### Question:
ConfigurationProviderImpl implements ConfigurationProvider { @Override public void saveFormat(DateFormat format) { saveFormats(New.list(format)); } ConfigurationProviderImpl(PreferencesRegistry prefsRegistry); @Override synchronized DateFormatsConfig getDateFormats(); @Override void saveFormat(DateFormat format); @Override List<String> getExcludeColumns(); @Override synchronized void saveFormats(Collection<DateFormat> formats);  }### Answer:
@Test public void testSaveDateFormat() { EasyMockSupport support = new EasyMockSupport(); DateFormat existingFormat = new DateFormat(); existingFormat.setSdf("existing"); ourConfig.addFormat(existingFormat); DateFormat format = new DateFormat(); PreferencesRegistry prefsRegistry = createSaveRegistry(support, format); support.replayAll(); ConfigurationProviderImpl provider = new ConfigurationProviderImpl(prefsRegistry); provider.saveFormat(format); format.setSdf("existing"); provider.saveFormat(format); format.setSdf("save"); provider.saveFormat(format); support.verifyAll(); }