hpc-threshold

hpc-threshold ensures the code coverage of your Haskell project is above configured thresholds. This program is meant to be used within a CI pipeline, in which the build will fail if the code coverage falls below the configured thresholds.

The program reads a configuration file named .hpc-threshold and parse Haskell Program Coverage (HPC) text from stdin. The program outputs a report and will terminate with exit code 1 if the coverage falls below the configured threshold, and exit code 0 otherwise.

User Guide

Install the program by using stack

stack install hpc-threshold

Then, create a configuration file named .hpc-threshold:

[ Threshold 
    { thresholdName = "Expressions used"
    , thresholdRegex = "(\\d+)% expressions used"
    , thresholdValue = 80.0
    }
, Threshold 
    { thresholdName = "Boolean coverage"
    , thresholdRegex = "(\\d+)% boolean coverage"
    , thresholdValue = 80.0
    }
, Threshold 
    { thresholdName = "Alternatives used"
    , thresholdRegex = "(\\d+)% alternatives used"
    , thresholdValue = 80.0
    }
, Threshold 
    { thresholdName = "Local declarations used"
    , thresholdRegex = "(\\d+)% local declarations used"
    , thresholdValue = 80.0
    }
, Threshold 
    { thresholdName = "Top-level declarations used"
    , thresholdRegex = "(\\d+)% top-level declarations used"
    , thresholdValue = 80.0
    }
]

• thresholdRegex is the regex to be used for extracting the coverage from HPC report. There should be one (\\d+) in the regex.
• thresholdValue is the threshold for the code coverage.
• thresholdName will be used for the threshold report.

Then, build the coverage report:

stack test --coverage

Then, generate a text report and feed that into hpc-threshold:

stack hpc report --all 2>&1 | hpc-threshold

The stderr -> stdout redirection is necessary there because stack hpc report outputs the result in stderr, but we want to pipe that into hpc-threshold.

Then, you’ll get an output similar to the following:

Code coverage threshold check: FAIL
· Expressions used: 67.0% (< 80.0%)
· Boolean coverage: 14.0% (< 80.0%)
· Alternatives used: 42.0% (< 80.0%)
✓ Local declarations used: 88.0% (≥ 80.0%)
✓ Top-level declarations used: 80.0% (≥ 80.0%)

If we check the exit code of the last process, we’ll get 1 since some code coverage areas are below the configured threshold:

$ echo $?
1

For successful scenario, the output that you’ll get is as follows:

Code coverage threshold check: PASS
✓ Expressions used: 67.0% (≥ 60.0%)
✓ Boolean coverage: 14.0% (≥ 10.0%)
✓ Alternatives used: 42.0% (≥ 40.0%)
✓ Local declarations used: 88.0% (≥ 80.0%)
✓ Top-level declarations used: 80.0% (≥ 80.0%)

And the exit code is 0:

$ echo $?
0

Developer Guide

See .travis.yml, under scripts section to see how to build the application