In a previous post I blogged about the cover tool coming in Go 1.2 and a bash helper function I use to make the tool a little easier to use.

Since then I’ve extended these helpers so I wanted to blog about the improvements.

Passing arguments to the testing tool

cover () {
  t=$(tempfile)
  go test $COVERFLAGS -coverprofile=$t $@ && go tool cover -func=$t && unlink $t
}

The first improvement is to be able to pass arguments to go test, this is done by setting COVERFLAGS before invoking the cover helper.

As an example, I have defined a flag in the sftp package tests that allow me to switch the integration tests on and off.

% cover github.com/pkg/sftp
PASS
coverage: 20.4% of statements
...
 % COVERFLAGS=-integration cover github.com/pkg/sftp 
PASS
coverage: 69.2% of statements
...

Viewing coverage details

The cover in its default mode will give you a percentage coverage on a per function basis, but it doesn’t tell you which parts of the function are uncovered.

cover-web() {
  t=$(tempfile)
  go test $COVERFLAGS -coverprofile=$t $@ && go tool cover -html=$t && unlink $t
}

To explore the coverage report in detail, this helper runs the cover tool then opens a web browser with a html version of the coverage report.

Enjoy!