### Question:
ThymeleafTemplateCollector implements TemplateEngine { @Override public String extension() { return THYMELEAF_TEMPLATE_EXTENSION; } ThymeleafTemplateCollector(BundleContext context); @Invalidate void stop(); void updatedTemplate(Bundle bundle, File templateFile); void deleteTemplate(File templateFile); ThymeLeafTemplateImplementation addTemplate(Bundle bundle, URL templateURL); @Validate synchronized void configure(); @Bind(optional = true, aggregate = true) synchronized void bindDialect(IDialect dialect); @Unbind synchronized void unbindDialect(IDialect dialect); @Override Collection<Template> getTemplates(); @Override String name(); @Override String extension(); ThymeLeafTemplateImplementation getTemplateByResourceName(String resourceName); synchronized void updatedTemplate(); void deleteTemplate(ThymeLeafTemplateImplementation template); static final String THYMELEAF_TEMPLATE_EXTENSION; static final String THYMELEAF_ENGINE_NAME; }### Answer:
@Test public void testExtension() throws Exception { BundleContext ctxt = mock(BundleContext.class); ThymeleafTemplateCollector collector = new ThymeleafTemplateCollector(ctxt); assertThat(collector.extension()).isEqualToIgnoringCase("thl.html"); }