Better error for duplicate workspace entries (#4385)

Author: sigurdm

lib/src/package.dart

@@ -407,12 +407,20 @@ void validateWorkspace(Package root) {
     for (final child in current.workspaceChildren) {
       final previous = includedFrom[p.canonicalize(child.dir)];
       if (previous != null) {
+        if (previous == current.dir) {
+          fail(
+            '''
+Packages can only be included in the workspace once.
+
+`${p.join(child.dir, 'pubspec.yaml')}` is included twice into the workspace of `${p.join(current.dir, 'pubspec.yaml')}`''',
+          );
+        }
         fail('''
 Packages can only be included in the workspace once.
 
 `${p.join(child.dir, 'pubspec.yaml')}` is included in the workspace, both from:
 * `${p.join(current.dir, 'pubspec.yaml')}` and
-* ${p.join(previous, 'pubspec.yaml')}.''');
+* `${p.join(previous, 'pubspec.yaml')}`.''');
       }
       includedFrom[p.canonicalize(child.dir)] = current.dir;
     }

pubspec.lock

@@ -5,23 +5,23 @@ packages:
     dependency: transitive
     description:
       name: _fe_analyzer_shared
-      sha256: f6dbf021f4b214d85c79822912c5fcd142a2c4869f01222ad371bc51f9f1c356
+      sha256: "45cfa8471b89fb6643fe9bf51bd7931a76b8f5ec2d65de4fb176dba8d4f22c77"
       url: "https://pub.dev"
     source: hosted
-    version: "74.0.0"
+    version: "73.0.0"
   _macros:
     dependency: transitive
     description: dart
     source: sdk
-    version: "0.3.3"
+    version: "0.3.2"
   analyzer:
     dependency: "direct main"
     description:
       name: analyzer
-      sha256: f7e8caf82f2d3190881d81012606effdf8a38e6c1ab9e30947149733065f817c
+      sha256: "4959fec185fe70cce007c57e9ab6983101dbe593d2bf8bbfb4453aaec0cf470a"
       url: "https://pub.dev"
     source: hosted
-    version: "6.9.0"
+    version: "6.8.0"
   args:
     dependency: "direct main"
     description:
@@ -194,10 +194,10 @@ packages:
     dependency: transitive
     description:
       name: macros
-      sha256: "1d9e801cd66f7ea3663c45fc708450db1fa57f988142c64289142c9b7ee80656"
+      sha256: "0acaed5d6b7eab89f63350bccd82119e6c602df0f391260d0e32b5e23db79536"
       url: "https://pub.dev"
     source: hosted
-    version: "0.1.3-main.0"
+    version: "0.1.2-main.4"
   matcher:
     dependency: transitive
     description:

test/workspace_test.dart

@@ -791,7 +791,44 @@ Packages can only be included in the workspace once.
 
 `.${s}pkgs${s}a${s}pubspec.yaml` is included in the workspace, both from:
 * `.${s}pkgs${s}pubspec.yaml` and
-* .${s}pubspec.yaml.''',
+* `.${s}pubspec.yaml`.''',
+      environment: {'_PUB_TEST_SDK_VERSION': '3.5.0'},
+    );
+  });
+
+  test('Reports error if workspace has repeat item', () async {
+    await dir(appPath, [
+      libPubspec(
+        'myapp',
+        '1.2.3',
+        sdk: '^3.5.0',
+        extras: {
+          'workspace': ['pkgs/a', 'pkgs/a/'],
+        },
+      ),
+      dir('pkgs', [
+        libPubspec(
+          'a',
+          '1.1.1',
+          resolutionWorkspace: true,
+          extras: {
+            'workspace': ['a'],
+          },
+        ),
+        dir(
+          'a',
+          [
+            libPubspec('a', '1.1.1', resolutionWorkspace: true),
+          ],
+        ),
+      ]),
+    ]).create();
+    final s = p.separator;
+    await pubGet(
+      error: '''
+Packages can only be included in the workspace once.
+
+`.${s}pkgs/a/pubspec.yaml` is included twice into the workspace of `.${s}pubspec.yaml`''',
       environment: {'_PUB_TEST_SDK_VERSION': '3.5.0'},
     );
   });