active = true;
    }

    public void off() {
        this.active = false;
    }

    @Override
    public boolean matches(Object object) {
        return active && throwable.isAssignableFrom(object.getClass());
    }

    @Override
    public void describeTo(Description description) {
        description.appendText("not the covered exception type");
    }
}

要使用它：

add public ExpectedException exception=ExpectedException.none（）；，那么：

ExceptionMatcher exMatch = new ExceptionMatcher(MyException.class);
exception.expect(exMatch);
someObject.somethingThatThrowsMyException();
exMatch.off();

小心使用预期的异常，因为它只断言方法抛出了该异常，而不是测试中的特定代码行。

我倾向于将其用于测试参数验证，因为这样的方法通常非常简单，但更复杂的测试可能更好：

try {
    methodThatShouldThrow();
    fail( "My method didn't throw when I expected it to" );
} catch (MyException expectedException) {
}

应用判断。

Java 8解决方案

如果您想要一个解决方案：

利用Java 8 lambda不依赖任何JUnit魔法允许您检查单个测试方法中的多个异常检查测试方法中特定的一组行（而不是整个测试方法中的任何未知行）是否引发异常生成引发的实际异常对象，以便您可以进一步检查它

下面是我编写的实用函数：

public final <T extends Throwable> T expectException( Class<T> exceptionClass, Runnable runnable )
{
    try
    {
        runnable.run();
    }
    catch( Throwable throwable )
    {
        if( throwable instanceof AssertionError && throwable.getCause() != null )
            throwable = throwable.getCause(); //allows testing for "assert x != null : new IllegalArgumentException();"
        assert exceptionClass.isInstance( throwable ) : throwable; //exception of the wrong kind was thrown.
        assert throwable.getClass() == exceptionClass : throwable; //exception thrown was a subclass, but not the exact class, expected.
        @SuppressWarnings( "unchecked" )
        T result = (T)throwable;
        return result;
    }
    assert false; //expected exception was not thrown.
    return null; //to keep the compiler happy.
}

（摘自我的博客）

使用方法如下：

@Test
public void testMyFunction()
{
    RuntimeException e = expectException( RuntimeException.class, () -> 
        {
            myFunction();
        } );
    assert e.getMessage().equals( "I haz fail!" );
}

public void myFunction()
{
    throw new RuntimeException( "I haz fail!" );
}

JUnit内置了对此的支持，并带有“expected”属性。

我想评论一下这个问题的解决方案，它避免了任何与异常相关的JUnit代码。

我使用assertTrue（布尔值）和try/catch组合来查找要抛出的预期异常。下面是一个示例：

public void testConstructor() {
    boolean expectedExceptionThrown;
    try {
        // Call constructor with bad arguments
        double a = 1;
        double b = 2;
        double c = a + b; // In my example, this is an invalid option for c
        new Triangle(a, b, c);
        expectedExceptionThrown = false; // because it successfully constructed the object
    }
    catch(IllegalArgumentException e) {
        expectedExceptionThrown = true; // because I'm in this catch block
    }
    catch(Exception e) {
        expectedExceptionThrown = false; // because it threw an exception but not the one expected
    }
    assertTrue(expectedExceptionThrown);
}