The standard command line use when testing go:
$ go test
Colors your test output according to your terminal configuration.
You can customize the colors for failing tests and passing tests via environment variables using the palette of your terminal.
The first color being for failures and the second one being for passes.
To find the colors in for example iTerm.app open the Preferences, your profile and the color tab.
Use the names for the colors in the environment variables
This article was lifted from my TIL collection