[Dart] Fix README template and update testing doco (OpenAPITools#3809)

* [Dart] Fix README template and update testing doco

- deleted redundant shell script
- fixed and updated README template
- updated test package and moved to a dev_dependency
- removed old unused dev_dependency packages
- updated testing documentation in petstore sample

* Remove references to dart-flutter-petstore.sh

* Fix typos

* Fix typo

.github/.test/samples.json

@@ -145,12 +145,6 @@
         "Documentation: Cwiki"
       ]
     },
-    {
-      "input": "dart-flutter-petstore.sh",
-      "matches": [
-        "Client: Dart"
-      ]
-    },
     {
       "input": "dart-jaguar-petstore.sh",
       "matches": [

bin/utils/ensure-up-to-date

@@ -59,7 +59,6 @@ declare -a scripts=(
 "./bin/apex-petstore.sh"
 "./bin/perl-petstore-all.sh"
 "./bin/dart-jaguar-petstore.sh"
-"./bin/dart-flutter-petstore.sh"
 "./bin/dart-petstore.sh"
 "./bin/dart2-petstore.sh"
 "./bin/java-play-framework-petstore-server-all.sh"

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

@@ -19,24 +19,20 @@ For more information, please visit [{{{infoUrl}}}]({{{infoUrl}}})
 
 ## Requirements
 
-Dart 1.20.0 or later OR Flutter 0.0.20 or later
+Dart 2.0 or later
 
 ## Installation & Usage
 
 ### Github
-If this Dart package is published to Github, please include the following in pubspec.yaml
+If this Dart package is published to Github, add the following dependency to your pubspec.yaml
 ```
-name: {{pubName}}
-version: {{pubVersion}}
-description: {{pubDescription}}
 dependencies:
   {{pubName}}:
     git: https://github.com/{{gitUserId}}/{{gitRepoId}}.git
-      version: 'any'
 ```
 
 ### Local
-To use the package in your local drive, please include the following in pubspec.yaml
+To use the package in your local drive, add the following dependency to your pubspec.yaml
 ```
 dependencies:
   {{pubName}}:

samples/client/petstore/dart2/openapi/README.md

@@ -8,24 +8,20 @@ This Dart package is automatically generated by the [OpenAPI Generator](https://
 
 ## Requirements
 
-Dart 1.20.0 or later OR Flutter 0.0.20 or later
+Dart 2.0 or later
 
 ## Installation & Usage
 
 ### Github
-If this Dart package is published to Github, please include the following in pubspec.yaml
+If this Dart package is published to Github, add the following dependency to your pubspec.yaml
 ```
-name: openapi
-version: 1.0.0
-description: OpenAPI API client
 dependencies:
   openapi:
     git: https://github.com/GIT_USER_ID/GIT_REPO_ID.git
-      version: 'any'
 ```
 
 ### Local
-To use the package in your local drive, please include the following in pubspec.yaml
+To use the package in your local drive, add the following dependency to your pubspec.yaml
 ```
 dependencies:
   openapi:

samples/client/petstore/dart2/petstore/README.md

@@ -1,58 +1,11 @@
-# To run these tests:
+## If not already done, resolve dependencies
 
-Simply start the dart server: `pub serve`
+`pub get`
 
-then open http://127.0.0.1:8080/tests.html
+## To run tests in a single file:
 
+`pub run test test/pet_test.dart`
 
-This already starts the tests.  There is _NO_ feedback!
+## To run all tests in the test folder:
 
-Open the javascript / dart console of your browser to verify all tests 
-passed successfully.
-
-You should have the following output:
-```
-Observatory listening at http://127.0.0.1:39067/
-unittest-suite-wait-for-done
-GET http://petstore.swagger.io/v2/pet/957639 404 (Not Found)
-GET http://petstore.swagger.io/v2/pet/525946 404 (Not Found)
-GET http://petstore.swagger.io/v2/store/order/29756 404 (Not Found)
-GET http://petstore.swagger.io/v2/user/Riddlem325 404 (Not Found)
-PASS: Pet API  adds a new pet and gets it by id
-PASS: Pet API  doesn't get non-existing pet by id
-PASS: Pet API  deletes existing pet by id
-PASS: Pet API  updates pet with form
-PASS: Pet API  updates existing pet
-PASS: Pet API  finds pets by status
-PASS: Pet API  finds pets by tag
-PASS: Pet API  uploads a pet image
-PASS: Store API  places an order and gets it by id
-PASS: Store API  deletes an order
-PASS: Store API  gets the store inventory
-PASS: User API  creates a user
-PASS: User API  creates users with list input
-PASS: User API  updates a user
-PASS: User API  deletes a user
-PASS: User API  logs a user in
-
-All 16 tests passed.
-unittest-suite-success
-```
-
-
-You may also run the tests in the dart vm.
-
-Either generate the test-package for a vm:
-- change bin/dart-petstore.sh and uncomment the vm options line
-- run bin/dart-petstore.sh
-
-or
-
-- in `lib/api_client.dart` change `new BrowserClient()` to `new Client()`
-- in `lib/api.dart` remove the line `import 'package:http/browser_client.dart';`
-
-
-
-Then run `test/tests.dart`.
-
-Have fun.
+`pub run test test`

samples/client/petstore/dart2/petstore/pubspec.yaml

@@ -6,8 +6,5 @@ environment:
 dependencies:
   openapi:
     path: ../openapi
-  test: ^1.3.0
 dev_dependencies:
-  build_runner: ^0.10.1+1
-  build_test: ^0.10.3+1
-  build_web_compilers: ^0.4.2+2
+  test: ^1.6.8