go-coverage-enforcer

Go test coverage enforcer

This command-line tool can be used in conjunction with Go's built-in coverage profiling to provide CI enforcement of coverage goals.

Unlike other tools for a similar purpose, go-coverage-enforcer does not generate the coverage profile itself, does not instrument the code, and has no opinions about any particular patterns in the code. It is simply a post-processing step after a coverage profile has already been generated with go test.

Usage

go install github.com/launchdarkly-labs/go-coverage-enforcer

go test . -coverprofile coverage.out
go-coverage-enforcer coverage.out

The working directory should be the base directory of the package that is being tested.

The command writes results to standard output, and returns exit code 1 if any problems were found, 0 otherwise.

Options

-package IMPORTPATH

Specifies the import path of the current package that is being tested.

If you don't specify this, go-coverage-enforcer will try to determine the package by looking for a go.mod file in the current directory. As a fallback, it will check whether the current directory is a Git checkout and will try to determine the import path from the Git URL.

-packagestats, -filestats

Causes the output to include coverage statistics per package and/or per file. A number like "140/200" means that go test counted 200 statements in that package or file (not counting any files or code ranges that were excluded with -skipfiles or -skipcode), and that 140 of those statements were covered.

-showcode

Causes the output to include the source code of each uncovered block.

With -showcode:

Uncovered blocks detected:

somepackage/some_file.go 133-135
133>        if n == 0 {
134>            return nil
135>        }

Without -showcode:

Uncovered blocks detected:

somepackage/some_file.go 133-135

-skipfiles PATTERN

If provided, this must be a valid regular expression. Any files whose relative path matches this expression will be skipped when analyzing the coverage profile.

-skipcode PATTERN

If provided, this must be a valid regular expression. Uncovered code blocks containing any line matching this expression will be skipped.

This is a way to add explicit overrides of coverage checking in code paths where test coverage is impossible. For instance, specifying `-skipcode "// NOCOVER" would allow usage like this:

    if err != nil {
        return err // NOCOVER: there is no way to cause this error in unit tests
    }

This only affects the processing done by go-coverage-enforcer-- not the original coverage report generated by go test.

-outprofile FILEPATH

This causes go-coverage-enforcer to write the profile data to the specified path, in the same format that was generated by go test, after removing any code blocks that were skipped due to -skipfiles or -skipcode.

You can then run go cover on the filtered file to generate coverage reports that reflect this filtering. For instance, if you run go cover -html=FILEPATH to view the report as a web page, skipped files will not appear and skipped code blocks will appear in gray rather than red or green, and coverage percentages will be calculated as if the skipped files and blocks did not exist.