How to use toString method of org.mockito.internal.matchers.MatchersToStringTest class

My solution was to update my global ~/.gradle/gradle.properties file with the correct proxy settings:

org.gradle.daemon=true
systemProp.https.proxyHost=proxy.company.net
systemProp.https.proxyPort=8181
systemProp.http.proxyHost=proxy.company.net
systemProp.http.proxyPort=8181
systemProp.https.nonProxyHosts=*.company.com|localhost

this is in effect, the same as passing these as command line args to gradlew (./gradlew -Dhttp.proxyHost=xxx -Dhttp.proxyPort=xxx -Dhttps.proxyHost=xxx -Dhttps.proxyPort=xxx

I don't quite follow what problem you're having using Mockito. Assuming you create a mock of the interface that contains your myMethod() method, you can then verify only the parameters to the method that you are interested in. For example (assuming the interface is called MyInterface and using JUnit 4):

@Test
public void test() {
    MyInterface myInterface = mock(MyInterface.class);
    FooBar expectedFooBar = new FooBar();        

    // other testing stuff

    verify(myInterface).myMethod(any(), any(), eq(expectedFooBar), any(), ...);
}

You'll need to do a static import on the Mockito methods for this to work. The any() matcher doesn't care what value has been passed when verifying.

You can't avoid passing something for every argument in your method (even if it's only NULL).

From the docs:

Sometimes we need to stub with different return value/exception for the same method call. Typical use case could be mocking iterators. Original version of Mockito did not have this feature to promote simple mocking. For example, instead of iterators one could use Iterable or simply collections. Those offer natural ways of stubbing (e.g. using real collections). In rare scenarios stubbing consecutive calls could be useful, though:

when(mock.someMethod("some arg"))
   .thenThrow(new RuntimeException())
  .thenReturn("foo");

//First call: throws runtime exception:
mock.someMethod("some arg");

//Second call: prints "foo"
System.out.println(mock.someMethod("some arg"));

So in your case, you'd want:

when(myMock.doTheCall())
   .thenReturn("You failed")
   .thenReturn("Success");

You can use ByteArrayOutputStream which writes the data in memory. You can read this with a ByteArrayInputStream.

An alternative is to write an expecting OutputStream which fails as soon as you attempt to write an incorrect byte. This can be helpful to see exactly where/why a test fails.

If you are using Spring (the spring-test library specifically), you can simply use ReflectionTestUtils.setField instead of Whitebox.setInternalState

Right or wrong, I was able to get this to properly do the JsonSerialization/JsonDeserialization by modifying the original Address POJO with the following changes. Added the following imports:

import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;

Added the following annotations:

@JsonSerialize(using = LocalDateTimeSerializer.class)
@JsonDeserialize(using = LocalDateTimeDeserializer.class)
private LocalDateTime created;

According to the Mockito documentation you can set different behavior for consecutive method calls.

when(mock.someMethod("some arg"))
    .thenThrow(new RuntimeException())
    .thenReturn("foo");

In case of a void method you can do something similar (Mockito documentation)

doThrow(new RuntimeException())
    .doNothing()
    .when(mock).doSomething();

A seam is a place in the code that you can insert a modification in behavior. You created a seam when you setup injection of your dependency.

One way to take advantage of a seam is to insert some sort of fake. Fake's can be hand-rolled, as in your example, or be created with a tool, like Mockito.

So, a mock is a type of fake, and a fake is often used by taking advantage of a Seam.

As for your tests and the way you broke the dependency, that's pretty much how I would have done it.

If the contract of class A includes the fact that it calls method B of an object of type C, then you should test this by making a mock of type C, and verifying that method B has been called.

This implies that the contract of class A has sufficient detail that it talks about type C (which might be an interface or a class). So yes, we're talking about a level of specification that goes beyond just "system requirements", and goes some way to describing implementation.

This is normal for unit tests. When you are unit testing, you want to ensure that each unit is doing the "right thing", and that will usually include its interactions with other units. "Units" here might mean classes, or larger subsets of your application.

Update:

I feel that this doesn't apply just to verification, but to stubbing as well. As soon as you stub a method of a collaborator class, your unit test has become, in some sense, dependent on implementation. It's kind of in the nature of unit tests to be so. Since Mockito is as much about stubbing as it is about verification, the fact that you're using Mockito at all implies that you're going to run across this kind of dependency.

In my experience, if I change the implementation of a class, I often have to change the implementation of its unit tests to match. Typically, though, I won't have to change the inventory of what unit tests there are for the class; unless of course, the reason for the change was the existence of a condition that I failed to test earlier.

So this is what unit tests are about. A test that doesn't suffer from this kind of dependency on the way collaborator classes are used is really a sub-system test or an integration test. Of course, these are frequently written with JUnit too, and frequently involve the use of mocking. In my opinion, "JUnit" is a terrible name, for a product that lets us produce all different types of test.