Learn how to check your Java purposes with JUnit 5

Itemizing 5. Logging the invocations of JUnit 5 lifecycle strategies (LifecycleDemoTest.java)

bundle com.javaworld.geekcap.lifecycle;

import org.junit.jupiter.api.*;

public class LifecycleDemoTest {

    @BeforeAll
    static void beforeAll() {
        System.out.println("Hook up with the database");
    }

    @BeforeEach
    void beforeEach() {
        System.out.println("Load the schema");
    }

    @AfterEach
    void afterEach() {
        System.out.println("Drop the schema");
    }

    @AfterAll
    static void afterAll() {
        System.out.println("Disconnect from the database");
    }

    @Check
    void testOne() {
        System.out.println("Check One");
    }

    @Check
    void testTwo() {
        System.out.println("Check Two");
    }
}

The output from operating this check prints the next:

Hook up with the database
Load the schema
Check One
Drop the schema
Load the schema
Check Two
Drop the schema
Disconnect from the database

As you’ll be able to see from this output, the beforeAll technique is named first and should do one thing like hook up with a database or create a big information construction into reminiscence. Subsequent, the beforeEach technique prepares the info for every check; for instance, by populating a check database with an anticipated set of knowledge. The primary check then runs, adopted by the afterEach technique. This course of (beforeEach—> check—>afterEach) continues till all of the exams have accomplished. Lastly, the afterAll technique cleans up the check surroundings, presumably by disconnecting from a database.

Earlier than wrapping up this preliminary introduction to testing with JUnit 5, I’ll present you methods to use tags to selectively run totally different sorts of check instances. Tags are used to establish and filter particular exams that you just need to run in varied eventualities. For instance, you would possibly tag one check class or technique as an integration check and one other as growth code. The names and makes use of of the tags are all as much as you.

We’ll create three new check lessons and tag two of them as growth and one as integration, presumably to distinguish between exams you need to run when constructing for various environments. Listings 6, 7, and eight present these three easy exams.

Itemizing 6. JUnit 5 tags, check 1 (TestOne.java)

bundle com.javaworld.geekcap.tags;

import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Check;

@Tag("Improvement")
class TestOne {
    @Check
    void testOne() {
        System.out.println("Check 1");
    }
}

Itemizing 7. JUnit 5 tags, check 2 (TestTwo.java)

bundle com.javaworld.geekcap.tags;

import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Check;

@Tag("Improvement")
class TestTwo {
    @Check
    void testTwo() {
        System.out.println("Check 2");
    }
}

Itemizing 8. JUnit 5 tags, check 3 (TestThree.java)

bundle com.javaworld.geekcap.tags;

import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Check;

@Tag("Integration")
class TestThree {
    @Check
    void testThree() {
        System.out.println("Check 3");
    }
}

Tags are carried out via annotations, and you’ll annotate both a whole check class or particular person strategies in a check class; moreover, a category or a way can have a number of tags. On this instance, TestOne and TestTwo are annotated with the “Improvement” tag, and TestThree is annotated with the “Integration” tag. We will filter check runs in numerous methods based mostly on tags. The best of those is to specify a check in your Maven command line; for instance, the next solely executes exams tagged as “Improvement”:

mvn clear check -Dgroups="Improvement"

The teams property permits you to specify a comma-separated listing of tag names for the exams that you really want JUnit 5 to run. Executing this yields the next output:

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Working com.javaworld.geekcap.tags.TestOne
Check 1
[INFO] Exams run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.029 s - in com.javaworld.geekcap.tags.TestOne
[INFO] Working com.javaworld.geekcap.tags.TestTwo
Check 2
[INFO] Exams run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.001 s - in com.javaworld.geekcap.tags.TestTwo

Likewise, we may execute simply the mixing exams as follows:

mvn clear check -Dgroups="Integration"

Or, we may execute each growth and integration exams:

mvn clear check -Dgroups="Improvement, Integration"

Along with the teams property, JUnit 5 permits you to use an excludedGroups property to execute all exams that shouldn’t have the required tag. For instance, in a growth surroundings, we don’t need to execute the mixing exams, so we may execute the next:

mvn clear check -DexcludedGroups="Integration"

That is useful as a result of a big utility can have actually hundreds of exams. If you happen to needed to create this environmental differentiation and add some new manufacturing exams, you wouldn’t need to have to return and add a “Improvement” tag to the opposite 10,000 exams.

Lastly, you’ll be able to add these similar teams and excludedGroups fields to the surefire plugin in your Maven POM file. You may also management these fields utilizing Maven profiles. I encourage you to evaluate the JUnit 5 consumer information to study extra about tags.

Conclusion

This text launched a number of the highlights of working with JUnit 5. I confirmed you methods to configure a Maven challenge to make use of JUnit 5 and methods to write exams utilizing the @Check and @ParameterizedTest annotations. I then launched the JUnit 5 lifecycle annotations, adopted by a take a look at the use and advantages of filter tags.