core: Add translations for exceptions related to api requests

Also hook up some other test suites that require localization
contexts for tests to pass given this change.

Author: sirpengi

assets/l10n/app_en.arb

@@ -15,6 +15,10 @@
   "@aboutPageTapToView": {
     "description": "Item subtitle in About Zulip page to navigate to Licenses page"
   },
+  "apiConnectionNetworkRequestFailed": "Network request failed",
+  "@apiConnectionNetworkRequestFailed": {
+    "description": "Message for error dialog when a network request fails."
+  },
   "chooseAccountPageTitle": "Choose account",
   "@chooseAccountPageTitle": {
     "description": "Title for ChooseAccountPage"
@@ -49,6 +53,26 @@
       }
     }
   },
+  "serverExceptionMalformedResponse": "Server gave malformed response; HTTP status {httpStatus}",
+  "@serverExceptionMalformedResponse": {
+    "description": "Message for error dialog when an API call fails because we could not parse it.",
+    "placeholders": {
+      "httpStatus": {
+        "type": "int",
+        "example": "500"
+      }
+    }
+  },
+  "serverExceptionRequestFailed": "Network request failed: HTTP status {httpStatus}",
+  "@serverExceptionRequestFailed": {
+    "description": "Message for error dialog when an API call fails.",
+    "placeholders": {
+      "httpStatus": {
+        "type": "int",
+        "example": "500"
+      }
+    }
+  },
   "userRoleOwner": "Owner",
   "@userRoleOwner": {
     "description": "Label for UserRole.owner"

lib/api/core.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
 import 'package:http/http.dart' as http;
 
 import '../log.dart';
@@ -84,15 +85,25 @@ class ApiConnection {
     try {
       response = await _client.send(request);
     } catch (e) {
-      final String message;
+      final String? message;
+      final String Function(ZulipLocalizations)? translatableMessage;
       if (e is http.ClientException) {
         message = e.message;
+        translatableMessage = null;
       } else if (e is TlsException) {
         message = e.message;
+        translatableMessage = null;
       } else {
-        message = 'Network request failed';
+        message = null;
+        translatableMessage = (ZulipLocalizations zulipLocalizations) {
+          return zulipLocalizations.apiConnectionNetworkRequestFailed;
+        };
       }
-      throw NetworkException(routeName: routeName, cause: e, message: message);
+      throw NetworkException(
+        routeName: routeName,
+        cause: e,
+        message: message,
+        translatableMessage: translatableMessage);
     }
 
     final int httpStatus = response.statusCode;
@@ -173,6 +184,7 @@ ApiRequestException _makeApiException(String routeName, int httpStatus, Map<Stri
         // TODO(server): `code` should always be present.  Get the "Invalid API key" case fixed.
         code: json.remove('code') ?? 'BAD_REQUEST',
         message: json.remove('msg'),
+        translatableMessage: null,
         data: json,
       );
     }

lib/api/exception.dart

@@ -1,4 +1,6 @@
 
+import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
+
 /// Some kind of error from a Zulip API network request.
 sealed class ApiRequestException implements Exception {
   /// The name of the Zulip API route for the request.
@@ -11,13 +13,26 @@ sealed class ApiRequestException implements Exception {
   /// and its route name would be "getMessages".
   final String routeName;
 
-  /// A user-facing description of the error.
+  /// Server supplied user-facing description of the error.
+  ///
+  /// For [ZulipApiException] this may be supplied by the server as the `message`
+  /// property in the JSON response.
+  // TODO(i18n): no method yet to translate a server provided string.
+  final String? message;
+
+  /// App supplied user-facing description of the error.
   ///
-  /// For [ZulipApiException] this is supplied by the server as the `message`
-  /// property in the JSON response, and is translated into the user's language.
-  final String message;
+  /// This description will be translated according to the
+  /// current set locale.
+  final String Function(ZulipLocalizations)? translatableMessage;
+
+  ApiRequestException({required this.routeName, required this.message, required this.translatableMessage});
 
-  ApiRequestException({required this.routeName, required this.message});
+  String toTranslatedString(ZulipLocalizations zulipLocalizations) {
+    return (translatableMessage != null)
+      ? translatableMessage!(zulipLocalizations)
+      : super.toString();
+  }
 }
 
 /// An error returned through the Zulip server API.
@@ -46,6 +61,7 @@ class ZulipApiException extends ApiRequestException {
     required this.httpStatus,
     required this.data,
     required super.message,
+    required super.translatableMessage,
   }) : assert(400 <= httpStatus && httpStatus <= 499);
 }
 
@@ -58,7 +74,7 @@ class NetworkException extends ApiRequestException {
   /// but empirically it can be [TlsException] and possibly others.
   final Object cause;
 
-  NetworkException({required super.routeName, required super.message, required this.cause});
+  NetworkException({required super.routeName, required super.message, required super.translatableMessage, required this.cause});
 }
 
 /// Some kind of server-side error in handling the request.
@@ -79,6 +95,7 @@ abstract class ServerException extends ApiRequestException {
     required this.httpStatus,
     required this.data,
     required super.message,
+    required super.translatableMessage,
   });
 }
 
@@ -89,7 +106,11 @@ class Server5xxException extends ServerException {
     required super.httpStatus,
     required super.data,
   }) : assert(500 <= httpStatus && httpStatus <= 599),
-       super(message: 'Network request failed: HTTP status $httpStatus'); // TODO(i18n)
+       super(
+         message: null,
+         translatableMessage: (ZulipLocalizations zulipLocalizations) {
+           return zulipLocalizations.serverExceptionRequestFailed(httpStatus);
+         });
 }
 
 /// An error where the server's response doesn't match the Zulip API.
@@ -110,5 +131,9 @@ class MalformedServerResponseException extends ServerException {
     required super.routeName,
     required super.httpStatus,
     required super.data,
-  }) : super(message: 'Server gave malformed response; HTTP status $httpStatus'); // TODO(i18n)
+  }) : super(
+         message: null,
+         translatableMessage: (ZulipLocalizations zulipLocalizations) {
+           return zulipLocalizations.serverExceptionMalformedResponse(httpStatus);
+         });
 }

test/api/core_test.dart

@@ -3,6 +3,7 @@ import 'dart:io';
 
 import 'package:checks/checks.dart';
 import 'package:checks/context.dart';
+import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
 import 'package:http/http.dart' as http;
 import 'package:test/scaffolding.dart';
 import 'package:zulip/api/core.dart';
@@ -155,7 +156,11 @@ void main() {
 
     checkRequest(http.ClientException('Oops'), it()..message.equals('Oops'));
     checkRequest(const TlsException('Oops'), it()..message.equals('Oops'));
-    checkRequest((foo: 'bar'), it()..message.equals('Network request failed'));
+    final zulipLocalizations = lookupZulipLocalizations(ZulipLocalizations.supportedLocales.first);
+    final expectedMessage = zulipLocalizations.apiConnectionNetworkRequestFailed;
+    checkRequest((foo: 'bar'), it()
+      ..toTranslatedString(zulipLocalizations)
+      .equals(expectedMessage));
   });
 
   test('API 4xx errors, well formed', () async {

test/api/exception_checks.dart

@@ -1,9 +1,12 @@
 import 'package:checks/checks.dart';
+import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
 import 'package:zulip/api/exception.dart';
 
 extension ApiRequestExceptionChecks on Subject<ApiRequestException> {
   Subject<String> get routeName => has((e) => e.routeName, 'routeName');
-  Subject<String> get message => has((e) => e.message, 'message');
+  Subject<String?> get message => has((e) => e.message, 'message');
+  Subject<String> toTranslatedString(ZulipLocalizations zulipLocalizations) =>
+    has((e) => e.toTranslatedString(zulipLocalizations), 'getTranslatedMessage');
 }
 
 extension ZulipApiExceptionChecks on Subject<ZulipApiException> {

test/widgets/autocomplete_test.dart

@@ -1,5 +1,6 @@
 import 'package:checks/checks.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/route/messages.dart';
@@ -40,6 +41,8 @@ Future<Finder> setupToComposeInput(WidgetTester tester, {
 
   await tester.pumpWidget(
     MaterialApp(
+      localizationsDelegates: ZulipLocalizations.localizationsDelegates,
+      supportedLocales: ZulipLocalizations.supportedLocales,
       home: GlobalStoreWidget(
         child: PerAccountStoreWidget(
           accountId: eg.selfAccount.id,

test/widgets/clipboard_test.dart

@@ -32,7 +32,6 @@ void main() {
             body: Builder(builder: (context) => Center(
               child: ElevatedButton(
                 onPressed: () async {
-                  // TODO(i18n)
                   copyWithPopup(context: context, successContent: const Text('Text copied'),
                     data: ClipboardData(text: text));
                 },

test/widgets/content_test.dart

@@ -3,6 +3,7 @@ import 'dart:io';
 import 'package:checks/checks.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:url_launcher/url_launcher.dart';
 import 'package:zulip/api/core.dart';
@@ -68,6 +69,8 @@ void main() {
       addTearDown(testBinding.reset);
 
       await tester.pumpWidget(GlobalStoreWidget(child: MaterialApp(
+        localizationsDelegates: ZulipLocalizations.localizationsDelegates,
+        supportedLocales: ZulipLocalizations.supportedLocales,
         home: PerAccountStoreWidget(accountId: eg.selfAccount.id,
           child: BlockContentList(
             nodes: parseContent(html).nodes)))));