How to use should_return_empty_duration method of org.mockito.internal.stubbing.defaultanswers.ReturnsMocksTest class

You can just stub the calls to request.getHeaders etc. or if you can add a dependency, Spring-test has a MockHttpServletRequest that you could use (see here)

MockHttpServletRequest request = new MockHttpServletRequest();
request.addHeader("x-real-ip","127.0.0.1");

Or you could build your own implementation which allows you to set headers.

It's a defect in Mockito with loading plugins when context class loader is different from which is used to load PowerMock and Mockito.

It could be fixed in Mockito 2, but as it mentioned in comments

Not sure we have the build infrastructure to backport the fix on 1.x

For Mockito 1, fix cannot be delivered, so I fixed in in PowerMock and fix will be include in next PowerMock release (PowerMock 1.6.5).

What do you want it to do?

You can set it to RETURN_SMART_NULLS, which avoids the NPE and includes some useful info.

You could replace this with a custom implementation, for example, that throws an exception from its answer method:

@Test
public void test() {
    Object mock = Mockito.mock(Object.class, new NullPointerExceptionAnswer());
    String s = mock.toString(); // Breaks here, as intended.
    assertEquals("", s);
}

class NullPointerExceptionAnswer<T> implements Answer<T> {
    @Override
    public T answer(InvocationOnMock invocation) throws Throwable {
        throw new NullPointerException();
    }
}

This org.junit.Test is a JUnit 4 annotation. A Junit5 test runner will not discover a test annotated with org.junit.Test.

A Junit5 test runner will discover a test annotated with org.junit.jupiter.api.Test.

So, this explains why you get "No Test found with Test Runner JUnit 5" when attempting to run a test context which does not contain any tests annotated with org.junit.jupiter.api.Test.

It sounds like you might be migrating from Junit4 to Junit5. If so, there are several changes you'll need to come to terms with. The Junit5 docs offer some useful tips including:

Annotations reside in the org.junit.jupiter.api package.

Assertions reside in org.junit.jupiter.api.Assertions.

Assumptions reside in org.junit.jupiter.api.Assumptions.

@Before and @After no longer exist; use @BeforeEach and @AfterEach instead.

@BeforeClass and @AfterClass no longer exist; use @BeforeAll and @AfterAll instead.

@Ignore no longer exists: use @Disabled or one of the other built-in execution conditions instead

@Category no longer exists; use @Tag instead.

@RunWith no longer exists; superseded by @ExtendWith.

@Rule and @ClassRule no longer exist; superseded by @ExtendWith and @RegisterExtension

I found this trying to solve a similar issue creating a Mockito stub with a Map parameter. I didn't want to write a custom matcher for the Map in question and then I found a more elegant solution: use the additional matchers in hamcrest-library with mockito's argThat:

when(mock.search(argThat(hasEntry("xpath", "PRICE"))).thenReturn("$100.00");

If you need to check against multiple entries then you can use other hamcrest goodies:

when(mock.search(argThat(allOf(hasEntry("xpath", "PRICE"), hasEntry("otherKey", "otherValue")))).thenReturn("$100.00");

This starts to get long with non-trivial maps, so I ended up extracting methods to collect the entry matchers and stuck them in our TestUtils:

import static org.hamcrest.Matchers.allOf;
import static org.hamcrest.Matchers.anyOf;
import static org.hamcrest.Matchers.hasEntry;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.hamcrest.Matcher;
---------------------------------
public static <K, V> Matcher<Map<K, V>> matchesEntriesIn(Map<K, V> map) {
    return allOf(buildMatcherArray(map));
}

public static <K, V> Matcher<Map<K, V>> matchesAnyEntryIn(Map<K, V> map) {
    return anyOf(buildMatcherArray(map));
}

@SuppressWarnings("unchecked")
private static <K, V> Matcher<Map<? extends K, ? extends V>>[] buildMatcherArray(Map<K, V> map) {
    List<Matcher<Map<? extends K, ? extends V>>> entries = new ArrayList<Matcher<Map<? extends K, ? extends V>>>();
    for (K key : map.keySet()) {
        entries.add(hasEntry(key, map.get(key)));
    }
    return entries.toArray(new Matcher[entries.size()]);
}

So I'm left with:

when(mock.search(argThat(matchesEntriesIn(map))).thenReturn("$100.00");
when(mock.search(argThat(matchesAnyEntryIn(map))).thenReturn("$100.00");

There's some ugliness associated with the generics and I'm suppressing one warning, but at least it's DRY and hidden away in the TestUtil.

One last note, beware the embedded hamcrest issues in JUnit 4.10. With Maven, I recommend importing hamcrest-library first and then JUnit 4.11 (now 4.12) and exclude hamcrest-core from JUnit just for good measure:

<dependency>
    <groupId>org.hamcrest</groupId>
    <artifactId>hamcrest-library</artifactId>
    <version>1.3</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
    <exclusions>
        <exclusion>
            <groupId>org.hamcrest</groupId>
            <artifactId>hamcrest-core</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-all</artifactId>
    <version>1.9.5</version>
    <scope>test</scope>
</dependency>

Edit: Sept 1, 2017 - Per some of the comments, I updated my answer to show my Mockito dependency, my imports in the test util, and a junit that is running green as of today:

import static blah.tool.testutil.TestUtil.matchesAnyEntryIn;
import static blah.tool.testutil.TestUtil.matchesEntriesIn;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.is;
import static org.mockito.Matchers.argThat;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

import java.util.HashMap;
import java.util.Map;

import org.junit.Test;

public class TestUtilTest {

    @Test
    public void test() {
        Map<Integer, String> expected = new HashMap<Integer, String>();
        expected.put(1, "One");
        expected.put(3, "Three");

        Map<Integer, String> actual = new HashMap<Integer, String>();
        actual.put(1, "One");
        actual.put(2, "Two");

        assertThat(actual, matchesAnyEntryIn(expected));

        expected.remove(3);
        expected.put(2, "Two");
        assertThat(actual, matchesEntriesIn(expected));
    }

    @Test
    public void mockitoTest() {
        SystemUnderTest sut = mock(SystemUnderTest.class);
        Map<Integer, String> expected = new HashMap<Integer, String>();
        expected.put(1, "One");
        expected.put(3, "Three");

        Map<Integer, String> actual = new HashMap<Integer, String>();
        actual.put(1, "One");

        when(sut.search(argThat(matchesAnyEntryIn(expected)))).thenReturn("Response");
        assertThat(sut.search(actual), is("Response"));
    }

    protected class SystemUnderTest {
        // We don't really care what this does
        public String search(Map<Integer, String> map) {
            if (map == null) return null;
            return map.get(0);
        }
    }
}

Mockito.verify(foo, Mockito.times(1)).add("1");
Mockito.verify(foo, Mockito.times(1)).add(Mockito.anyString());

The first verify checks the expected parametrized call and the second verify checks that there was only one call to add at all.

I think this should work:

    @PrepareForTest({UtilDatabaseSoldeAutoCdeCommon.class})
    public class SomeTest {
        @Mock
        UtilDatabaseSoldeAutoCdeCommon fakeSingletonInstance;   

        @Test
        public void test() {
             Whitebox.setInternalState(UtilDatabaseSoldeAutoCdeCommon.class, "instance", fakeSingletonInstance);
             // Write here your test
        }
    }

I downloaded your code and got it working locally, as long as I included the relevant import statements:

import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.junit.runner.RunWith;
import org.junit.Test;
...

Perhaps you're missing an import somewhere.

Follow these steps may help:

1.mock it (ex. mockito)

CloseableHttpResponse response = mock(CloseableHttpResponse.class);
HttpEntity entity = mock(HttpEntity.class);

2.apply some rules

when(response.getStatusLine()).thenReturn(new BasicStatusLine(HttpVersion.HTTP_1_1, HttpStatus.SC_OK, "FINE!"));
when(entity.getContent()).thenReturn(getClass().getClassLoader().getResourceAsStream("result.txt"));
when(response.getEntity()).thenReturn(entity);

3.use it

when(httpClient.execute((HttpGet) any())).thenReturn(response);