Error Testing annotator: Unexpected token <

Hi,
I'm extending LightPlatformCodeInsightFixtureTestCase to test my inspection,

        myFixture.configureByFiles(file);
this:        myFixture.checkHighlighting(false, false, true);  fails as my inspection indentifies the <error descr="error description...">f</error> as an unexpected part of the source.
I expected that the xml tags will be removed when the source is passed to the inspection, but it seems that it is not the case.
What am I missing here?
Thanks