feat(coverage): add "--output" flag

[VishnuJin]

This pr adds output arg to deno coverage to pipe the stdout to the given file, just like deno bundle

fixes #13236

[VishnuJin]

@bartlomieju
I believe deno bundle accepts only one source file and hence the second arg can be interpreted as out_file but in case of deno coverage it accepts multiple files, how can we assume that the last arg is the out_file argument unless explicitly specified with out_file ?

[bartlomieju]

@bartlomieju I believe deno bundle accepts only one source file and hence the second arg can be interpreted as out_file but in case of deno coverage it accepts multiple files, how can we assume that the last arg is the out_file argument unless explicitly specified with out_file ?

Good point. Let's go with explicit --output argument.

[VishnuJin]

@bartlomieju apologies for the delay!! I have resumed working on this and can share progress soon..

[VishnuJin]

@bartlomieju I noticed js_unit_tests tests infastci macOS fail couple of time although it passed in my local runs

[bartlomieju]

@VishnuJin no worries, seems like a flake.

[VishnuJin]

@bartlomieju awaiting for you review 🙂

[bartlomieju]

@VishnuJin I just tested this PR and it works nicely, we should land it for 1.19. I found one quirk though, please see comment below

[bartlomieju]

This arg should require --lcov arg to be present, otherwise I can do:

deno coverage --output=cov.lcov cov/

which makes no sense, since it means to print test report to stdout

[VishnuJin]

yeah, I somehow missed requires method in clap and implemented the following which is obviously not so good, and I will change this now

deno/cli/tools/coverage/mod.rs

Lines 618 to 630 in eff2796

	// only create file for if '--lcov' flag is passed
	let mut out_mode: Option<PathBuf> = None;
	if coverage_flags.lcov {
	out_mode = match coverage_flags.output {
	Some(ref path) => match File::create(path) {
	Ok(_) => Some(PathBuf::from(path)),
	Err(e) => {
	return Err(anyhow!("Failed to create output file: {}", e));
	}
	},
	None => None,
	};
	}

[VishnuJin]

@bartlomieju thanks for the hint,

deno/cli/flags.rs

Lines 736 to 738 in c4356c0

	.arg(Arg::new("output")
	.requires("lcov")
	.long("output")

[VishnuJin]

@bartlomieju should I do something here ?

[bartlomieju]

@VishnuJin no, I made a mistake rebasing your PR, need to land other PR first before it's fixed.

[bartlomieju]

LGTM, thank you @VishnuJin