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Take a look at the latest v3 branch. There are lots of example tests. I suggest you would want unit tests for your custom widgets, and integration tests for your end-to-end logic.
The source itself includes integration tests which load data from a source file (e.g. Excel), and process it via import. You could adapt this to read from a source file, do your import, and then read objects back directly from the db to ensure that they are in the correct state.
Ensure you test with the v3 beta as this will become the latest version of the library in the next month or so.
Source:stackexchange.com