System.setProperty("test_var", "underscore");
        value = "${test_var}";
        assertEquals("underscore", ResourceUtil.resolve(value));

        // Clean up test properties
        System.clearProperty("var1");
        System.clearProperty("var2");
        System.clearProperty("special");
        System.clearProperty("123");
        System.clearProperty("test_var");
    }

        boolean[] pbCallExecuted = { false };

        Consumer<ProcessBuilder> pbCall = pb -> {
            pb.redirectErrorStream(true);
            pb.environment().put("TEST_VAR", "test_value");
            pbCallExecuted[0] = true;
        };

        try {
            JobProcess jobProcess = processHelper.startProcess(sessionId, cmdList, pbCall);
            assertNotNull(jobProcess);

        assertEquals(Locale.ROOT, fessConfig.getQueryLocaleFromName(""));
        assertEquals(Locale.ROOT, fessConfig.getQueryLocaleFromName("ja"));
        assertEquals(Locale.JAPANESE, fessConfig.getQueryLocaleFromName("test_ja"));
        assertEquals(Locale.CHINESE, fessConfig.getQueryLocaleFromName("test_zh"));
        assertEquals(Locale.SIMPLIFIED_CHINESE, fessConfig.getQueryLocaleFromName("test_zh_cn"));

        PythonJob result = pythonJob.filename("test.py");

        assertSame(pythonJob, result);
        assertEquals("test.py", pythonJob.filename);
    }

    // Test single argument addition
    public void test_arg() {
        assertTrue(pythonJob.argList.isEmpty());

        PythonJob result = pythonJob.arg("arg1");

        assertSame(pythonJob, result);
        assertEquals(1, pythonJob.argList.size());