How to properly match varargs in Mockito

问题

I\'ve been trying to get to mock a method with vararg parameters using Mockito:

interface A {
  B b(int x, int y, C... c);
}

A a = mock(A.class);
B b = mock(B.class);

when(a.b(anyInt(), anyInt(), any(C[].class))).thenReturn(b);
assertEquals(b, a.b(1, 2));

This doesn\'t work, however if I do this instead:

when(a.b(anyInt(), anyInt())).thenReturn(b);
assertEquals(b, a.b(1, 2));

This works, despite that I have completely omitted the varargs argument when stubbing the method.

Any clues?

回答1:

Mockito 1.8.1 introduced anyVararg() matcher:

when(a.b(anyInt(), anyInt(), Matchers.<String>anyVararg())).thenReturn(b);

Also see history for this: https://code.google.com/archive/p/mockito/issues/62

Edit new syntax after deprecation:

when(a.b(anyInt(), anyInt(), ArgumentMatchers.<String>any())).thenReturn(b);

回答2:

A somewhat undocumented feature: If you want to develop a custom Matcher that matches vararg arguments you need to have it implement org.mockito.internal.matchers.VarargMatcher for it to work correctly. It's an empty marker interface, without which Mockito will not correctly compare arguments when invoking a method with varargs using your Matcher.

For example:

class MyVarargMatcher extends ArgumentMatcher<C[]> implements VarargMatcher {
    @Override public boolean matches(Object varargArgument) {
        return /* does it match? */ true;
    }
}

when(a.b(anyInt(), anyInt(), argThat(new MyVarargMatcher()))).thenReturn(b);

回答3:

Building on Eli Levine's answer here is a more generic solution:

import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.mockito.ArgumentMatcher;
import org.mockito.internal.matchers.VarargMatcher;

import static org.mockito.Matchers.argThat;

public class VarArgMatcher<T> extends ArgumentMatcher<T[]> implements VarargMatcher {

    public static <T> T[] varArgThat(Matcher<T[]> hamcrestMatcher) {
        argThat(new VarArgMatcher(hamcrestMatcher));
        return null;
    }

    private final Matcher<T[]> hamcrestMatcher;

    private VarArgMatcher(Matcher<T[]> hamcrestMatcher) {
        this.hamcrestMatcher = hamcrestMatcher;
    }

    @Override
    public boolean matches(Object o) {
        return hamcrestMatcher.matches(o);
    }

    @Override
    public void describeTo(Description description) {
        description.appendText("has varargs: ").appendDescriptionOf(hamcrestMatcher);
    }

}

Then you can use it with hamcrest's array matchers thus:

verify(a).b(VarArgMatcher.varArgThat(
            org.hamcrest.collection.IsArrayContaining.hasItemInArray("Test")));

(Obviously static imports will render this more readable.)

回答4:

I have been using the code in Peter Westmacott's answer however with Mockito 2.2.15 you can now do the following:

verify(a).method(100L, arg1, arg2, arg3)

where arg1, arg2, arg3 are varargs.

回答5:

Building on topchef's answer,

For 2.0.31-beta I had to use Mockito.anyVararg instead of Matchers.anyVararrg:

when(a.b(anyInt(), anyInt(), Mockito.<String>anyVararg())).thenReturn(b);

回答6:

In my case the signature of the method that I want to capture its argument is:

    public byte[] write(byte ... data) throws IOException;

In this case you should cast to byte array explicitly:

       when(spi.write((byte[])anyVararg())).thenReturn(someValue);

I'm using mockito version 1.10.19

回答7:

You can also loop over the arguments:

Object[] args = invocation.getArguments(); 
for( int argNo = 0; argNo < args.length; ++argNo) { 
    // ... do something with args[argNo] 
}

for example check their types and cast them appropriately, add to a list or whatever.

回答8:

Adapting the answer from @topchef,

Mockito.when(a.b(Mockito.anyInt(), Mockito.anyInt(), Mockito.any())).thenReturn(b);

Per the java docs for Mockito 2.23.4, Mockito.any() "Matches anything, including nulls and varargs."

回答9:

You can accomplish this by passing an ArgumentCaptor capture and then retrieving the varargs as a list using "getAllValues", see: https://stackoverflow.com/a/55621731/11342928

来源：https://stackoverflow.com/questions/2631596/how-to-properly-match-varargs-in-mockito

标签

java

mocking

variadic-functions

mockito