Add integration tests

test/unknown_properties_in_description_test.dart

@@ -0,0 +1,104 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// 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 'package:pub/src/exit_codes.dart';
+import 'package:test/test.dart';
+
+import 'descriptor.dart' as d;
+import 'test_pub.dart';
+
+void main() {
+  test('Ignores additional properties in descriptions before 3.7', () async {
+    final server = await servePackages();
+    server.serve(
+      'foo',
+      '1.0.0',
+      sdk: '^3.6.0',
+      deps: {
+        'bar': {
+          'hosted': {'url': server.url, 'unknown': 11},
+        },
+      },
+    );
+    server.serve('bar', '1.0.0');
+    await d.appDir(
+      pubspec: {
+        'environment': {'sdk': '^3.6.0'},
+      },
+      dependencies: {
+        'foo': {
+          'hosted': {'url': server.url, 'unknown': 11},
+          'version': '^1.0.0',
+        },
+      },
+    ).create();
+    await pubGet(environment: {'_PUB_TEST_SDK_VERSION': '3.7.0'});
+  });
+
+  test('Detects unknown attributes in descriptions in root project after 3.7',
+      () async {
+    final server = await servePackages();
+    server.serve(
+      'foo',
+      '1.0.0',
+      sdk: '^3.6.0',
+      deps: {
+        'bar': {
+          'hosted': {'url': server.url, 'unknown': 11},
+        },
+      },
+    );
+    server.serve('bar', '1.0.0');
+    await d.appDir(
+      pubspec: {
+        'environment': {'sdk': '^3.7.0'},
+      },
+      dependencies: {
+        'foo': {
+          'hosted': {'url': server.url, 'unknown': 11},
+          'version': '^1.0.0',
+        },
+      },
+    ).create();
+    await pubGet(
+      environment: {'_PUB_TEST_SDK_VERSION': '3.7.0'},
+      error: contains('Invalid description in the "myapp" pubspec '
+          'on the "foo" dependency: Unknown key "unknown" in description.'),
+      exitCode: DATA,
+    );
+  });
+
+  test('Detects unknown attributes in descriptions in dependency after 3.7',
+      () async {
+    final server = await servePackages();
+    server.serve(
+      'foo',
+      '1.0.0',
+      sdk: '^3.7.0',
+      deps: {
+        'bar': {
+          'hosted': {'url': server.url, 'unknown': 11},
+        },
+      },
+    );
+    server.serve('bar', '1.0.0');
+    await d.appDir(
+      pubspec: {
+        'environment': {'sdk': '^3.6.0'},
+      },
+      dependencies: {
+        'foo': {
+          'hosted': {'url': server.url, 'unknown': 11},
+          'version': '^1.0.0',
+        },
+      },
+    ).create();
+    await pubGet(
+      environment: {'_PUB_TEST_SDK_VERSION': '3.7.0'},
+      error: contains('Invalid description in the "foo" pubspec '
+          'on the "bar" dependency: Unknown key "unknown" in description.'),
+      exitCode: DATA,
+    );
+  });
+}