How to automatically execute a script before each JUnit test execution?

Question

My team is using JUnit to launch tests from eclipse.

Before executing these tests from eclipse, we have to specify the env variable LD_LIBRARY_PATH to load dependencies at run time. The correct value of LD_LIBRARY_PATH can change when one of my team's member commits a change in the project. We have a script which computes its correct value.

Today, we have two solutions to set the variable :

• run the script to get the value, and for each JUnit test we want to run, set it in Run Configurations window.
• write a script which sets the variable and launches eclipse.

First method is unproductive, and with second method, we have to restart eclipse each time we update the project.

A better solution would be to write a script which would set the variable and which would be called by eclipse each time a test is run.

Is there a way to call a script before each test with Eclipse ? Any other idea would be also greatly appreciated.

Answer 1

Following the idea of the SO queston How to run Unix shell script from Java code? you could execute a script before each test or each test class as follows

@Before // could also be @BeforeClass
public void setupEnvViaScript() throws IOException, InterruptedException {
  ProcessBuilder processBuilder = new ProcessBuilder("my-script.cmd", "arg-1", "arg-2");
  processBuilder.environment().put("JAVA_HOME", "value");
  processBuilder.environment().put("ENV_VAR", "value");

  processBuilder.directory(new File("d:/working/path/script/shall/be/executed/in"));
  Process process = processBuilder.start();

  int exitValue = process.waitFor();
  if (exitValue != 0) {
    // check for errors
    new BufferedInputStream(process.getErrorStream());
    throw new RuntimeException("execution of script failed!");
  }
}

This has some caveats

• this way it is platform depended
• the script and the path to it are hard-coded
• the working-directory is hard-coded

You could tackle this in several ways, like

• generate the script file on the fly before execution
• choose the execution path depended from some constraints