Set System Properties or Environment Variables Before Property Placeholder with SpringJunit4ClassRunner

Question

I have a main app-context.xml that defines a property placeholder with two locations: default properties file and an optional override file:

<context:property-placeholder
        location="classpath:config.properties,${configOverride}"
        ignore-resource-not-found="true" />

The optional override location allows specifying another properties file (e.g. "-DconfigOverride=file:/home/app/config.properties") with only the properties that should be overridden.

For my unit tests, I'm using a test context that imports app-context.xml:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:test-context.xml"})
public class UserServiceTest {
    ...
}

How can I set system properties or environment variables within the application before the application context is loaded? I would like to achieve the same effect as setting "-DconfigOverride=classpath:testConfig.properties" across all test classes without having to specify a command line arg, if possible.

Answer 1

One other alternative is setting the environment property in a @BeforeClass annotated method, which will be invoked before the Context Configuration happens.

@BeforeClass
public static void setSystemProps() {
    System.setProperty("configOverride", "yourVal");
}

Answer 2

Thinking of ,

1. Extending SpringJUnit4ClassRunner and setting the system property configOverride in its constructor/initialization block
2. Then passing ExtendedSpringJUnit4ClassRunner to @RunWith