null safety migration

Migrate for null safety.

Closes adaptant-labs#5.

example/vin_decoder_example.dart

@@ -10,7 +10,7 @@ void main() async {
   print("Model year is " + vin.modelYear());
   print("Serial number is " + vin.serialNumber());
   print("Assembly plant is " + vin.assemblyPlant());
-  print("Manufacturer is " + vin.getManufacturer());
+  print("Manufacturer is " + vin.getManufacturer()!);
   print("Year is " + vin.getYear().toString());
   print("Region is " + vin.getRegion());
   print("VIN string is " + vin.toString());

lib/src/nhtsa_model.dart

@@ -3,10 +3,10 @@ import 'package:http/http.dart' as http;
 import 'dart:convert';
 
 class NHTSAResult {
-  String value;
-  String valueId;
-  String variable;
-  int variableId;
+  String? value;
+  String? valueId;
+  String? variable;
+  int? variableId;
 
   NHTSAResult({this.value, this.valueId, this.variable, this.variableId});
 
@@ -24,10 +24,10 @@ class NHTSAResult {
 }
 
 class NHTSAVehicleInfo {
-  int count;
-  String message;
-  String searchCriteria;
-  List<NHTSAResult> results;
+  int? count;
+  String? message;
+  String? searchCriteria;
+  List<NHTSAResult>? results;
 
   NHTSAVehicleInfo(
       {this.count, this.message, this.searchCriteria, this.results});
@@ -37,10 +37,10 @@ class NHTSAVehicleInfo {
     message = json['Message'];
     searchCriteria = json['SearchCriteria'];
     if (json['Results'] != null) {
-      results = List<NHTSAResult>();
+      results = [];
       json['Results'].forEach((v) {
         if (v['Value'] != null) {
-          results.add(NHTSAResult.fromJson(v));
+          results!.add(NHTSAResult.fromJson(v));
         }
       });
     }
@@ -54,16 +54,16 @@ class NHTSAVehicleInfo {
   ExtendedVehicleInfo toExtendedVehicleInfo() {
     final ExtendedVehicleInfo info = ExtendedVehicleInfo();
 
-    results.forEach((f) {
+    results!.forEach((f) {
       switch (f.variable) {
         case "Vehicle Type":
-          info.vehicleType = normalizeStringValue(f.value);
+          info.vehicleType = normalizeStringValue(f.value!);
           break;
         case "Make":
-          info.make = normalizeStringValue(f.value);
+          info.make = normalizeStringValue(f.value!);
           break;
         case "Model":
-          info.model = normalizeStringValue(f.value);
+          info.model = normalizeStringValue(f.value!);
           break;
       }
     });
@@ -78,15 +78,15 @@ class NHTSAVehicleInfo {
 }
 
 class ExtendedVehicleInfo {
-  String make;
-  String model;
-  String vehicleType;
+  String? make;
+  String? model;
+  String? vehicleType;
 
-  static Future<ExtendedVehicleInfo> getExtendedVehicleInfo(String vin) async {
-    var path = 'https://vpic.nhtsa.dot.gov/api//vehicles/DecodeVin/' +
+  static Future<ExtendedVehicleInfo?> getExtendedVehicleInfo(String vin) async {
+    var path = 'https://vpic.nhtsa.dot.gov/api/vehicles/DecodeVin/' +
         vin +
         '?format=json';
-    final response = await http.get(path);
+    final response = await http.get(Uri.parse(path));
 
     if (response.statusCode == 200) {
       var vehicleInfo = NHTSAVehicleInfo.fromJson(jsonDecode(response.body));

lib/src/vin_decoder_base.dart

@@ -18,16 +18,16 @@ class VIN {
 
   /// Try to obtain extended information for the VIN from the NHTSA database.
   final bool extended;
-  ExtendedVehicleInfo _info;
+  ExtendedVehicleInfo? _info;
 
-  VIN({@required this.number, this.extended = false})
+  VIN({required this.number, this.extended = false})
       : wmi = normalize(number).substring(0, 3),
         vds = normalize(number).substring(3, 9),
         vis = normalize(number).substring(9, 17);
 
   /// Carry out VIN validation. A valid [number] must be 17 characters long
   /// and contain only valid alphanumeric characters.
-  bool valid([String number]) {
+  bool valid([String? number]) {
     String value = normalize(number != null ? number : this.number);
     return RegExp(r"^[a-zA-Z0-9]+$").hasMatch(value) && value.length == 17;
   }
@@ -37,7 +37,7 @@ class VIN {
       number.toUpperCase().replaceAll('-', '');
 
   /// Obtain the encoded manufacturing year in YYYY format.
-  int getYear() {
+  int? getYear() {
     return yearMap[modelYear()];
   }
 
@@ -65,7 +65,7 @@ class VIN {
   }
 
   /// Get the full name of the vehicle manufacturer as defined by the [wmi].
-  String getManufacturer() {
+  String? getManufacturer() {
     if (manufacturers.containsKey(this.wmi)) {
       return manufacturers[this.wmi];
     } else {
@@ -76,7 +76,7 @@ class VIN {
   /// Returns the checksum for the VIN. Note that in the case of the EU region
   /// checksums are not implemented, so this becomes a no-op. More information
   /// is provided in ISO 3779:2009.
-  String getChecksum() {
+  String? getChecksum() {
     return (getRegion() != "EU") ? normalize(this.number)[8] : null;
   }
 
@@ -98,21 +98,21 @@ class VIN {
 
   /// Get the Make of the vehicle from the NHTSA database if [extended] mode
   /// is enabled.
-  Future<String> getMakeAsync() async {
+  Future<String?> getMakeAsync() async {
     await _fetchExtendedVehicleInfo();
     return this._info?.make;
   }
 
   /// Get the Model of the vehicle from the NHTSA database if [extended] mode
   /// is enabled.
-  Future<String> getModelAsync() async {
+  Future<String?> getModelAsync() async {
     await _fetchExtendedVehicleInfo();
     return this._info?.model;
   }
 
   /// Get the Vehicle Type from the NHTSA database if [extended] mode is
   /// enabled.
-  Future<String> getVehicleTypeAsync() async {
+  Future<String?> getVehicleTypeAsync() async {
     await _fetchExtendedVehicleInfo();
     return this._info?.vehicleType;
   }

pubspec.yaml

@@ -8,13 +8,13 @@ repository: https://github.com/adaptant-labs/vin-decoder-dart
 issue_tracker: https://github.com/adaptant-labs/vin-decoder-dart/issues
 
 environment:
-  sdk: '>=2.1.0 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
-  meta: ^1.2.4
-  basic_utils: ^2.6.3
-  http: ^0.12.2
-  random_string: ^2.1.0
+  meta: ^1.3.0
+  basic_utils: ^3.0.0-nullsafety.0
+  http: ^0.13.0
+  random_string: ^2.2.0-nullsafety
 
 dev_dependencies:
-  test: ^1.15.7
+  test: ^1.16.5

test/vin_decoder_test.dart

@@ -3,7 +3,7 @@ import 'package:test/test.dart';
 
 void main() {
   group('EU VIN Test', () {
-    VIN vin;
+    late VIN vin;
 
     setUp(() {
       vin = VIN(number: 'WP0ZZZ99ZTS392124');
@@ -23,7 +23,7 @@ void main() {
   });
 
   group('AS VIN Test', () {
-    VIN vin;
+    late VIN vin;
 
     setUp(() {
       vin = VIN(number: 'JS1VX51L7X2175460');

test/vin_generator_test.dart

@@ -4,7 +4,7 @@ import 'package:test/test.dart';
 void main() {
   group('VIN Generator Test', () {
     VINGenerator generator;
-    VIN vin;
+    late VIN vin;
 
     setUp(() {
       generator = VINGenerator();