Add "TerminalWriter.write_source" to write highlighted source code

[nicoddemus]

How this looks like in pytest:

[blueyed]

Nice! I've thought about adding it to pytest myself.
I think given how thin the wrapper is there is not much gain in adding to pylib - it should rather go into pytest directly AFAICS.
(there's the base for extending it in _pytest._io already.

[blueyed]

There's also 256-color and true color support.. https://github.com/pygments/pygments/blob/master/pygments/formatters/terminal256.py

Something like this could be used for auto-detect, but it should be made configurable probably.

        pygments_formatter_class = "pygments.formatters.TerminalTrueColorFormatter"
        pygments_formatter_kwargs = {"bg": "light", "style": "solarized-light"}

(from my pdbpp config)

[nicoddemus]

Closing in favor of pytest-dev/pytest#6658