raisercostin raisercostin - 5 months ago 37
Java Question

mockito better expected exception test using spy

How can I make the 3rd test to check for the existence of cause1 in the message of the exception? I also listed in the first two tests that have drawbacks. First is not checking for the message second needs a lot of boilerplate code.

public class CheckExceptionsWithMockitoTest {

@Test(expected = RuntimeException.class)
public void testExpectedException1() {
A a = new A();
a.doSomethingThatThrows();
}

@Test
public void testExpectedException2() {
A a = new A();
try {
a.doSomethingThatThrows();
fail("no exception thrown");
} catch (RuntimeException e) {
assertThat(e.getMessage(), org.hamcrest.Matchers.containsString("cause1"));
}
}

@Test
public void testExpectedException3() {
A a = new A();
A spyA = org.mockito.Mockito.spy(a);
// valid but doesnt work
// doThrow(new IllegalArgumentException()).when(spyA).doSomethingThatThrows();
// invalid but in the spirit of what i want
//chekThrow(RuntimeException.class,containsString("cause1")).when(spyA).doSomethingThatThrows();
}

}


I couldn't find in Mockito something that works but there is something that looks like could be possible (at the level of syntax) and capabilities.




Using catchexception I created the test like this

import static com.googlecode.catchexception.CatchException.*;
import static com.googlecode.catchexception.apis.CatchExceptionHamcrestMatchers.*;
import static org.hamcrest.Matchers.*;
import static org.junit.Assert.*;

import org.junit.*;
public class CheckExceptionsWithMockitoTest{
//...
@Test
public void testExpectedException3() {
A a = new A();
verifyException(a,IllegalArgumentException.class)
.doSomethingThatThrows();
//if more details to be analized are needed
assertThat(
(IllegalStateException) caughtException(),
allOf(
is(IllegalStateException.class),
hasMessageThat(
containsString("is not allowed to add counterparties")),
hasNoCause()));
//more asserts could come
assertNotNull(a);
}
}

Answer

Use catch-exception library, or I guess that the solution you are looking for is your second implementation.

@expected doesn't provide any way to assert on the thrown exception except for its class, so you can't avoit try/catching (not that much boiler plate code !)

Mockito doesn't provide something likes a verifyThrows method.

So you can trade try/catching for an additional library : using catch-exception, you'll be able to catch exception in a single line and have it ready for further assertion(s).

Sample source code

A a = new A();

when(a).doSomethingThatThrows();

then(caughtException())
        .isInstanceOf(IllegalStateException.class)
        .hasMessageContaining("is not allowed to add counterparties")
        .hasNoCause();

Dependencies

'com.googlecode.catch-exception:catch-exception:1.2.0'
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