This will walk you through setting up a test coverage report on coveralls.io which will be updated every time a new build happens on drone.io (a continuous integration server similar to TavisCI).

I’m going to use the couchbaselabs/sg-replicate repo as an example, since it currently does not have any test coverage statistics. The goal is to end up with a badge in the README that points to a test coverage report hosted on coveralls.io.

Clone the repo

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$ git clone https://github.com/couchbaselabs/sg-replicate.git
$ cd sg-replicate

Test coverage command line stats

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$ go test -cover
go tool: no such tool "cover"; to install:
  go get golang.org/x/tools/cmd/cover

Try again:

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$ go get golang.org/x/tools/cmd/cover && go test -cover
PASS
coverage: 69.4% of statements
ok    github.com/couchbaselabs/sg-replicate   0.156s

Ouch, 69.4% is barely a C-. (if you round up!)

Coverage breakdown

Text report:

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$ go test -coverprofile=coverage.out 
$ go tool cover -func=coverage.out
github.com/couchbaselabs/sg-replicate/attachment.go:15:           NewAttachment           84.6%
github.com/couchbaselabs/sg-replicate/changes_feed_parameters.go:20:  NewChangesFeedParams        100.0%
github.com/couchbaselabs/sg-replicate/changes_feed_parameters.go:30:  FeedType            100.0%
github.com/couchbaselabs/sg-replicate/changes_feed_parameters.go:34:  Limit               100.0%

HTML report:

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$ go test -coverprofile=coverage.out 
$ go tool cover -html=coverage.out

This should open up the following report in your default browser:

Coveralls.io setup

• Login to coveralls.io
• Create a new repo
• Get the repo token from the SET UP COVERALLS section

At this point, your empty coveralls repo will look something like this:

Configure Drone.io + Goveralls

If you have not already done so, setup a drone.io build for your repo.

On the drone.io Settings page, make the following changes:

Environment Variables

In the Environment Variables section of the web ui, add:

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COVERALLS_TOKEN=<coveralls_repo_token>

Commands

In the commands section, you can replace your existing go test call with:

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go get github.com/axw/gocov/gocov
go get github.com/mattn/goveralls
goveralls -service drone.io -repotoken $COVERALLS_TOKEN

Here’s what it should look like:

Kick off a build

Go to the drone.io project page for your repo, and hit Build Now

At the bottom of the build output, you should see:

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Job #1.1
https://coveralls.io/jobs/5189501

If you follow the link, you should see something like:

Looks like we just went from a C- to a B! I have no idea why the coverage improved, but I’ll take it.

Add a badge, call it a day

On the coveralls.io project page for your repo, you should see a button near the top called Badge URLS. Click and copy/paste the markdown, which should look something like this:

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[![Coverage Status](https://coveralls.io/repos/couchbaselabs/sg-replicate/badge.svg?branch=master)](https://coveralls.io/r/couchbaselabs/sg-replicate?branch=master)

And add it to your project’s README.

References

• https://blog.golang.org/cover
• https://github.com/mattn/goveralls