opa test diff result

[ashutosh-narkar]

opa test has the --show-failure-line flag that shows the line number of the test failure. It would be helpful for debugging if the opa test command printed a diff between the actual and expected values that resulted in the test failure.

[tsandall]

One option would be to identify failed expressions from test rules in the trace and then plug them to show the actual vs. expected values. This would help quite a bit in terms of debugging failed tests.

[tsandall]

Closing this in favor of #2546.