How to have Go coverage HTML with light background?

Question

Consider the following command:

go tool cover -html=coverage.out

Is there a way to make the resulting HTML dark on light (rather than the default light characters on dark background)?

I did not find anything about this neither in the documentation nor in the help pages referenced therein (go tool cover --help and go help testflag)

Answer 1

Not with the built-in tool. There's nothing preventing you from piping the output through some script to change CSS colors, though, or to reference an external CSS file that sets the colors you prefer.

Answer 2

As mentioned by @Flimzy, this is not supported with the built-in tool.

Though, looking at the coverage.html file output by the cover tool.

You can do something like this:

go tool cover -o coverage.html -html=coverage.out; sed -i 's/black/whitesmoke/g' coverage.html; sensible-browser coverage.html

which will write the output to coverage.html using the -o flag and then use sed to change occurrences of black to whitesmoke. It will then use your default browser to open the file.

Note #1: Obviously, this will not work once the tool is updated not to output black color background. Though, if this changes, there is probably a lot better support for different color schemes.

Note #2: If you use heat maps -covermode=count, the light green might look awkward on the smokewhite color. Feel free to try different color accents though.