Add happy-path test cases for Model and ApiClient (#16)

Refactor `ApiClient` to go from `Map` to `Map` instead of bytes to
`String`. This makes it easier to write a stub client which is agnostic
to the ordering of values in the maps. Move the responsibilities for
UTF8 and JSON encoding to the `HttpApiClient`.

Eagerly call nested `.toJson()` methods for child fields in `.toJson()`
implementations. This allows deep equality checking for the stub client
without implementing `operator ==` for the data model classes.

Add a `createModelWithClient` method in `src/model.dart` which will not
be exported to the package public API. Use it in the test to create a
model with a stubbed client.

Add tests for each call in `GenerativeModel`. Tests validate
- Encoding from arguments to the JSON schema.
- Building the correct `Uri` for the task and model.
- Parsing the result to the Dart data model.

Add tests for unary and streaming calls in `HttpClient`. Tests validate
- Headers are set correctly.
- Encoding and decoding UTF8 and JSON.
- Using streaming with `alt=sse` query parameter and parsing of `data: `
  lines in the response.

Add Matcher helper methods for classes checked during tests that don't
have `operator ==`.

.github/workflows/google_generative_ai.yml

@@ -42,5 +42,5 @@ jobs:
       - run: dart format --output=none --set-exit-if-changed .
         if: ${{matrix.run-tests}}
 
-      # - run: dart test
-      #   if: ${{matrix.run-tests}}
+      - run: dart test
+        if: ${{matrix.run-tests}}

pkgs/google_generative_ai/lib/src/client.dart

@@ -14,45 +14,49 @@
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:typed_data';
 
 import 'package:http/http.dart' as http;
 
 abstract interface class ApiClient {
-  Future<String> makeRequest(Uri uri, Uint8List body);
-  Stream<String> streamRequest(Uri uri, Uint8List body);
+  Future<Map<String, Object?>> makeRequest(Uri uri, Map<String, Object?> body);
+  Stream<Map<String, Object?>> streamRequest(
+      Uri uri, Map<String, Object?> body);
 }
 
 const _packageVersion = '0.0.1';
-const _clientName = 'genai-dart/$_packageVersion';
+const clientName = 'genai-dart/$_packageVersion';
 
 final class HttpApiClient implements ApiClient {
   final String _apiKey;
   final http.Client? _httpClient;
   late final _headers = {
     'x-goog-api-key': _apiKey,
-    'x-goog-api-client': _clientName
+    'x-goog-api-client': clientName
   };
 
-  HttpApiClient(
-      {required String model, required String apiKey, http.Client? httpClient})
+  HttpApiClient({required String apiKey, http.Client? httpClient})
       : _apiKey = apiKey,
         _httpClient = httpClient ?? http.Client();
 
   @override
-  Future<String> makeRequest(Uri uri, Uint8List body) async {
-    final response = await http.post(uri,
-        headers: {..._headers, 'Content-Type': 'application/json'}, body: body);
-    return utf8.decode(response.bodyBytes);
+  Future<Map<String, Object?>> makeRequest(
+      Uri uri, Map<String, Object?> body) async {
+    final response = await http.post(
+      uri,
+      headers: {..._headers, 'Content-Type': 'application/json'},
+      body: utf8.encode(jsonEncode(body)),
+    );
+    return jsonDecode(utf8.decode(response.bodyBytes)) as Map<String, Object?>;
   }
 
   @override
-  Stream<String> streamRequest(Uri uri, Uint8List body) {
-    final controller = StreamController<String>();
+  Stream<Map<String, Object?>> streamRequest(
+      Uri uri, Map<String, Object?> body) {
+    final controller = StreamController<Map<String, Object?>>();
     () async {
       uri = uri.replace(queryParameters: {'alt': 'sse'});
       final request = http.Request('POST', uri)
-        ..bodyBytes = body
+        ..bodyBytes = utf8.encode(jsonEncode(body))
         ..headers.addAll(_headers)
         ..headers['Content-Type'] = 'application/json';
       final response = _httpClient == null
@@ -63,6 +67,8 @@ final class HttpApiClient implements ApiClient {
           .transform(const LineSplitter())
           .where((line) => line.startsWith('data: '))
           .map((line) => line.substring(6))
+          .map(jsonDecode)
+          .cast<Map<String, Object?>>()
           .pipe(controller);
     }();
     return controller.stream;

pkgs/google_generative_ai/lib/src/content.dart

@@ -27,7 +27,10 @@ final class Content {
   static Content multi(Iterable<Part> parts) => Content('user', [...parts]);
   static Content model(Iterable<Part> parts) => Content('model', [...parts]);
 
-  Map toJson() => {if (role case final role?) 'role': role, 'parts': parts};
+  Map toJson() => {
+        if (role case final role?) 'role': role,
+        'parts': parts.map((p) => p.toJson()).toList()
+      };
 }
 
 Content parseContent(Object jsonObject) {
@@ -52,18 +55,22 @@ Part _parsePart(Object? jsonObject) {
 }
 
 /// A datatype containing media that is part of a multi-part [Content] message.
-sealed class Part {}
+sealed class Part {
+  Object toJson();
+}
 
 final class TextPart implements Part {
   final String text;
   TextPart(this.text);
+  @override
   Object toJson() => {'text': text};
 }
 
 final class DataPart implements Part {
   final String mimeType;
   final Uint8List bytes;
   DataPart(this.mimeType, this.bytes);
+  @override
   Object toJson() => {
         'inlineData': {'data': base64Encode(bytes), 'mimeType': mimeType}
       };

pkgs/google_generative_ai/lib/src/model.dart

@@ -13,7 +13,6 @@
 // limitations under the License.
 
 import 'dart:async';
-import 'dart:convert';
 
 import 'package:http/http.dart' as http;
 
@@ -44,36 +43,35 @@ final class GenerativeModel {
   final List<SafetySetting> _safetySettings;
   final GenerationConfig? _generationConfig;
   final ApiClient _client;
-  GenerativeModel(
-      {required String model,
-      required String apiKey,
-      List<SafetySetting> safetySettings = const [],
-      GenerationConfig? generationConfig,
-      http.Client? httpClient})
-      :
+
+  factory GenerativeModel({
+    required String model,
+    required String apiKey,
+    List<SafetySetting> safetySettings = const [],
+    GenerationConfig? generationConfig,
+    http.Client? httpClient,
+  }) =>
+      GenerativeModel._withClient(
+          client: HttpApiClient(apiKey: apiKey, httpClient: httpClient),
+          model: model,
+          safetySettings: safetySettings,
+          generationConfig: generationConfig);
+
+  GenerativeModel._withClient({
+    required ApiClient client,
+    required String model,
+    required List<SafetySetting> safetySettings,
+    required GenerationConfig? generationConfig,
+  })  :
         // TODO: Allow `models/` prefix and strip it.
         // https://github.com/google/generative-ai-js/blob/2be48f8e5427f2f6191f24bcb8000b450715a0de/packages/main/src/models/generative-model.ts#L59
         _model = model,
         _safetySettings = safetySettings,
         _generationConfig = generationConfig,
-        _client =
-            HttpApiClient(model: model, apiKey: apiKey, httpClient: httpClient);
+        _client = client;
 
-  Future<Object> _makeRequest(
-      Task task, Map<String, Object?> parameters) async {
-    final uri = _baseUrl.resolveUri(
-        Uri(pathSegments: [_apiVersion, 'models', '$_model:${task._name}']));
-    final body = utf8.encode(jsonEncode(parameters));
-    final jsonString = await _client.makeRequest(uri, body);
-    return jsonDecode(jsonString) as Object;
-  }
-
-  Stream<Map<String, Object?>> _streamRequest(Task task, Object parameters) {
-    final uri = _baseUrl.resolveUri(
-        Uri(pathSegments: [_apiVersion, 'models', '$_model:${task._name}']));
-    final body = utf8.encode(jsonEncode(parameters));
-    return _client.streamRequest(uri, body).map(jsonDecode).cast();
-  }
+  Uri _taskUri(Task task) => _baseUrl.resolveUri(
+      Uri(pathSegments: [_apiVersion, 'models', '$_model:${task._name}']));
 
   /// Returns content responding to [prompt].
   ///
@@ -84,11 +82,14 @@ final class GenerativeModel {
   Future<GenerateContentResponse> generateContent(
       Iterable<Content> prompt) async {
     final parameters = {
-      'contents': prompt.toList(),
-      if (_safetySettings.isNotEmpty) 'safetySettings': _safetySettings,
-      if (_generationConfig case final config?) 'generationConfig': config,
+      'contents': prompt.map((p) => p.toJson()).toList(),
+      if (_safetySettings.isNotEmpty)
+        'safetySettings': _safetySettings.map((s) => s.toJson()).toList(),
+      if (_generationConfig case final config?)
+        'generationConfig': config.toJson(),
     };
-    final response = await _makeRequest(Task.generateContent, parameters);
+    final response =
+        await _client.makeRequest(_taskUri(Task.generateContent), parameters);
     return parseGenerateContentResponse(response);
   }
 
@@ -103,11 +104,14 @@ final class GenerativeModel {
   Stream<GenerateContentResponse> generateContentStream(
       Iterable<Content> prompt) {
     final parameters = <String, Object?>{
-      'contents': prompt.toList(),
-      if (_safetySettings.isNotEmpty) 'safetySettings': _safetySettings,
-      if (_generationConfig case final config?) 'generationConfig': config,
+      'contents': prompt.map((p) => p.toJson()).toList(),
+      if (_safetySettings.isNotEmpty)
+        'safetySettings': _safetySettings.map((s) => s.toJson()).toList(),
+      if (_generationConfig case final config?)
+        'generationConfig': config.toJson(),
     };
-    final response = _streamRequest(Task.streamGenerateContent, parameters);
+    final response =
+        _client.streamRequest(_taskUri(Task.streamGenerateContent), parameters);
     return response.map(parseGenerateContentResponse);
   }
 
@@ -124,8 +128,11 @@ final class GenerativeModel {
   ///       print(response.text);
   ///     }
   Future<CountTokensResponse> countTokens(Iterable<Content> content) async {
-    final parameters = <String, Object?>{'contents': content.toList()};
-    final response = await _makeRequest(Task.countTokens, parameters);
+    final parameters = <String, Object?>{
+      'contents': content.map((c) => c.toJson()).toList()
+    };
+    final response =
+        await _client.makeRequest(_taskUri(Task.countTokens), parameters);
     return parseCountTokensResponse(response);
   }
 
@@ -138,11 +145,26 @@ final class GenerativeModel {
   Future<EmbedContentResponse> embedContent(Content content,
       {TaskType? taskType, String? title}) async {
     final parameters = <String, Object?>{
-      'content': content,
-      if (taskType != null) 'taskType': taskType,
+      'content': content.toJson(),
+      if (taskType != null) 'taskType': taskType.toJson(),
       if (title != null) 'title': title
     };
-    final response = await _makeRequest(Task.embedContent, parameters);
+    final response =
+        await _client.makeRequest(_taskUri(Task.embedContent), parameters);
     return parseEmbedContentReponse(response);
   }
 }
+
+/// Create a model with an overridden [ApiClient] for testing.
+///
+/// Package private test only method.
+GenerativeModel createModelwithClient(
+        {required String model,
+        required ApiClient client,
+        List<SafetySetting> safetySettings = const [],
+        GenerationConfig? generationConfig}) =>
+    GenerativeModel._withClient(
+        client: client,
+        model: model,
+        safetySettings: safetySettings,
+        generationConfig: generationConfig);

pkgs/google_generative_ai/pubspec.yaml

@@ -10,10 +10,11 @@ environment:
   sdk: ^3.2.0
 
 dependencies:
-  crypt: ^4.3.0
   http: ^1.1.0
   pool: ^1.5.0
 
 dev_dependencies:
+  collection: ^1.18.0
   lints: ^3.0.0
+  matcher: ^0.12.16
   test: ^1.24.0