### Question:
KotlinLanguage extends AbstractLanguage { @Override public String[] getFileSuffixes() { String[] suffixes = configuration.getStringArray(KotlinPlugin.KOTLIN_FILE_SUFFIXES_KEY); if (suffixes == null || suffixes.length == 0) { suffixes = KotlinPlugin.KOTLIN_FILE_SUFFIXES_DEFAULT_VALUE.split(","); } return suffixes; } KotlinLanguage(Configuration configuration); @Override String[] getFileSuffixes();  }### Answer:
@Test public void test_suffixes_default() throws Exception { KotlinLanguage kotlinLanguage = new KotlinLanguage(new MapSettings().asConfig()); assertThat(kotlinLanguage.getFileSuffixes()).containsExactly(".kt"); }
@Test public void test_suffixes_empty() throws Exception { KotlinLanguage kotlinLanguage = new KotlinLanguage(new MapSettings().setProperty(KotlinPlugin.KOTLIN_FILE_SUFFIXES_KEY, "").asConfig()); assertThat(kotlinLanguage.getFileSuffixes()).containsExactly(".kt"); }
@Test public void test_suffixes_custom() throws Exception { KotlinLanguage kotlinLanguage = new KotlinLanguage(new MapSettings().setProperty(KotlinPlugin.KOTLIN_FILE_SUFFIXES_KEY, ".foo, .bar").asConfig()); assertThat(kotlinLanguage.getFileSuffixes()).containsExactly(".foo", ".bar"); }