Add color output for `mage -l` targets

[mirogta]

We now have ~30 mage build targets so the output from mage -l isn't very easy on eyes.

It would be nicer by coloring the build targets with some arbitrary color (cyan?) while leaving the description (comments on public mage funcs) in the default color.

Inspired by https://marmelab.com/blog/2016/02/29/auto-documented-makefile.html

[natefinch]

Hmm.. I'm not against this, but I always worry about terminal compatibility.

[mirogta]

Fair point... Is there a way to find out all people who are currently using or looking for using Mage, and then ask them if they use a color terminal?

Would it be compatible with your terminal?

[ghostsquad]

you could look at the TERM env var. If it's set to something like xterm-256color then enable by default. You can also provide options such as

--color
--no-color

to force one behavior regardless.

https://www.gnu.org/software/gettext/manual/html_node/The-TERM-variable.html

[mirogta]

@natefinch I have a working code and a test, but not quite ready yet for a PR, because...

I have a passing test, similar to the existing TestMageImportsList in import_test.go but instead of the expected string with a simple string which looks like this:

	actual := stdout.String()
	expected := `
Targets:
  buildSubdir        Builds stuff.
  ns:deploy          deploys stuff.
  root               
  zz:buildSubdir2    Builds stuff.
  zz:ns:deploy2*     deploys stuff.

* default target
`[1:]

	if actual != expected {
		t.Logf("expected: %q", expected)
		t.Logf("  actual: %q", actual)
		t.Fatalf("expected:\n%v\n\ngot:\n%v", expected, actual)
	}

... I have the expected string with the ANSI colored text:

	actual := stdout.String()
	expected := `
Targets:
  \033[36mbuildSubdir%s\033[0m        Builds stuff.
  \033[36mns:deploy%s\033[0m          deploys stuff.
  \033[36mroot%s\033[0m               
  \033[36mzz:buildSubdir2%s\033[0m    Builds stuff.
  \033[36mzz:ns:deploy2*%s\033[0m     deploys stuff.

* default target
`[1:]

	if actual != expected {
		t.Logf("expected: %q", expected)
		t.Logf("  actual: %q", actual)
		t.Fatalf("expected:\n%v\n\ngot:\n%v", expected, actual)
	}

So that's good. The code works OK and this test is passing and I check if the terminal supports colors and don't add the colors if it doesn't.

Now the challenge comes with the existing tests, which are obviously failing, because now every test case has colorized target names.

I've thought how do I "fix" the existing tests? I wanted to ensure that the tests would run irrespective of whether the terminal running the tests supports colors or not, e.g. your own terminal may support colors, but CI with a simple output may not.

My idea is to disable the color output, i.e. override the TERM variable, for every relevant test, and enable it explicitly only for my test which tests the colored output. This seems the most effective and least disruptive to existing tests. So only my test would look "ugly", but that's the price for a really nice colored output. I have to say I really do like how the targets stand out when I run mage -l.

Alternatively, I've thought I could have a function to strip out the colorized output from the actual code, so any other test but mine (which does need to test the colorized output) would have the assertion like this, so that the expected string can stay without the ANSI color codes:

	if removeAnsiColor(actual) != expected {

WDYT?

[natefinch]

That looks awesome. I think overriding TERM is fine.

[mirogta]

Great - see #301

@natefinch I don't seem to have permission to add reviwers to the PR. Can you please add yourself and review it? Thanks

[mirogta]

Closed by #301