diff --git a/README.md b/README.md
index 9b652eae..1acdefca 100644
--- a/README.md
+++ b/README.md
@@ -71,3 +71,12 @@ The example for VS Code is below:
             "type": "dart"
         }
     ]
+
+To check the code quality with Flutter Analyzer (recommended when you want to add something) please run in console:
+
+    flutter analyze
+
+It should give no errors message:
+
+    Analyzing openflutterecommerceapp...
+    No issues found! (ran in 3.5s)
\ No newline at end of file
diff --git a/analysis_options.yaml b/analysis_options.yaml
index 108d1058..9a7b6b26 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -1 +1,6 @@
 include: package:pedantic/analysis_options.yaml
+
+analyzer:
+  errors:
+    todo: ignore
+    omit_local_variable_types: ignore
\ No newline at end of file
diff --git a/lib/data/local/data_source.dart b/lib/data/local/data_source.dart
index 8f45935b..b8e051e1 100644
--- a/lib/data/local/data_source.dart
+++ b/lib/data/local/data_source.dart
@@ -1,7 +1,8 @@
+import 'package:openflutterecommerce/domain/entities/entity.dart';
 import 'package:path/path.dart';
 import 'package:sqflite/sqflite.dart';
+
 import 'config.dart';
-import 'package:openflutterecommerce/domain/entities/entity.dart';
 
 abstract class DataSource {
   Database db;
@@ -85,7 +86,7 @@ abstract class DataSource {
     await db.close();
   }
 
-  checkDatabaseConnection() {
+  void checkDatabaseConnection() {
     if (db == null) {
       throw Exception(
           'No open connection to database - call .open() on the datasource to establish a connection to the database');
diff --git a/lib/domain/entities/entity.dart b/lib/domain/entities/entity.dart
index e4d29b6d..28e662a1 100644
--- a/lib/domain/entities/entity.dart
+++ b/lib/domain/entities/entity.dart
@@ -2,12 +2,11 @@ import 'package:equatable/equatable.dart';
 import 'package:flutter/widgets.dart';
 
 @immutable
-abstract class Entity<TKey> extends Equatable{
+abstract class Entity<TKey> extends Equatable {
   final TKey id;
 
   Entity(this.id);
 
-  @override
   Map<String, dynamic> toMap();
 
   @override
diff --git a/test/data/local/all_tests.dart b/test/data/local/all_tests.dart
index c3c74399..888877b7 100644
--- a/test/data/local/all_tests.dart
+++ b/test/data/local/all_tests.dart
@@ -12,6 +12,8 @@ import 'order/order_product_data_source_test.dart'
 import 'order/order_product_parameter_data_source_test.dart'
     as order_product_parameter_data_source_test;
 import 'order/user_order_data_source_test.dart' as user_order_data_source_test;
+import 'product/product2parameter_data_source_test.dart'
+    as product2parameter_data_source_test;
 import 'product/product_category_data_source_test.dart'
     as product_category_data_source_test;
 import 'product/product_data_source_test.dart' as product_data_source_test;
@@ -25,14 +27,12 @@ import 'product/product_review_data_source_test.dart'
     as product_review_data_source_test;
 import 'product/product_review_photo_data_source_test.dart'
     as product_review_photo_data_source_test;
-import 'product/product2parameter_data_source_test.dart'
-    as product2parameter_data_source_test;
 import 'promo/promo_code_data_source_test.dart' as promo_code_data_source_test;
 import 'user/shipping_address_data_source_test.dart'
     as shipping_address_data_source_test;
 import 'user/user_data_source_test.dart' as user_data_source_test;
 
-main(List<String> args) {
+void main(List<String> args) {
   // run tests on all data sources (tables)
   delivery_method_data_source_test.main();
   category_hashtag_data_source_test.main();
diff --git a/test/data/local/cart/product_cart_data_source_test.dart b/test/data/local/cart/product_cart_data_source_test.dart
index edee6e5c..73bb3281 100644
--- a/test/data/local/cart/product_cart_data_source_test.dart
+++ b/test/data/local/cart/product_cart_data_source_test.dart
@@ -53,7 +53,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ProductCartEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: delete a record in productcart table', () async {
@@ -65,7 +65,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ProductCartEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: get all records in productcart table', () async {
diff --git a/test/data/local/delivery/delivery_method_data_source_test.dart b/test/data/local/delivery/delivery_method_data_source_test.dart
index 94cf866c..24d1ad08 100644
--- a/test/data/local/delivery/delivery_method_data_source_test.dart
+++ b/test/data/local/delivery/delivery_method_data_source_test.dart
@@ -50,7 +50,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<DeliveryMethodEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in DeliveryMethod table', () async {
@@ -62,7 +62,7 @@ void main() {
       await dataSource.delete(1);
 
       List<DeliveryMethodEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in DeliveryMethod table', () async {
diff --git a/test/data/local/hashtag/category_hashtag_data_source_test.dart b/test/data/local/hashtag/category_hashtag_data_source_test.dart
index 1c7c0b1c..e68ee729 100644
--- a/test/data/local/hashtag/category_hashtag_data_source_test.dart
+++ b/test/data/local/hashtag/category_hashtag_data_source_test.dart
@@ -50,7 +50,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<CategoryHashTagEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in CategoryHashTag table', () async {
@@ -62,7 +62,7 @@ void main() {
       await dataSource.delete(1);
 
       List<CategoryHashTagEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in CategoryHashTag table', () async {
diff --git a/test/data/local/hashtag/hashtag_data_source_test.dart b/test/data/local/hashtag/hashtag_data_source_test.dart
index 654a3df1..f8ec1b06 100644
--- a/test/data/local/hashtag/hashtag_data_source_test.dart
+++ b/test/data/local/hashtag/hashtag_data_source_test.dart
@@ -62,7 +62,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<HashTagEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in HashTag table', () async {
@@ -76,7 +76,7 @@ void main() {
       await dataSource.delete(1);
 
       List<HashTagEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in HashTag table', () async {
diff --git a/test/data/local/hashtag/product_hashtag_data_source_test.dart b/test/data/local/hashtag/product_hashtag_data_source_test.dart
index 8f500f0e..8b565ad2 100644
--- a/test/data/local/hashtag/product_hashtag_data_source_test.dart
+++ b/test/data/local/hashtag/product_hashtag_data_source_test.dart
@@ -50,7 +50,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ProductHashTagEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in ProductHashTag table', () async {
@@ -62,7 +62,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ProductHashTagEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in ProductHashTag table', () async {
diff --git a/test/data/local/order/order_product_data_source_test.dart b/test/data/local/order/order_product_data_source_test.dart
index e0f86789..f9d80d62 100644
--- a/test/data/local/order/order_product_data_source_test.dart
+++ b/test/data/local/order/order_product_data_source_test.dart
@@ -86,7 +86,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<OrderProductEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in OrderProduct table', () async {
@@ -104,7 +104,7 @@ void main() {
       await dataSource.delete(1);
 
       List<OrderProductEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in OrderProduct table', () async {
diff --git a/test/data/local/order/order_product_parameter_data_source_test.dart b/test/data/local/order/order_product_parameter_data_source_test.dart
index 34b43c1b..30626e52 100644
--- a/test/data/local/order/order_product_parameter_data_source_test.dart
+++ b/test/data/local/order/order_product_parameter_data_source_test.dart
@@ -55,7 +55,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<OrderProductParameterEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in OrderProductParameter table', () async {
@@ -67,7 +67,7 @@ void main() {
       await dataSource.delete(1);
 
       List<OrderProductParameterEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in OrderProductParameter table', () async {
diff --git a/test/data/local/order/user_order_data_source_test.dart b/test/data/local/order/user_order_data_source_test.dart
index ce1e7884..a1e692f5 100644
--- a/test/data/local/order/user_order_data_source_test.dart
+++ b/test/data/local/order/user_order_data_source_test.dart
@@ -116,7 +116,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<UserOrderEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in UserOrder table', () async {
@@ -139,7 +139,7 @@ void main() {
       await dataSource.delete(1);
 
       List<UserOrderEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in UserOrder table', () async {
diff --git a/test/data/local/product/product2parameter_data_source_test.dart b/test/data/local/product/product2parameter_data_source_test.dart
index e27b1926..a34969d6 100644
--- a/test/data/local/product/product2parameter_data_source_test.dart
+++ b/test/data/local/product/product2parameter_data_source_test.dart
@@ -69,7 +69,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<Product2ParameterEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: delete a record in product2parameter table', () async {
@@ -84,7 +84,7 @@ void main() {
       await dataSource.delete(1);
 
       List<Product2ParameterEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: get all records in product2parameter table', () async {
diff --git a/test/data/local/product/product_category_data_source_test.dart b/test/data/local/product/product_category_data_source_test.dart
index bf01abc9..70c5b162 100644
--- a/test/data/local/product/product_category_data_source_test.dart
+++ b/test/data/local/product/product_category_data_source_test.dart
@@ -80,7 +80,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ProductCategoryEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in ProductCategory table', () async {
@@ -97,7 +97,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ProductCategoryEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in ProductCategory table', () async {
diff --git a/test/data/local/product/product_data_source_test.dart b/test/data/local/product/product_data_source_test.dart
index 6a423f31..a2141409 100644
--- a/test/data/local/product/product_data_source_test.dart
+++ b/test/data/local/product/product_data_source_test.dart
@@ -147,7 +147,7 @@ void main() {
       await productDataSource.deleteAll();
 
       List<ProductEntity> allProducts = await productDataSource.all();
-      expect(allProducts.length == 0, true);
+      expect(allProducts.isEmpty, true);
     });
 
     test('test: delete a product', () async {
@@ -175,7 +175,7 @@ void main() {
       await productDataSource.delete(1);
 
       List<ProductEntity> allProducts = await productDataSource.all();
-      expect(allProducts.length == 0, true);
+      expect(allProducts.isEmpty, true);
     });
 
     test('test: get all products', () async {
diff --git a/test/data/local/product/product_image_data_source_test.dart b/test/data/local/product/product_image_data_source_test.dart
index 9c97b80b..168742a5 100644
--- a/test/data/local/product/product_image_data_source_test.dart
+++ b/test/data/local/product/product_image_data_source_test.dart
@@ -74,7 +74,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ProductImageEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in ProductImage table', () async {
@@ -90,7 +90,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ProductImageEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in ProductImage table', () async {
@@ -118,7 +118,7 @@ void main() {
       List<ProductImageEntity> allRecords = await dataSource.all();
       expect(allRecords.length == 3, true);
     });
-    
+
     tearDown(() async {
       await dataSource.close();
     });
diff --git a/test/data/local/product/product_parameter_data_source_test.dart b/test/data/local/product/product_parameter_data_source_test.dart
index ee7657b0..90d4724c 100644
--- a/test/data/local/product/product_parameter_data_source_test.dart
+++ b/test/data/local/product/product_parameter_data_source_test.dart
@@ -63,7 +63,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ProductParameterEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in ProductParameter table', () async {
@@ -77,7 +77,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ProductParameterEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in ProductParameter table', () async {
diff --git a/test/data/local/product/product_parameter_variant_data_source_test.dart b/test/data/local/product/product_parameter_variant_data_source_test.dart
index d8c8c287..a146d01a 100644
--- a/test/data/local/product/product_parameter_variant_data_source_test.dart
+++ b/test/data/local/product/product_parameter_variant_data_source_test.dart
@@ -79,7 +79,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ProductParameterVariantEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in ProductParameterVariant table', () async {
@@ -95,7 +95,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ProductParameterVariantEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in ProductParameterVariant table', () async {
diff --git a/test/data/local/product/product_review_data_source_test.dart b/test/data/local/product/product_review_data_source_test.dart
index ae7c5e0e..3e4dd1f4 100644
--- a/test/data/local/product/product_review_data_source_test.dart
+++ b/test/data/local/product/product_review_data_source_test.dart
@@ -98,7 +98,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ProductReviewEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in ProductReview table', () async {
@@ -118,7 +118,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ProductReviewEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in ProductReview table', () async {
diff --git a/test/data/local/product/product_review_photo_data_source_test.dart b/test/data/local/product/product_review_photo_data_source_test.dart
index c993cf7b..632f6405 100644
--- a/test/data/local/product/product_review_photo_data_source_test.dart
+++ b/test/data/local/product/product_review_photo_data_source_test.dart
@@ -69,7 +69,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ProductReviewPhotoEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: delete a record in ProductReviewPhoto table', () async {
@@ -84,7 +84,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ProductReviewPhotoEntity> allRecords = await dataSource.all();
-      expect(allRecords.length == 0, true);
+      expect(allRecords.isEmpty, true);
     });
 
     test('test: get all records in ProductReviewPhoto table', () async {
diff --git a/test/data/local/promo/promo_code_data_source_test.dart b/test/data/local/promo/promo_code_data_source_test.dart
index 4f9cde29..c0e7acae 100644
--- a/test/data/local/promo/promo_code_data_source_test.dart
+++ b/test/data/local/promo/promo_code_data_source_test.dart
@@ -86,7 +86,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<PromoCodeEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: delete a record in promocode table', () async {
@@ -104,7 +104,7 @@ void main() {
       await dataSource.delete(1);
 
       List<PromoCodeEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: get all records in promocode table', () async {
diff --git a/test/data/local/user/shipping_address_data_source_test.dart b/test/data/local/user/shipping_address_data_source_test.dart
index eea5c5e5..f705385a 100644
--- a/test/data/local/user/shipping_address_data_source_test.dart
+++ b/test/data/local/user/shipping_address_data_source_test.dart
@@ -86,7 +86,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<ShippingAddressEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: delete a record in shippingaddress table', () async {
@@ -103,7 +103,7 @@ void main() {
       await dataSource.delete(1);
 
       List<ShippingAddressEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: get all records in shippingaddress table', () async {
diff --git a/test/data/local/user/user_data_source_test.dart b/test/data/local/user/user_data_source_test.dart
index c15ee738..e7fce7e4 100644
--- a/test/data/local/user/user_data_source_test.dart
+++ b/test/data/local/user/user_data_source_test.dart
@@ -98,7 +98,7 @@ void main() {
       await dataSource.deleteAll();
 
       List<UserEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: delete a record in user table', () async {
@@ -118,7 +118,7 @@ void main() {
       await dataSource.delete(1);
 
       List<UserEntity> allData = await dataSource.all();
-      expect(allData.length == 0, true);
+      expect(allData.isEmpty, true);
     });
 
     test('test: get all records in user table', () async {
diff --git a/test/tests.dart b/test/tests.dart
index 0e0382c1..8009af7a 100644
--- a/test/tests.dart
+++ b/test/tests.dart
@@ -1,6 +1,5 @@
 import '../test/data/local/all_tests.dart' as local_database_test;
 
-
-main(List<String> args) {
+void main(List<String> args) {
   local_database_test.main(args);
-}
\ No newline at end of file
+}