test: add tests for requestThingDescription method

test/core/discovery_test.dart

@@ -0,0 +1,165 @@
+// Copyright 2023 Contributors to the Eclipse Foundation. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+import 'dart:convert';
+
+import 'package:dart_wot/dart_wot.dart';
+import 'package:dart_wot/src/core/content.dart';
+import 'package:dart_wot/src/core/thing_discovery.dart';
+import 'package:test/test.dart';
+
+const testUriScheme = 'test';
+final validTestDiscoveryUri =
+    Uri.parse('$testUriScheme://[::1]/.well-known/wot');
+final invalidTestDiscoveryUri =
+    Uri.parse('$testUriScheme://[::2]/.well-known/wot');
+
+const validTestTitle = 'Test TD';
+const validTestThingDescription = '''
+  {
+      "@context": "https://www.w3.org/2022/wot/td/v1.1",
+      "title": "$validTestTitle",
+      "security": "nosec_sc",
+      "securityDefinitions": {
+        "nosec_sc": {"scheme": "nosec"}
+      }
+  }
+''';
+
+const invalidTestThingDescription = '"Hi there!"';
+
+void main() {
+  group('Discovery Tests', () {
+    test('Should be able to use the requestThingDescription method', () async {
+      final servient = Servient(
+        clientFactories: [
+          _MockedProtocolClientFactory(),
+        ],
+      );
+
+      final wot = await servient.start();
+      final thingDescription =
+          await wot.requestThingDescription(validTestDiscoveryUri);
+
+      expect(thingDescription.title, validTestTitle);
+    });
+
+    test(
+      'Should throw an exception if an invalid TD results from the '
+      'requestThingDescription method',
+      () async {
+        final servient = Servient(
+          clientFactories: [
+            _MockedProtocolClientFactory(),
+          ],
+        );
+
+        final wot = await servient.start();
+        await expectLater(
+          wot.requestThingDescription(invalidTestDiscoveryUri),
+          // TODO: Refine error handling
+          throwsA(isA<DiscoveryException>()),
+        );
+      },
+    );
+  });
+}
+
+class _MockedProtocolClient implements ProtocolClient {
+  @override
+  Stream<DiscoveryContent> discoverWithCoreLinkFormat(Uri uri) {
+    // TODO: implement discoverWithCoreLinkFormat
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<Content> invokeResource(Form form, Content content) {
+    // TODO: implement invokeResource
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<Content> readResource(Form form) {
+    // TODO: implement readResource
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<Content> requestThingDescription(Uri url) async {
+    if (url == validTestDiscoveryUri) {
+      return validTestThingDescription.toDiscoveryContent(url);
+    }
+
+    if (url == invalidTestDiscoveryUri) {
+      return invalidTestThingDescription.toDiscoveryContent(url);
+    }
+
+    throw StateError('Encountered invalid URL.');
+  }
+
+  @override
+  Future<void> start() async {
+    // Do nothing
+  }
+
+  @override
+  Future<void> stop() async {
+    // Do nothing
+  }
+
+  @override
+  Future<Subscription> subscribeResource(
+    Form form, {
+    required void Function(Content content) next,
+    void Function(Exception error)? error,
+    required void Function() complete,
+  }) {
+    // TODO: implement subscribeResource
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<void> writeResource(Form form, Content content) {
+    // TODO: implement writeResource
+    throw UnimplementedError();
+  }
+
+  @override
+  Stream<DiscoveryContent> discoverDirectly(
+    Uri uri, {
+    bool disableMulticast = false,
+  }) {
+    // TODO: implement discoverDirectly
+    throw UnimplementedError();
+  }
+}
+
+class _MockedProtocolClientFactory implements ProtocolClientFactory {
+  @override
+  ProtocolClient createClient() {
+    return _MockedProtocolClient();
+  }
+
+  @override
+  bool destroy() {
+    return true;
+  }
+
+  @override
+  bool init() {
+    return true;
+  }
+
+  @override
+  Set<String> get schemes => {testUriScheme};
+}
+
+extension _DiscoveryContentCreationExtension on String {
+  DiscoveryContent toDiscoveryContent(Uri url) {
+    final body = Stream.fromIterable([utf8.encode(this)]);
+    return DiscoveryContent('application/td+json', body, url);
+  }
+}