pretty option is ignored in terminal

[elevatebart]

Expected Behavior

When I specify pretty: false I expect the errors to respect that.
This is particularly useful if I am developing a tool that uses ts-node and I need to handle 3rd party potentially faulty code.

Actual Behavior

Because of this line, when I use a terminal as the main output for my tool, pretty is ignored:

ts-node/src/index.ts

Lines 628 to 630 in e8a4d76

	const formatDiagnostics =
	process.stdout.isTTY || options.pretty
	? ts.formatDiagnosticsWithColorAndContext || ts.formatDiagnostics

Steps to reproduce the problem

Run ts-node on a faulty codebase with --pretty false option.
Errors are still styled with terminal only decoration.

Minimal reproduction

TypeStrong/ts-node-repros#16

Specifications

ts-node v8.3.0
node v14.17.0
compiler v4.3.5

tsconfig.json

{
  "compilerOptions":{
    "pretty": false
  }
}

• Operating system and version: MacOS - Big Sur

[cspotcode]

Sounds like we want 3x states for the pretty flag: true forces it enabled, false forces it disabled, and undefined (not specified anywhere) allows the default to be determined based on isTTY. Does that sound reasonable?

Are you able to send a pull request for this?

[cspotcode]

The docs will need to be updated to match, as well.
https://typestrong.org/ts-node/docs/options/#diagnostics

[elevatebart]

I'll whip up a PR right now.
I don't see where this is tested though.
Do you know if it is tested at all?

[cspotcode]

I replied to the PR before seeing this comment.

It might be untested. Most of the tests invoke the CLI, which isn't the fastest but is simple to think about. Feel free to write a couple tests that do that.