Support --version in pub workspace

[natebosch]

Closes #2535

Add a check for the workspace_ref.json file in place of the
pubspec.lock file that exists for single package pub solutions.

When the workspace ref exists, follow it and read the
package_graph.json file from the workspace root.

[natebosch]

@jonasfj - do you have any concerns about the test running reading workspace_ref.json and package_graph.json files?

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[DanTup]

@natebosch I just noticed this in the comments:

/// This is a semantic version, optionally followed by a space and additional
/// data about its source.

The code just seems to return the version from the JSON. Do you know in what circumstances this has a space and additional data? (I think Dart-Code is just assuming it's always a valid version right now, and if this comment is still accurate I might need to update it).

[natebosch]

Do you know in what circumstances this has a space and additional data?

The existing code path that reads from pubspec.lock can return extra data.

test/pkgs/test_core/lib/src/runner/version.dart

Lines 77 to 95 in cd8e74d

	case 'git':
	var version = package['version'];
	if (version is! String) return null;
	var description = package['description'];
	if (description is! Map) return null;
	var ref = description['resolved-ref'];
	if (ref is! String) return null;
	return '$version (${ref.substring(0, 7)})';
	case 'path':
	var version = package['version'];
	if (version is! String) return null;
	var description = package['description'];
	if (description is! Map) return null;
	var path = description['path'];
	if (path is! String) return null;
	return '$version (from $path)';

I didn't replicate it mostly because I don't expect it to be worth the effort. Barely anyone uses a git or path dependency on the test runner. I think it's safe enough for dart-code to assume it will only ever see a semver version there.

If removing it doesn't break much on CI we could also drop that behavior entirely.

[natebosch]

If removing it doesn't break much on CI we could also drop that behavior entirely.

Checking the feasibility in #2539

[natebosch]

@sigurdm do you have any concerns about this usage? Are workspace_ref.json and package_graph.json stable enough to rely on this way?

[DanTup]

Barely anyone uses a git or path dependency on the test runner. I think it's safe enough for dart-code to assume it will only ever see a semver version there.

Ah, thanks for the info. I'll leave Dart-Code as it is then. We do handle when we can't parse a version from the output and it sounds like you might remove this anyway. If it can't be removed and it turns out to be a problem, I'll just trim after the first space.

[sigurdm]

@jonasfj - do you have any concerns about the test running reading workspace_ref.json and package_graph.json files?

I don't think reading workspace_ref is any big issue. Flutter tools already relies on the file being there, so it is probably not going anywhere. But I think it would be easier to use https://api.dart.dev/dart-isolate/Isolate/packageConfigSync.html to find the package config, and then find package_graph.json next to that.

You can rely on the package_graph always being present, so if you are ok with just the version number (no information about the source), you should be able to leave out the code reading pubspec.lock

[sigurdm]

And, alternatively, if you want to always read the pubspec.lock file, it will always be present in the parent directory of the package_config.json file, then you don't need to read package_graph.json.