api: Add createSavedSnippet route

Author: PIG208

lib/api/route/saved_snippets.dart

@@ -0,0 +1,30 @@
+import 'package:json_annotation/json_annotation.dart';
+
+import '../core.dart';
+
+part 'saved_snippets.g.dart';
+
+/// https://zulip.com/api/create-saved-snippet
+Future<CreateSavedSnippetResult> createSavedSnippet(ApiConnection connection, {
+  required String title,
+  required String content,
+}) {
+  return connection.post('createSavedSnippet', CreateSavedSnippetResult.fromJson, 'saved_snippets', {
+    'title': RawParameter(title),
+    'content': RawParameter(content),
+  });
+}
+
+@JsonSerializable(fieldRename: FieldRename.snake)
+class CreateSavedSnippetResult {
+  final int savedSnippetId;
+
+  CreateSavedSnippetResult({
+    required this.savedSnippetId,
+  });
+
+  factory CreateSavedSnippetResult.fromJson(Map<String, dynamic> json) =>
+    _$CreateSavedSnippetResultFromJson(json);
+
+  Map<String, dynamic> toJson() => _$CreateSavedSnippetResultToJson(this);
+}

lib/api/route/saved_snippets.g.dart

@@ -0,0 +1,25 @@
+import 'package:checks/checks.dart';
+import 'package:http/http.dart' as http;
+import 'package:flutter_test/flutter_test.dart';
+import 'package:zulip/api/route/saved_snippets.dart';
+
+import '../../stdlib_checks.dart';
+import '../fake_api.dart';
+import '../route/route_checks.dart';
+
+void main() {
+  test('smoke', () async {
+    return FakeApiConnection.with_((connection) async {
+      connection.prepare(
+        json: CreateSavedSnippetResult(savedSnippetId: 123).toJson());
+      final result = await createSavedSnippet(connection,
+        title: 'test saved snippet', content: 'content');
+      check(result).savedSnippetId.equals(123);
+      check(connection.takeRequests()).single.isA<http.Request>()
+        .bodyFields.deepEquals({
+        'title': 'test saved snippet',
+        'content': 'content',
+      });
+    });
+  });
+}

test/api/model/saved_snippets_test.dart

@@ -1,8 +1,12 @@
 import 'package:checks/checks.dart';
 import 'package:zulip/api/route/messages.dart';
+import 'package:zulip/api/route/saved_snippets.dart';
 
 extension SendMessageResultChecks on Subject<SendMessageResult> {
   Subject<int> get id => has((e) => e.id, 'id');
 }
+extension CreateSavedSnippetResultChecks on Subject<CreateSavedSnippetResult> {
+  Subject<int> get savedSnippetId => has((e) => e.savedSnippetId, 'savedSnippetId');
+}
 
 // TODO add similar extensions for other classes in api/route/*.dart