props.put(ContextualDiffProvider.PROP_UNCHANGED_CONTEXT_LIMIT, contextLimit);
diff.initialize(null, props);
PropertyConfigurator.configure(props);
TestEngine engine = new TestEngine(props);
WikiContext ctx = new WikiContext( engine, new WikiPage(engine,"Dummy") );
String actualDiff = diff.makeDiffHtml( ctx, oldText, newText);
assertEquals(expectedDiff, actualDiff);