Run unit tests only on Windows

Have you looked into assumptions? In the before method you can do this:

@Before
public void windowsOnly() {
    org.junit.Assume.assumeTrue(isWindows());
}

Documentation: http://junit.sourceforge.net/javadoc/org/junit/Assume.html

In Junit5, There are options for configuring or run the test for specific Operating System.

@EnabledOnOs({ LINUX, MAC })
void onLinuxOrMac() {

}

@DisabledOnOs(WINDOWS)
void notOnWindows() {
    // ...
}