Posts Tagged ‘junit’

Starting with the version 2.17.0 Mockito provides the official (built-in) support for managing a mocking life cycle if JUnit 5 is used.

mockito-junit5-logo

Getting started

To take advantage of the integration, the Mockito’s mockito-junit-jupiter dependency is required to be added next to the JUnit 5’s junit-platform-engine one (see below for details).

After that, the new Mockito extension MockitoExtension for JUnit 5 has to be enabled. And that’s enough. All the Mockito annotation should automatically start to work.

import org.junit.jupiter.api.Test;  //do not confuse with 'org.junit.Test'!
//other imports
import org.mockito.junit.jupiter.MockitoExtension;

@ExtendWith(MockitoExtension.class)
class SpaceShipJUnit5Test {

    @InjectMocks
    private SpaceShip spaceShip;

    @Mock
    private TacticalStation tacticalStation;

    @Mock
    private OperationsStation operationsStation;

    @Test
    void shouldInjectMocks() {
        assertThat(spaceShip).isNotNull();
        assertThat(tacticalStation).isNotNull();
        assertThat(operationsStation).isNotNull();
        assertThat(spaceShip.getTacticalStation()).isSameAs(tacticalStation);
        assertThat(spaceShip.getOperationsStation()).isSameAs(operationsStation);
    }
}

It’s nice that both a test class and test methods don’t need to be public anymore.

Please note. Having also JUnit 4 on a classpath (e.g. via junit-vintage-engine) for the “legacy” part of tests it is important to do not confuse org.junit.jupiter.api.Test with the old one org.junit.Test. It will not work.

Stubbing and verification

If for some reasons you are not a fan of AssertJ (although, I encourage you to at least give it a try) JUnit 5 provides a native assertion assertThrows (which is very similar to assertThatThrownBy() from AssertJ). It provides a meaningful error message in a case of an assertion failure.

@Test
void shouldMockSomething() {
    //given
    willThrow(SelfCheckException.class).given(tacticalStation).doSelfCheck();   //void method "given..will" not "when..then" cannot be used
    //when
    Executable e = () -> spaceShip.doSelfCheck();
    //then
    assertThrows(SelfCheckException.class, e);
}

I were not myself if I would not mention here that leveraging support for default methods in interfaces available in AssertJ and mockito-java8 a lot of static imports can be made redundant.

@ExtendWith(MockitoExtension.class)
class SpaceShipJUnit5Test implements WithAssertions, WithBDDMockito {
    ...
}

Tweaking default behavior

It also worth to point our that using the JUnit 5 extension Mockito by default works in the “strict mode”. It means that – for example – unneeded stubbing will fail the test. While very often it is a code smell, there are some cases where that test construction is desired. To change the default behavior an @MockitoSettings annotation can be used.

@ExtendWith(MockitoExtension.class)
@MockitoSettings(strictness = Strictness.WARN)
class SpaceShipJUnitAdvTest implements WithAssertions, WithBDDMockito {
    ....
}

Dependencies

As I already mentioned, to start using it is required to add a Mockito’s mockito-junit-jupiter dependency next to a JUnit 5’s junit-platform-engine one. In a Gradle build it could look like:

dependencies {
    testCompile 'org.junit.vintage:junit-platform-engine:5.1.0'
    testCompile 'org.mockito:mockito-junit-jupiter:2.17.2'  //mockito-core is implicitly added

    testCompile 'org.junit.vintage:junit-vintage-engine:5.1.0'  //for JUnit 4.12 test execution, if needed
    testCompile 'org.assertj:assertj-core:3.9.1'    //if you like it (you should ;) )
}

Please note. Due to a bug with injecting mocks via constructor into final fields that I have found writing this blog post, it is recommended to use at least version 2.17.2 instead of 2.17.0. That “development” version is not available in the Maven Central and the extra Bintray repository has to be added.

repositories {
    mavenCentral()
    maven { url "https://dl.bintray.com/mockito/maven" }    //for development versions of Mockito
}

In addition, it would be a waste to do not use a brand new native support for JUnit 5 test execution in Gradle 4.6+.

test {
    useJUnitPlatform()
}

IntelliJ IDEA has provided JUnit support since 2016.2 (JUnit 5 Milestone 2 at that time). Eclipse Oxygen also seems to add support for JUnit 5 recently.

mockito-junit5-idea-results

Summary

It is really nice to have a native support for JUnit 5 in Mockito. Not getting ahead there is ongoing work to make it even better.
The feature has been implemented by Christian Schwarz and polished by Tim van der Lippe with great assist from a few other people.

The source code is available from GitHub.

Btw, are you wondering how JUnit 5 compares with Spock? I will be talking about that at GeeCON 2018.

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Tune up your JUnit test class template for Idea with the BDD-like syntax, Java 8 and the Mockito-AssertJ duo.

Topics covered in this article may seem trivial. However, from my trainer experience I know that (unfortunately) it is not a common practice. Therefore, I decided to write this short blog post to propagate them and to be able to refer to it in the future.

given-when-then-template

My favorite testing framework for Java (and Groovy) is Spock. However, its mocks are not suitable for some purpose and I still use Mockito in various places. In addition, I still conduct a lot of my testing training in a JUnit/Mockito/AssertJ variant for teams which already have a test suite in that stack and would like to improve their skills without changing the known technology. Therefore, as an interlude, this blog post about testing in the pure Java style and propose how to tune up your JUnit testing framework assuming that you are already using Mockito and AssertJ (you should give them a try in the other case).

This blog post consists of tree parts. Firstly, I propose a BDD-style section-based test structure to keep your test more consist and more readable. Next, I explain how simplify – using the AssertJ and Mockito – constructions with Java 8. Last, but not least, I show how to configure it in IntelliJ IDEA as a default JUnit test (class) template (which isn’t as trivial as it should).

Part 1. BDD-style sections

Well written unit tests should meet several requirements (but it is a topic for a separate post). One of the useful practices is a clear separation into 3 code blocks with precisely defined responsibility. You can read more on that topic in my previous blog post.

As a repetition just the core rules presented in a short form:

  • given – an object under test initialization + stubs/mocks creation, stubbing and injection
  • when – an operation to test in a given test
  • then – received result assertion + mocks verification (if needed)
@Test
public void shouldXXX() {
  //given
  ...
  //when
  ...
  //then
  ...
}

That separation helps to keep tests short and focused on just one responsibility to test (in the end it’s just an unit test).

In Spock those sections are mandatory (*) – without them a test will not even compile. In JUnit there are just comments. However, having them in place encourage people to use them instead of having one big block of mess inside (especially useful for newbies in a testing area).

Btw, the mentioned given-when-then convention is based on (is a subset of) a much wider Behavior-Driven Development concept. You may encounter a similar division on 3 code blocks named arrange-act-assert which in general is an equivalent.

Part 2. Java 8 for AssertJ and Mockito

One of the features of Java 8 is an ability to put default methods in an interface. That can be used to simplify of calling static methods which is prevalent in the testing frameworks such as AssertJ and Mockito. The idea is simple. A test class willing to use a given framework can implement a dedicated interface to “see” those methods as its own methods on code completion in an IDE (instead of static methods from external class which require giving a class name before or a static import). Under the hood those default methods just delegate execution to static methods. You can read more about it in my other blog post.

AssertJ natively supports those construction starting with version 3.0.0. Mockito 1.10 and 2.x are Java 6 compatible and therefore it is required to use a 3rd-party project – mockito-java8 (which should be integrated into Mockito 3 – once available).

To benefit from easier method completion in Idea it is enough to implement two interfaces:

import info.solidsoft.mockito.java8.api.WithBDDMockito;
import org.assertj.core.api.WithAssertions;

class SampleTest implements WithAssertions, WithBDDMockito {

}

Part 3. Default template in Idea

I’m a big enthusiast of omnipresent automation. Wouldn’t it be good to have both given-when-then sections and extra interfaces automatically in place in your test classes? Let’s eliminate those boring things from our life.

Test method

Changing a JUnit test method is easy. One of the possible ways is “CTRL-SHIFT-A -> File Template -> Code” and a modification of JUnit4 Test Method to:

@org.junit.Test
public void should${NAME}() {
  //given
  ${BODY}
  //when
  //then
}

To add a new test in an existing test class just press ALT-INSERT and select (or type) JUnit4 Test Method.

Test class

With the whole test class the situation is a little bit more complicated. Idea provides a way to edit existing templates, however, it is used only if a test is generated with CTRL-SHIFT-T from a production class. It’s not very handy with TDD where a test should be created first. It would be good to have a new position “New JUnit test class” next to “Java class” displayed if ALT-INSERT is pressed being in a package view in a test context. Unfortunately, to do that a new plugin would need to be written (a sample implementation for Spock). As a workaround we can define a regular file template which (as a limitation) will be accessible everywhere (e.g. even in a resource directory).

Do “CTRL-SHIFT-A -> File Template -> Files”, press INSERT, name template “JUnit with AssertJ and Mockito Test”, set extension to “java” and paste the following template:

package ${PACKAGE_NAME};

import info.solidsoft.mockito.java8.api.WithBDDMockito;
import org.assertj.core.api.WithAssertions;

#parse("File Header.java") 
public class ${NAME} implements WithAssertions, WithBDDMockito {

}

Showcase

We are already set. Let’s check how it can look in practice (click to enlarge the animation).

idea-test-templates-in-action

Summary

I hope I convinced you to tune your test template to improve readability of your tests and to safe several keystrokes per test. In that case, please spend 4 minutes right now to configure it in your Idea. Depending on a number of tests written it may start to pay off sooner than you expect :).

Btw, at the beginning of October I will be giving a presentation about new features in Mockito 2 at JDD in Kraków.

JDD logo

Self promotion. Would you like to improve your and your team testing skills and knowledge of Spock/JUnit/Mockito/AssertJ quickly and efficiently? I conduct a condensed (unit) testing training which you may find useful.

Recently I wanted to configure an ability to run both TestNG and JUnit tests in one Maven module (project). At the end I managed how to do it clean and short, but before that I have found a few different solutions on the web (top 5 in Google) which part of them didn’t work and the rest applied to the earlier versions of Surefire plugin and was overly complicated (e.g. two separate executions). Therefore I decided to write this short post to show how it could be done in Surefire 2.13 – the newest version available in March 2013.

Mixing those tests frameworks in one module can be done just by adding both JUnit and TestNG as a plugin dependencies (not as project dependencies):

<plugin>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>${surefire.version}</version>
    <dependencies>
        <dependency>
            <groupId>org.apache.maven.surefire</groupId>
            <artifactId>surefire-junit47</artifactId>
            <version>${surefire.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.maven.surefire</groupId>
            <artifactId>surefire-testng</artifactId>
            <version>${surefire.version}</version>
        </dependency>
    </dependencies>
</plugin>

As the result both test types are executed.

[INFO] --- maven-surefire-plugin:2.13:test (default-test) @ junit-testng-poc ---
[INFO] Surefire report directory: /tmp/junit-testng-poc/target/surefire-reports
[INFO] Using configured provider org.apache.maven.surefire.junitcore.JUnitCoreProvider
[INFO] Using configured provider org.apache.maven.surefire.testng.TestNGProvider

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
parallel='none', perCoreThreadCount=true, threadCount=2, useUnlimitedThreads=false
Running info.solidsoft.rnd.junit.testng.SampleJUnitTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.253 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0


-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running TestSuite
Configuring TestNG with: TestNG652Configurator
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.869 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

Why to use TestNG with JUnit together? TestNG has a few features which are unavailable or less flexible in JUnit (just to mention a few: dependencies between tests and groups of tests (irreplaceable for integration tests with long startup), parametrized tests, concurrent execution or per suite/group/class init/shutdown operations). Therefore it is tempting to migrate existing tests from JUnit to TestNG. Having large code base it could be not so easy to migrate all of them at once and presented configuration allows to write the new tests in TestNG and rewrite the old tests when appropriate.

The whole working example can be found in my GitHub repository.

Btw, it is worth to mention that thanks to the fact TestNG generates reports also in the JUnit’s XML format all the tools compatible with JUnit (Jenkins, Sonar, …) will merge test results from JUnit and TestNG and display all of them properly.

Btw2, the same configuration works also with Failsafe plugin.

Btw3, thanks to the fact Spock Framework is under the hood a runner for JUnit presented trick can be used also to mix it with TestNG. This requires some additional work to integrate also Groovy and I plan to write about it in one of my future posts.