Be smarter about “dumb” terminals

[Alhadis]

When terminals are declared as "dumb", it means the author doesn't want/expect anything other than plain-text output. There's usually a damn good reason for this — we should treat TERM=dumb as meaning FORCE_COLOR=0, instead of imagining this.

Fixes: chalk/supports-color#88
Related: mochajs/mocha#1304, emacs.stackexchange.com/q/27218

Emacs compile command — Before and after:

@plroebuck As you can see, it seems some changes are still required elsewhere to clean up the stack-trace highlighting.

This fix has the unfortunate effect of impacting Emacs commands which do colourise output directly, such as mocha.el's (mocha-test-project) command:

mocha.el — Before and after:

Authors can always fix this by forcing colours in their environments, though, so this shouldn't be a problem in the long-run.

[Qix-]

Yeah this looks fine to me. Could you add a test that would fail under previous scenarios?

[Alhadis]

What sort of test are we looking at? Did you want me to write a Lisp script to automate Emacs to run a compiled build with mocha, and do it again with the elevated priority of the TERM=dumb variable?

[Qix-]

Less about Emacs, more just the fact that TERM_PROGRAM was being honored at a higher priority than TERM=dumb.

[Alhadis]

Ah good, because using Emacs as a general-purpose language interpreter tends to get bulky and messy quick... 😟

[Alhadis]

Is this good enough??

test('disables colours entirely if `TERM=dumb` is in env', t => {
	process.stdout.isTTY = true;
	process.stderr.isTTY = true;
	process.env.TERM = 'dumb';
	const result = importFresh('.');
	t.truthy(result.stdout);
	t.truthy(result.stderr);
	t.is(result.stdout.level, 1);
	t.is(result.stdout.level, 1);
});

test('it allows `TERM=dumb` to be overridden by `FORCE_COLOR` in env', t => {
	process.stdout.isTTY = false;
	process.env.TERM = 'dumb';
	process.env.FORCE_COLOR = true;
	const result = importFresh('.');
	t.truthy(result.stdout);
	t.is(result.stdout.level, 1);
});

I figured out what the spurious highlighting was before; some auto-reformatter thing was modifying code while I was saving changes, and I didn't even notice . I'm assuming that's that xo thing? D:

This was the newest error I just choked on. D:

 disables colours entirely if `TERM=dumb` is in env

  /Users/john/Forks/supports-color/test.js:19

   18:   const result = importFresh('.');
   19:   t.truthy(result.stdout);        
   20:   t.truthy(result.stderr);        

  Value is not truthy:

  false

  result.stdout
  => false

Look, I don't know what you're using to run your tests, or why importFresh() exists, or what half of these flags and levels do or mean. But I really don't have the time or patience for this, I'm sorry. Can I leave it to you to add a test for this, please?

[Qix-]

One needs to check the TERM_PROGRAM as well.

[plroebuck]

I'd fix "tests.js" myself, but don't see "command line instructions" in the merge box to checkout the commit.

Nvm. Made my own...

[Alhadis]

Closing in favour of #89

[Qix-]

Psst.. this is #89 ;) think you mean #90 haha

[Alhadis]

LOL, yes. My bad.