### Question:
PropertiesBackendConfiguration extends BaseConfiguration implements ConfigurationProperties { @Override public Capabilities getCapabilities() { String capabilities = getProperty("capabilities"); if (isValidProperty(capabilities)) { return capabilitiesRetriever.getCapabilitiesProperty(capabilities, getGlobalConfiguration()); } return null; } PropertiesBackendConfiguration(PropertiesBackend propertiesReader);   PropertiesBackendConfiguration(PropertiesBackend propertiesReader, String... prefixes); @Override Class<? extends ConfigurationFactory> getConfigurationFactory(); @Override Class<? extends ConfigurationProperties> getConfigurationDefaults(); @Override String getWebDriver(); @Override String getRemoteUrl(); @Override Capabilities getCapabilities(); @Override DriverLifecycle getDriverLifecycle(); @Override Long getBrowserTimeout(); @Override Integer getBrowserTimeoutRetries(); @Override Boolean getDeleteCookies(); @Override String getBaseUrl(); @Override Boolean getEventsEnabled(); @Override Long getPageLoadTimeout(); @Override Long getImplicitlyWait(); @Override Long getScriptTimeout(); @Override Long getAwaitAtMost(); @Override Long getAwaitPollingEvery(); @Override String getScreenshotPath(); @Override String getHtmlDumpPath(); @Override TriggerMode getScreenshotMode(); @Override TriggerMode getHtmlDumpMode(); @Override String getCustomProperty(String propertyName);  }### Answer:
@Test public void capabilitiesURL() { URL capabilitiesURL = getClass().getResource("/org/fluentlenium/configuration/capabilities.json"); DesiredCapabilities capabilitiesJSEnabled = new DesiredCapabilities(); capabilitiesJSEnabled.setJavascriptEnabled(true); when(retriever.getCapabilitiesProperty(capabilitiesURL.toString(), null)).thenReturn(capabilitiesJSEnabled); URL capabilitiesFalseURL = getClass().getResource("/org/fluentlenium/configuration/capabilities-false.json"); DesiredCapabilities capabilitiesJSDisabled = new DesiredCapabilities(); when(retriever.getCapabilitiesProperty(capabilitiesFalseURL.toString(), null)).thenReturn(capabilitiesJSDisabled); assertThat(getConfiguration().getCapabilities()).isNull(); mockProperty("capabilities", capabilitiesURL.toString()); assertThat(getConfiguration().getCapabilities()).isEqualTo(capabilitiesJSEnabled); mockProperty("capabilities", capabilitiesFalseURL.toString()); assertThat(getConfiguration().getCapabilities()).isSameAs(capabilitiesJSDisabled); }