making desktop-client tests independent (#765)

Tests cases should be independent. You should be able to run them in
whatever order you want. And they should still pass.

Currently this is not the case. The order of the tests is very important
due to the "pseudo" randomization algorithm.

This PR makes the mock data IDs truly unique thus better exposing the
issue in our tests. Also this PR fixes the dependency issues thus making
each test case truly independent.

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Co-authored-by: Jed Fox <git@jedfox.com>