I was viewing a commit that held some changes to a large JSON file holding test data.
The diff looks reasonable at first glance:
However, when looking at it, I realised that some crucial data was omitted (the input data for the test). Only on much closer inspection did I realise that there are 443 missing lines (from line 73247 to line 72802) with no visual indication at all of that fact!
This means that although it looks like it’s possible to review the changes in the PR, it’s actually not, because crucial context is silently omitted.