SystemPropertyExtension

If your test relies on system properties you could set them and unset them in ‘before’ and ‘after’ lifecycle methods. In Junit5, setting system properties for all tests in a test case might look like this:

@BeforeAll
public static void setSystemProperties() {
    // set the system properties
    // ...
}

@AfterAll
public static void unsetSystemProperties() {
    // unset the system properties
    // and reinstate the original value for any property which was overwritten
    // ...
}

Setting system properties for a single test in a test case might look like this:

@Test
public void aTest() {
    // set the system properties
  
    try {
        // code-under-test
    } finally {
        // unset the system properties
        // and reinstate the original value for any property which was overwritten
    }
}

These approaches will work but they are verbose and brittle. The SystemPropertyExtension allows you to declare this behaviour by adding the @SystemProperty annotation to a test case or a test method. This annotation allows you to declare:

• name: the system property name
• value: The system property value

Examples

Class Level System Property

@SystemProperty(name = "x", value = "y")
public class MyTest {

    @Test
    public void aTest() {
        assertThat(System.getProperty("x"), is("y"));
    }
}  

Class Level System Properties

@SystemProperty(name = "x", value = "y")
@SystemProperty(name = "p", value = "q")
public class MyTest {

    @Test
    public void aTest() {
        assertThat(System.getProperty("x"), is("y"));
        assertThat(System.getProperty("p"), is("q"));
    }
}  

Method Level System Property

public class MyTest {

    @Test
    @SystemProperty(name = "x", value = "y")
    public void aTes() {
        assertThat(System.getProperty("x"), is("y"));
    }
}  

Method Level System Properties

public class MyTest {

    @Test
    @SystemProperty(name = "x", value = "y")
    @SystemProperty(name = "p", value = "q")
    public void aTes() {
        assertThat(System.getProperty("x"), is("y"));
        assertThat(System.getProperty("p"), is("q"));
    }
}