Add pp plot test
It looks like !1077 (merged) had a bug that made it through the unit tests but was flagged by the integration tests. I've fixed the bug and added some unit tests for the pp-plot function.
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It looks like !1077 (merged) had a bug that made it through the unit tests but was flagged by the integration tests. I've fixed the bug and added some unit tests for the pp-plot function.