```
.../tool/lib/colorize.rb:56:in `resolve_color': undefined method `gsub' for an instance of Symbol (NoMethodError)

    color.gsub(/\b[a-z][\w ]+/) do |n|
	 ^^^^^
	from .../tool/lib/colorize.rb:47:in `decorate'
	from .../tool/lib/test/unit.rb:1012:in `block in failed'
```

Not only:
```
$ ruby colorize.rb fail foo
```

Also:
```
$ ruby colorize.rb 'bright_blue;bold' foo
```

Support `NO_COLOR` (https://no-color.org/) to make parsing output easy.