JUnit 5 Fixture Extension

A Fixture is something you can

• set up and tear down
• use in a test
• identify by type and name
• give a scoped lifecycle (e.g. test method, class, file, session)

More about fixtures: https://docs.pytest.org/en/6.2.x/fixture.html

Add fixtures to your project

<dependency>
    <groupId>de.gofabian</groupId>
    <artifactId>junit-fixture-extension</artifactId>
    <version>0.1.1</version>
    <scope>test</scope>
</dependency>

Use fixtures in tests

With Fixture Extension	Plain JUnit 5
@ExtendWith(FixtureExtension.class) class TestClass { @Fixture Database db(FixtureContext c) { var db = DbUtil.open(...); c.addTearDown(() -> db.close()); return db; } @Test void test(Database db) { db.put("key", "value"); assertEquals("value", db.get("key")); } }	class TestClass { Database db; @BeforeEach void setUp() { db = DbUtil.open(...); } @AfterEach void tearDown() { db.close(); } @Test void test() { db.put("key", "value"); assertEquals("value", db.get("key")); } }

Use fixture scopes

@ExtendWith(FixtureExtension.class) class TestClass { @Fixture(scope = Scope.SESSION) long fixtureWithFileScope(FixtureContext c) { println("session-up"); c.addTearDown(() -> println("session-down")); return 1234567890; } @Fixture(scope = Scope.FILE) double fixtureWithFileScope(FixtureContext c) { println("file-up"); c.addTearDown(() -> println("file-down")); return 13.37; } @Fixture(scope = Scope.CLASS) int fixtureWithClassScope(FixtureContext c) { println("class-up"); c.addTearDown(() -> println("class-down")); return 42; } @Fixture // default scope is "METHOD" String fixtureWithMethodScope(FixtureContext c) { println("method-up"); c.addTearDown(() -> println("method-down")); return "method"; } @Test void test1(String m, int c, double f, long s) { println("test1"); } @Test void test2(String m, int c, double f, long s) { println("test2"); } }

Test Output: session-up file-up class-up method-up test1 method-down method-up test2 method-down class-down file-down session-down

Use fixtures in fixtures

@ExtendWith(FixtureExtension.class)
class TestClass {

    @Fixture
    Database db(FixtureContext c) {
        var db = DbUtil.open(...);
        c.addTearDown(() -> db.close());
        return db;
    }

    @Fixture
    Table bookTable(Database db) {
        return db.table("book");
    }

    @Test
    void test(Table table) {
        table.add("Science Book");
        assertEquals(1, table.count());
    }

}

Load fixtures from other classes

@ExtendWith(FixtureExtension.class) @LoadFixtures(DatabaseFixtures.class) class TestClass { @Fixture Table bookTable(Database db) { return db.table("book"); } @Test void test(Database db) { db.put("key", "value"); assertEquals("value", db.get("key")); } }

class DatabaseFixtures { @Fixture Database db(FixtureContext c) { var db = DbUtil.open(...); c.addTearDown(() -> db.close()); return db; } }

"Auto use" fixtures without explicit parameter

@ExtendWith(FixtureExtension.class)
class TestClass {

    @Fixture(autoUse = true)
    Database db(FixtureContext c) {
        var db = DbUtil.start(...);
        c.addTearDown(() -> db.stop());
        return db;
    }

    @Test
    void test(/* Database db */) {
        print("db is set up without explicit parameter");
    }

}

Use fixtures in nested tests

@ExtendWith(FixtureExtension.class) class TestClass { @Fixture(scope = Scope.FILE) double fixtureWithFileScope(FixtureContext c) { println("file-up"); c.addTearDown(() -> println("file-down")); return 13.37; } @Fixture(scope = Scope.CLASS) int fixtureWithClassScope(FixtureContext c) { println("class-up"); c.addTearDown(() -> println("class-down")); return 42; } @Nested class NestedTest1 { @Test void test1(String m, int c, double f, long s) { println("test1"); } } @Nested class NestedTest2 { @Test void test2(String m, int c, double f, long s) { println("test2"); } } }

Test Output: file-up class-up test1 class-down class-up test2 class-down file-down

Reference Fixture by type and optional name

@ExtendWith(FixtureExtension.class)
class TestClass {

    @Fixture
    String fixture1() {
        return "fixture1";
    }
    
    @Fixture
    String fixture2() {
        return "fixture2";
    }

    @Test
    void test(String fixture1, String fixture2, String any) {
        assertEquals("fixture1", fixture1);
        assertEquals("fixture2", fixture2);
        assertTrue(any.equals("fixture1") || any.equals("fixture2"));
    }

}

License

MIT License

Development

Run tests:

mvn test

Release

Set new version (implicit git tag and git push):

./bump_version.sh x.y.z

Create a release in Github and the Github workflow will automatically publish it to Maven Central.

Manual alternative:

mvn clean deploy -P release

Open Points

• generic dependency types, e.g. List
• @UseFixture
• support parallel execution
• support static fixture class methods
• fixture mark (given argument)
• parameterized fixture (multiple executions)
• more attributes in fixture context
• Programmatic FixtureDefinition