Writing unit tests and Updating Dart SDK to support null safety

example/pubspec.yaml

@@ -14,15 +14,14 @@ description: A new Flutter project.
 version: 1.0.0+1
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: ">=2.17.1 <3.0.0"
 
 dependencies:
   flutter:
     sdk: flutter
 
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.
-  cupertino_icons: ^0.1.2
   persian_number_utility:
 
 dev_dependencies:

pubspec.yaml

@@ -5,3 +5,5 @@ homepage: https://github.com/mehdi-nemati/persian_number_utility
 
 environment:
   sdk: '>=2.12.0 <3.0.0'
+dev_dependencies:
+  test: ^1.25.2

test/persian_number_utility_test.dart

@@ -1,6 +1,57 @@
-// import 'package:flutter_test/flutter_test.dart';
+import 'package:test/test.dart';
+import 'package:persian_number_utility/persian_number_utility.dart';
 
-// void main() {
-//   test('adds one to input values', () {
-//   });
-// }
+void main() {
+  group('Number to word methods', () {
+    group('converting English numbers to words', () {
+      test('1000 to english word', () {
+        expect(NumberUtility.toWord('1000', NumStrLanguage.English),
+            'one thousand');
+      });
+      test('100 to english word', () {
+        expect(
+            NumberUtility.toWord('100', NumStrLanguage.English), 'one hundred');
+      });
+    });
+
+    group('converting Farsi numbers to words', () {
+      test('1000 to persian word', () {
+        expect(NumberUtility.toWord('1000', NumStrLanguage.Farsi), 'هزار');
+      });
+      test('100 to persian word', () {
+        expect(NumberUtility.toWord('100', NumStrLanguage.Farsi), 'صد');
+      });
+      test('10522 to persian word', () {
+        expect(NumberUtility.toWord('10522', NumStrLanguage.Farsi),
+            'ده هزار و پانصد و بیست و دو');
+      });
+    });
+  });
+
+  group('Persian word to number methods', () {
+    test('converting 21000', () {
+      expect(NumberUtility.toNumber('بیست و یک هزار'), 21000);
+    });
+    test('converting 21000', () {
+      expect(NumberUtility.toNumber('صد و بیست و دو'), 122);
+    });
+  });
+
+  group('seRagham method test', () {
+    test('seRagham', () {
+      expect(NumberUtility.seRagham('122500000'), '122,500,000');
+    });
+    test('seRagham with custom separator', () {
+      expect(NumberUtility.seRagham('99999999',separator: '|'), '99|999|999');
+    });
+  });
+
+    group('changeDigit method test', () {
+    test('English to Persian digits', () {
+      expect(NumberUtility.changeDigit('1234567890',NumStrLanguage.Farsi), '۱۲۳۴۵۶۷۸۹۰');
+    });
+    test('Persian to English digits', () {
+      expect(NumberUtility.changeDigit('۱۲۳۴۵۶۷۸۹۰',NumStrLanguage.English), '1234567890');
+    });
+  });
+}