how to set the environment variables in junit 5 for test case

Question

i am working on Junit5 . My java code uses the System.getenv("demoVar") to access environment variable . so how do i set up this environment variable in the jUnit5 test class , so that my code can access the value of this environment variable during the test.

Answer 1

From this other SO answer https://stackoverflow.com/a/59635733/2185719:

There is JUnit Pioneer, a "JUnit 5 extension pack".

jUnit Pioneer offers an annotation that sets environment variables for a test. For example:

@Test
@SetEnvironmentVariable(key = "PATH", value = "")
void testPath_isEmpty() {
    assertThat(System.getenv("PATH")).isEmpty();
}

Answer 2

You can't within the actual java process because these environmental values using getenv are immutable.

One way would be to start another vm or another process where you could introduce your new environment value.

Another way would be to switch to System.getProperty, but be sure you understand the differences.

https://www.baeldung.com/java-system-get-property-vs-system-getenv

Here is a little testcode:

public class EnvironmentVarsTest {
    private static int counter = 0;

    @BeforeEach
    public void setUp() {
        counter = counter + 1;
        System.setProperty("simple_test_env_property", String.valueOf(counter));
    }

    @Test
    public void testFirst() {
        printOutValues();
    }

    @Test
    public void testSecond() {
        printOutValues();
    }

    private void printOutValues() {
        System.out.println("--------------------");
        System.out.println("val=" + counter);
        System.out.println("envval=" + System.getProperty("simple_test_env_property"));
    }

}