Wonderful!
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<br>Just one thing - it could be cool if you just incorporated the expected exception into the usual Test component with a nullable value in the properties pane. A non null value of type System.Type that derives from System.Exception would put an ExpectedExceptionAttribute on the test case. I don't see why there has to be a new component just for that feature. :/
<br>This would help remove multiple types of tests from your list.
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<br>Also, I'm not sure of this, but I think you can use different icons for components (rather than that yellow cogwheel). Could be nice. :)
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<br>Just my .02$. :)

&gt;it could be cool if you just incorporated the expected exception into the usual Test component with a nullable value
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<br>That makes sense. I'll refactor. I'm also adding PerformanceCounter to the fixture component so that you can add counters and use the designer to set them up :)
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<br>&gt;but I think you can use different icons for components
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<br>ToolBarImageAttribute

Update: ExpectedExceptionTestCaseComponent has been merged into TestCaseComponent...