[dart2] Fix up test code generation, double deserialization, 'new' keyword deprecation (#3576)

* dart2: Use the correct classname in test generation

At present test generation has a stray hard-coded reference to the pet
store Pet() class, which should reflect the actual classname under test.

* dart2: Call toDouble() in generated code for double types

At present the generated code does not correctly handle transitioning
to double when dealing with non-integer types in JSON deserialization.
This ends up with dart raising an unhandled type mismatch exception:

Unhandled exception: type 'int' is not a subtype of type 'double' where
...

Using the .toDouble() conversion when a double type is expected fixes
this up by making the typing explicit.

* dart2: Drop use of deprecated 'new' keyword in generated code

The use of the 'new' keyword in dart2 is deprecated and should be
avoided, as per the official guidance of the dart2 authors:

https://dart.dev/guides/language/effective-dart/usage#dont-use-new

* dart2: Regenerate samples for mustache template changes

Author: pmundt

modules/openapi-generator/src/main/resources/dart2/README.mustache

@@ -74,9 +74,9 @@ import 'package:{{pubName}}/api.dart';
 {{/authMethods}}
 {{/hasAuthMethods}}
 
-var api_instance = new {{classname}}();
+var api_instance = {{classname}}();
 {{#allParams}}
-var {{paramName}} = {{#isListContainer}}[{{/isListContainer}}{{#isBodyParam}}new {{dataType}}(){{/isBodyParam}}{{^isBodyParam}}{{{example}}}{{/isBodyParam}}{{#isListContainer}}]{{/isListContainer}}; // {{{dataType}}} | {{{description}}}
+var {{paramName}} = {{#isListContainer}}[{{/isListContainer}}{{#isBodyParam}}{{dataType}}(){{/isBodyParam}}{{^isBodyParam}}{{{example}}}{{/isBodyParam}}{{#isListContainer}}]{{/isListContainer}}; // {{{dataType}}} | {{{description}}}
 {{/allParams}}
 
 try {

modules/openapi-generator/src/main/resources/dart2/api.mustache

@@ -19,7 +19,7 @@ class {{classname}} {
     {{#allParams}}
       {{#required}}
     if({{paramName}} == null) {
-     throw new ApiException(400, "Missing required param: {{paramName}}");
+     throw ApiException(400, "Missing required param: {{paramName}}");
     }
       {{/required}}
     {{/allParams}}
@@ -51,7 +51,7 @@ class {{classname}} {
 
     if(contentType.startsWith("multipart/form-data")) {
       bool hasFields = false;
-      MultipartRequest mp = new MultipartRequest(null, null);
+      MultipartRequest mp = MultipartRequest(null, null);
       {{#formParams}}
       {{^isFile}}
       if ({{paramName}} != null) {
@@ -89,7 +89,7 @@ class {{classname}} {
                                              authNames);
 
     if(response.statusCode >= 400) {
-      throw new ApiException(response.statusCode, _decodeBodyBytes(response));
+      throw ApiException(response.statusCode, _decodeBodyBytes(response));
     } else if(response.body != null) {
       {{#isListContainer}}
         {{#returnType}}
@@ -99,7 +99,7 @@ class {{classname}} {
       {{^isListContainer}}
         {{#isMapContainer}}
           {{#returnType}}
-      return new {{{returnType}}}.from(apiClient.deserialize(_decodeBodyBytes(response), '{{{returnType}}}'));
+      return {{{returnType}}}.from(apiClient.deserialize(_decodeBodyBytes(response), '{{{returnType}}}'));
           {{/returnType}};
         {{/isMapContainer}}
         {{^isMapContainer}}

modules/openapi-generator/src/main/resources/dart2/api_doc.mustache

@@ -45,9 +45,9 @@ import 'package:{{pubName}}/api.dart';
 {{/authMethods}}
 {{/hasAuthMethods}}
 
-var api_instance = new {{classname}}();
+var api_instance = {{classname}}();
 {{#allParams}}
-var {{paramName}} = {{#isListContainer}}[{{/isListContainer}}{{#isBodyParam}}new {{dataType}}(){{/isBodyParam}}{{^isBodyParam}}{{{example}}}{{/isBodyParam}}{{#isListContainer}}]{{/isListContainer}}; // {{{dataType}}} | {{{description}}}
+var {{paramName}} = {{#isListContainer}}[{{/isListContainer}}{{#isBodyParam}}{{dataType}}(){{/isBodyParam}}{{^isBodyParam}}{{{example}}}{{/isBodyParam}}{{#isListContainer}}]{{/isListContainer}}; // {{{dataType}}} | {{{description}}}
 {{/allParams}}
 
 try { 

modules/openapi-generator/src/main/resources/dart2/api_test.mustache

@@ -5,7 +5,7 @@ import 'package:test/test.dart';
 
 /// tests for {{classname}}
 void main() {
-  var instance = new {{classname}}();
+  var instance = {{classname}}();
 
   group('tests for {{classname}}', () {
     {{#operation}}

modules/openapi-generator/src/main/resources/dart2/class.mustache

@@ -36,7 +36,7 @@ class {{classname}} {
       {{name}} = {{complexType}}.mapFromJson(json['{{baseName}}']);
       {{/isMapContainer}}
       {{^isMapContainer}}
-      {{name}} = new {{complexType}}.fromJson(json['{{baseName}}']);
+      {{name}} = {{complexType}}.fromJson(json['{{baseName}}']);
       {{/isMapContainer}}
       {{/isListContainer}}
     {{/complexType}}
@@ -49,7 +49,12 @@ class {{classname}} {
           {{name}} = (json['{{baseName}}'] as Map).cast<String, {{items.datatype}}>();
         {{/isMapContainer}}
         {{^isMapContainer}}
+	{{#isDouble}}
+          {{name}} = json['{{baseName}}'].toDouble();
+	{{/isDouble}}
+	{{^isDouble}}
           {{name}} = json['{{baseName}}'];
+	{{/isDouble}}
         {{/isMapContainer}}
       {{/isListContainer}}
     {{/complexType}}
@@ -81,13 +86,13 @@ class {{classname}} {
   }
 
   static List<{{classname}}> listFromJson(List<dynamic> json) {
-    return json == null ? new List<{{classname}}>() : json.map((value) => new {{classname}}.fromJson(value)).toList();
+    return json == null ? List<{{classname}}>() : json.map((value) => {{classname}}.fromJson(value)).toList();
   }
 
   static Map<String, {{classname}}> mapFromJson(Map<String, dynamic> json) {
-    var map = new Map<String, {{classname}}>();
+    var map = Map<String, {{classname}}>();
     if (json != null && json.isNotEmpty) {
-      json.forEach((String key, dynamic value) => map[key] = new {{classname}}.fromJson(value));
+      json.forEach((String key, dynamic value) => map[key] = {{classname}}.fromJson(value));
     }
     return map;
   }

modules/openapi-generator/src/main/resources/dart2/model_test.mustache

@@ -5,7 +5,7 @@ import 'package:test/test.dart';
 
 // tests for {{classname}}
 void main() {
-  var instance = new Pet();
+  var instance = {{classname}}();
 
   group('test {{classname}}', () {
     {{#vars}}

samples/client/petstore/dart/flutter_petstore/openapi/.openapi-generator/VERSION

@@ -1 +1 @@
-4.0.1-SNAPSHOT
+4.1.0-SNAPSHOT

samples/client/petstore/dart/flutter_petstore/openapi/.travis.yml

@@ -3,7 +3,7 @@
 language: dart
 dart:
 # Install a specific stable release
-- "1.24.3"
+- "2.2.0"
 install:
 - pub get
 

samples/client/petstore/dart/flutter_petstore/openapi/README.md

@@ -44,13 +44,13 @@ Please follow the [installation procedure](#installation--usage) and then run th
 import 'package:openapi/api.dart';
 
 // TODO Configure OAuth2 access token for authorization: petstore_auth
-//openapi.api.Configuration.accessToken = 'YOUR_ACCESS_TOKEN';
+//defaultApiClient.getAuthentication<OAuth>('petstore_auth').accessToken = 'YOUR_ACCESS_TOKEN';
 
-var api_instance = new PetApi();
-var body = new Pet(); // Pet | Pet object that needs to be added to the store
+var api_instance = PetApi();
+var pet = Pet(); // Pet | Pet object that needs to be added to the store
 
 try {
-    api_instance.addPet(body);
+    api_instance.addPet(pet);
 } catch (e) {
     print("Exception when calling PetApi->addPet: $e\n");
 }
@@ -89,6 +89,8 @@ Class | Method | HTTP request | Description
 
  - [ApiResponse](docs//ApiResponse.md)
  - [Category](docs//Category.md)
+ - [InlineObject](docs//InlineObject.md)
+ - [InlineObject1](docs//InlineObject1.md)
  - [Order](docs//Order.md)
  - [Pet](docs//Pet.md)
  - [Tag](docs//Tag.md)
@@ -104,6 +106,12 @@ Class | Method | HTTP request | Description
 - **API key parameter name**: api_key
 - **Location**: HTTP header
 
+## auth_cookie
+
+- **Type**: API key
+- **API key parameter name**: AUTH_KEY
+- **Location**: 
+
 ## petstore_auth
 
 - **Type**: OAuth

samples/client/petstore/dart/flutter_petstore/openapi/docs/InlineObject.md

@@ -0,0 +1,16 @@
+# openapi.model.InlineObject
+
+## Load the model package
+```dart
+import 'package:openapi/api.dart';
+```
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**name** | **String** | Updated name of the pet | [optional] [default to null]
+**status** | **String** | Updated status of the pet | [optional] [default to null]
+
+[[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
+
+