add EmailType test

@@ -13,13 +13,14 @@ enum EmailType {
 
   factory EmailType.fromRawValue(int value) {
     switch (value) {
+      case 0:
+        return EmailType.unknown;
       case 1:
         return EmailType.work;
       case 2:
         return EmailType.home;
-      case 0:
       default:
-        return EmailType.unknown;
+        throw ArgumentError.value(value, 'value', 'Invalid raw value.');
     }
   }
 

+import 'package:flutter_test/flutter_test.dart';
+import 'package:mobile_scanner/src/enums/email_type.dart';
+
+void main() {
+  group('$EmailType tests', () {
+    test('can be created from raw value', () {
+      const values = <int, EmailType>{
+        0: EmailType.unknown,
+        1: EmailType.work,
+        2: EmailType.home,
+      };
+
+      for (final MapEntry<int, EmailType> entry in values.entries) {
+        final EmailType result = EmailType.fromRawValue(entry.key);
+
+        expect(result, entry.value);
+      }
+    });
+
+    test('invalid raw value throws argument error', () {
+      const int negative = -1;
+      const int outOfRange = 3;
+
+      expect(() => EmailType.fromRawValue(negative), throwsArgumentError);
+      expect(() => EmailType.fromRawValue(outOfRange), throwsArgumentError);
+    });
+
+    test('can be converted to raw value', () {
+      const values = <EmailType, int>{
+        EmailType.unknown: 0,
+        EmailType.work: 1,
+        EmailType.home: 2,
+      };
+
+      for (final MapEntry<EmailType, int> entry in values.entries) {
+        final int result = entry.key.rawValue;
+
+        expect(result, entry.value);
+      }
+    });
+  });
+}