@Test
    public void shouldOpenViaPropertiesFileConfig() throws IOException {
        final File scriptFile1 = TestSupport.generateTempFileFromResource(DefaultScriptCustomizerTest.class, "script-customizer-1.groovy", ".groovy");
        final File scriptFile2 = TestSupport.generateTempFileFromResource(DefaultScriptCustomizerTest.class, "script-customizer-2.groovy", ".groovy");
        final List<String> files = new ArrayList<>();
        files.add(Storage.toPath(scriptFile1));
        files.add(Storage.toPath(scriptFile2));
        final GremlinPlugin plugin = ScriptFileGremlinPlugin.build().files(files).create();

        assertThat(plugin.getCustomizers().isPresent(), is(true));
        assertThat(plugin.getCustomizers().get()[0], instanceOf(ScriptCustomizer.class));
        final ScriptCustomizer customizer = (ScriptCustomizer) plugin.getCustomizers().get()[0];
        final Collection<List<String>> linesInFiles = customizer.getScripts();
        final String scriptCombined = linesInFiles.stream().flatMap(Collection::stream).map(s -> s + System.lineSeparator()).reduce("", String::concat);
        assertEquals("x = 1 + 1" +  System.lineSeparator() +
                "y = 10 * x" +   System.lineSeparator() +
                "z = 1 + x + y" +  System.lineSeparator() +
                "l = g.V(z).out()" +  System.lineSeparator() +
                "        .group().by('name')" + System.lineSeparator(), scriptCombined);

    }
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/jsr223/ScriptFileGremlinPluginTest.java