App localization test was created for increasing coverage and reliability

test/utils/app_localization_test.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:talawa/utils/app_localization.dart';
+
+void main() {
+  group("Test for App Localization Class", () {
+    WidgetsFlutterBinding.ensureInitialized();
+
+    test("Load JSON File for localizations", () async {
+      final appLocalizations = AppLocalizations(const Locale('en'));
+      final result = await appLocalizations.load();
+      expect(result, true);
+    });
+
+    test("Test mode working properly", () async {
+      final appLocalizations =
+          AppLocalizations(const Locale('hi'), isTest: true);
+      final result = await appLocalizations.load();
+      expect(result, true);
+
+      expect(appLocalizations.strictTranslate("Recover"), "Recover");
+    });
+
+    test("Translate and strict translate", () async {
+      final appLocalizations = AppLocalizations(const Locale('en'));
+      final result = await appLocalizations.load();
+      expect(result, true);
+
+      // Translate known value
+      const key = "Please verify URL first";
+      const trueData = "Please verify URL first";
+      final checkData = appLocalizations.translate(key);
+      expect(checkData, trueData);
+
+      // Translate unknown value
+      const key2 = "Lorem ipsum";
+      expect(appLocalizations.translate(key2), null);
+
+      // Translate null value
+      expect(appLocalizations.translate(null), "...");
+
+      //Strict translate known value
+      expect(appLocalizations.strictTranslate("Liked by"), "Liked by");
+
+      // Strict translate unknown value
+      expect(appLocalizations.strictTranslate(key2), key2);
+    });
+  });
+
+  group("Test for App Localization Delegate", () {
+    WidgetsFlutterBinding.ensureInitialized();
+    const appLocalizationsDelgate = AppLocalizationsDelegate();
+
+    test("Language is supported or not", () {
+      // A supported language
+      expect(appLocalizationsDelgate.isSupported(const Locale('hi')), true);
+
+      // An unsupported language
+      expect(appLocalizationsDelgate.isSupported(const Locale('or')), false);
+    });
+
+    test("Localization loaded and changed properly", () async {
+      var testAppLocalization =
+          await appLocalizationsDelgate.load(const Locale('hi'));
+
+      // In test mode
+      testAppLocalization.isTest = true;
+      expect(testAppLocalization.strictTranslate("Recover"), "Recover");
+
+      // In prod mode
+      testAppLocalization.isTest = false;
+      expect(testAppLocalization.strictTranslate("Recover"), "रिकवर कर लेंगे");
+
+      testAppLocalization =
+          await appLocalizationsDelgate.load(const Locale('fr'));
+
+      // In test mode
+      testAppLocalization.isTest = true;
+      expect(testAppLocalization.strictTranslate("Recover"), "Recover");
+
+      // In prod mode
+      testAppLocalization.isTest = false;
+      expect(testAppLocalization.strictTranslate("Recover"), "votre mot");
+    });
+
+    test("App Localization Delegate should not reload", () async {
+      expect(
+        appLocalizationsDelgate.shouldReload(appLocalizationsDelgate),
+        false,
+      );
+    });
+  });
+}