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"));
    }

}

Answer 3

This can be achieved with https://github.com/webcompere/system-stubs/tree/master/system-stubs-jupiter

@ExtendWith(SystemStubsExtension.class)
class TestClass {

    @SystemStub
    private EnvironmentVariables environmentVariables =
        new EnvironmentVariables("demoVar", "val");

    @Test
    void test() {
        // can use the environment
        assertThat(System.getenv("demoVar")).isEqualTo("val");

        // can also change the environment
        environmentVariables.set("foo", "bar");

        // environment variables restored to previous state when
        // test ends
    }
}

Answer 4

Simple solution if you use Gradle, you can add following to your build.gradle

test {
  environment "ENV_VAR_NAME", "ENV_VAR_VALUE"
}

Link to Gradle doc: https://docs.gradle.org/current/dsl/org.gradle.api.tasks.testing.Test.html#org.gradle.api.tasks.testing.Test:environment

Answer 5

The common practice is to use System properties instead of environment variables. In this case you will run your java/maven/gradle command or whatever you use to run your tests with option -D demoVar="{your_value}". for maven goal:

 maven clean install -DdemoVar="test"

for java jar:

 java -jar xxx.jar -DdemoVar="test"

You will be able to get it from code with System.getProperty("demoVar") .

If you really need to use environment variable, use OS functionality. For linux:

demoVar="test" mvn clean install

For windows PowerShell:

$env:demoVar = 'test'; mvn clean install