Support --version in pub workspace

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.

Author: natebosch

pkgs/test_core/CHANGELOG.md

@@ -3,6 +3,7 @@
 * Restrict to latest version of analyzer package.
 * Require Dart 3.7
 * Add `--coverage-path` and `--branch-coverage` options to `dart test`.
+* Add support for reading test package version within pub workspaces.
 
 ## 0.6.12
 

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

@@ -2,60 +2,99 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'dart:convert';
 import 'dart:io';
 
+import 'package:collection/collection.dart';
+import 'package:path/path.dart' as p;
 import 'package:yaml/yaml.dart';
 
 /// The version number of the test runner, or `null` if it couldn't be loaded.
 ///
 /// This is a semantic version, optionally followed by a space and additional
 /// data about its source.
-final String? testVersion =
-    (() {
-      dynamic lockfile;
-      try {
-        lockfile = loadYaml(File('pubspec.lock').readAsStringSync());
-      } on FormatException catch (_) {
-        return null;
-      } on IOException catch (_) {
-        return null;
-      }
-
-      if (lockfile is! Map) return null;
-      var packages = lockfile['packages'];
-      if (packages is! Map) return null;
-      var package = packages['test'];
-      if (package is! Map) return null;
-
-      var source = package['source'];
-      if (source is! String) return null;
-
-      switch (source) {
-        case 'hosted':
-          var version = package['version'];
-          return (version is String) ? version : null;
-
-        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)';
-
-        default:
-          return null;
-      }
-    })();
+final String? testVersion = _readWorkspaceRef() ?? _readPubspecLock();
+
+String? _readWorkspaceRef() {
+  try {
+    final workspaceRefPath = p.join('.dart_tool', 'pub', 'workspace_ref.json');
+    final workspaceRefFile = File(workspaceRefPath);
+    if (!workspaceRefFile.existsSync()) return null;
+    final ref = jsonDecode(workspaceRefFile.readAsStringSync());
+    if (ref is! Map) return null;
+    final relativeRoot = ref['workspaceRoot'];
+    if (relativeRoot is! String) return null;
+    final packageGraphPath = p.normalize(
+      p.join(
+        '.dart_tool',
+        'pub',
+        relativeRoot,
+        '.dart_tool',
+        'package_graph.json',
+      ),
+    );
+    final packageGraphFile = File(packageGraphPath);
+    final packageGraph = jsonDecode(packageGraphFile.readAsStringSync());
+    if (packageGraph is! Map) return null;
+    final packages = packageGraph['packages'];
+    if (packages is! List) return null;
+    final testPackage = packages.firstWhereOrNull(
+      (p) => p is Map && p['name'] == 'test',
+    );
+    if (testPackage == null) return null;
+    return (testPackage as Map)['version'] as String;
+  } on FormatException {
+    return null;
+  } on IOException {
+    return null;
+  }
+}
+
+String? _readPubspecLock() {
+  dynamic lockfile;
+  try {
+    lockfile = loadYaml(File('pubspec.lock').readAsStringSync());
+  } on FormatException {
+    return null;
+  } on IOException {
+    return null;
+  }
+
+  if (lockfile is! Map) return null;
+  var packages = lockfile['packages'];
+  if (packages is! Map) return null;
+  var package = packages['test'];
+  if (package is! Map) return null;
+
+  var source = package['source'];
+  if (source is! String) return null;
+
+  switch (source) {
+    case 'hosted':
+      var version = package['version'];
+      return (version is String) ? version : null;
+
+    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)';
+
+    default:
+      return null;
+  }
+}