make coverage threshold show lines missing coverage

[grosser]

Running with --threshold can fail and then shows "expected 100% got 98%", which then means I have to get out the coverage data and figure out where the problem is.
Ideally it would show missing coverage:\nfoo.rego:12
this could be overwhelming when lots of things are uncovered, so it should be opt in or only show the first N lines with missing coverage.

/cc contributors from threshold #1029 @EliuX @tsandall @flavio @srenatus

[tsandall]

This would be a nice enhancement and is a good area for contribution. At a high-level, I'd expect we would want to:

1. Update opa test so that the "pretty" format reports text instead of JSON
2. Update the "pretty" output mode to include the missing lines (sorted by file/line #)

I'm not too worried about the # of missing lines since I would expect most policies to be completely covered (and in my experience this is often the case.)

[Syn3rman]

Hey @tsandall,

Can I take this up if it is available?
From my understanding, implementing a PrettyCoverageReporter similar to the JSONCoverageReporter should suffice, right?

Also, does the following output format work?

$ opa test -c --threshold 80 ex_tests/ -v

ex_tests/example.rego 57.15%
--------------------------------------------------------------------------------
Not covered: Line 3 to 5

Code coverage threshold not met: got 76.90 instead of 80.00

$ opa test -c ex_tests/ -v
Coverage: 76.9%

ex_tests/example_test.rego 100%
--------------------------------------------------------------------------------
Covered: Line 3 to 4
Covered: Line 7 to 8
Covered: Line 11 to 12

ex_tests/example.rego 57.15%
--------------------------------------------------------------------------------
Covered: Line 8 to 8
Covered: Line 10 to 12
Not covered: Line 3 to 5

[grosser]

• showing covered lines is redundant
• showing full file + number makes it easy to copy and navigate to in editor

missing coverage:
foo.rego:123-125
foo.rego:127

[grosser]

thx, that looks perfect!