I would suggest that you consult the web about the advantages and disadvantages which different testing libraries provide when it comes to testing MVVM apps. The MVVM is just a design pattern which helps developers separate the data (Model), from the UI (View). You can use any testing tool/strategy that you prefer and that would normally use for non-MVVM apps. Testing libraries usually have their own communities which can help you to get faster into the specifics of testing MVVM apps.
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