feat(mcp): allow the test tool to target specific paths

The `test` tool exposed no way to run a subset of a suite, so every call
ran everything. The CLI already supports positional test targets — the
test command forwards `argResults.rest` to the runner — but the MCP tool
had no argument that reached them, and `directory` is deliberately
applied as the working directory rather than as a target.

Adds an optional `paths` array that is appended after every option, so
the args land in `rest`. Behaviour matches the CLI, including the
existing rule that targeting specific files disables test optimization.

Author: HadiHassan22

lib/src/mcp/mcp_server.dart

@@ -174,6 +174,14 @@ If is omitted, then core will be selected.
                   'Target directory path (defaults to current directory). '
                   'Can be absolute or relative path to project root.',
             ),
+            'paths': ListSchema(
+              description:
+                  'Test files or directories to run, relative to the project '
+                  "root (e.g. ['test/src/foo_test.dart', 'test/widgets']). "
+                  'When omitted, the whole suite runs. Note that targeting '
+                  'specific paths disables the test optimization step.',
+              items: StringSchema(),
+            ),
             'dart': BooleanSchema(
               description:
                   '''Whether to run Dart tests. If not specified, Flutter tests will be run if a Flutter project is detected.''',
@@ -452,6 +460,13 @@ Only one value can be selected.
       ]);
     }
 
+    // Positional test targets go last, after every option, so that they are
+    // parsed as `rest` rather than as a value for the preceding option.
+    final paths = args['paths'] as List<Object?>?;
+    if (paths != null) {
+      cliArgs.addAll(paths.cast<String>());
+    }
+
     return cliArgs;
   }
 

test/src/mcp/mcp_server_test.dart

@@ -502,6 +502,69 @@ void main() {
                 as List<String>;
         expect(capturedArgs, equals(['test', '--timeout', '120']));
       });
+
+      test('passes paths as positional test targets', () async {
+        await sendRequest(
+          CallToolRequest.methodName,
+          _params(
+            CallToolRequest(
+              name: 'test',
+              arguments: {
+                'paths': ['test/src/foo_test.dart', 'test/widgets'],
+              },
+            ),
+          ),
+        );
+
+        final capturedArgs =
+            verify(() => mockCommandRunner.run(captureAny())).captured.first
+                as List<String>;
+        expect(
+          capturedArgs,
+          equals(['test', 'test/src/foo_test.dart', 'test/widgets']),
+        );
+      });
+
+      test('passes paths after options so they are parsed as rest', () async {
+        await sendRequest(
+          CallToolRequest.methodName,
+          _params(
+            CallToolRequest(
+              name: 'test',
+              arguments: {
+                'dart': true,
+                'concurrency': '8',
+                'paths': ['test/src/foo_test.dart'],
+              },
+            ),
+          ),
+        );
+
+        final capturedArgs =
+            verify(() => mockCommandRunner.run(captureAny())).captured.first
+                as List<String>;
+        expect(
+          capturedArgs,
+          equals(['dart', 'test', '-j', '8', 'test/src/foo_test.dart']),
+        );
+      });
+
+      test('adds no positional targets when paths is empty', () async {
+        await sendRequest(
+          CallToolRequest.methodName,
+          _params(
+            CallToolRequest(
+              name: 'test',
+              arguments: {'paths': <String>[]},
+            ),
+          ),
+        );
+
+        final capturedArgs =
+            verify(() => mockCommandRunner.run(captureAny())).captured.first
+                as List<String>;
+        expect(capturedArgs, equals(['test']));
+      });
     });
 
     group('Tool: packages_get', () {