Dart fix template tests (#4015)

* Clean up samples directory before fixing tests

- removed from samples/client/petstore/dart2 :
  - purge_test.sh (doesn't seem to be used and not helpful)
  - openapi folder (is to be re-generated with more meaningful name)
- updated dart2-petstore.sh to generate client library with new name
- used updated shell script to re-generate client library
- updated CI/.drone.yml to use the new client library for tests

* Update petstore tests to use faked http client

- skipped all of the tests that hit a live endpoint
- made a fake http client that can be set to check for expected values
   and/or return a provided response
- added some files with test data recorded from live api calls
- updated the README to reflect changes to tests

* Update .drone.yml so CI will run the tests

Author: nickmeinhold

CI/.drone.yml

@@ -13,7 +13,7 @@ steps:
   commands:
   - (cd samples/client/petstore/dart-jaguar/openapi && pub get && pub run build_runner build --delete-conflicting-outputs)
   - (cd samples/client/petstore/dart-jaguar/flutter_petstore/openapi && pub get && pub run build_runner build --delete-conflicting-outputs)
-  - (cd samples/client/petstore/dart2/openapi && pub get && pub run test)
+  - (cd samples/client/petstore/dart2/petstore && pub get && pub run test)
 # test Java 11 HTTP client
 - name: java11-test
   image: openjdk:11.0

bin/dart2-petstore.sh

@@ -29,5 +29,5 @@ fi
 export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
 
 # Generate client
-ags="generate -t modules/openapi-generator/src/main/resources/dart2 -i modules/openapi-generator/src/test/resources/2_0/petstore.yaml -g dart -o samples/client/petstore/dart2/openapi --additional-properties hideGenerationTimestamp=true  $@"
+ags="generate -t modules/openapi-generator/src/main/resources/dart2 -i modules/openapi-generator/src/test/resources/2_0/petstore.yaml -g dart -o samples/client/petstore/dart2/petstore_client_lib --additional-properties hideGenerationTimestamp=true $@"
 java $JAVA_OPTS -jar $executable $ags

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

@@ -1,3 +1,29 @@
+# Background 
+
+## Current state of tests 
+
+TL;DR currently the only tests are e2e tests that were adapted to use a faked http client. While pushing data around as a smoke test has some value, more testing is required. In particular we need comprehensive unit/integration tests.
+
+- an old set of e2e tests are skipped for CI, as they hit a live endpoint and so are inherently flaky 
+  - `pet_test.dart`
+  - `store_test.dart`
+  - `user_test.dart`
+- the above set of tests were adapted to use a faked http client 
+  - the tests are not really well suited to being used with a stubbed client, many are basically just testing the endpoint logic
+  - while not a great set of tests, they do have some value as a smoke test for template changes
+- the adapted tests and files that contain test data:
+  - `pet_test_fake_client.dart` 
+  - `store_test_fake_client.dart`
+  - `user_test_fake_client.dart`
+  - `fake_client.dart`
+  - `file_upload_response.json`
+
+## Assumptions 
+
+- the tests will be run as part of CI and so have access to dart:io 
+
+# Running 
+
 ## If not already done, resolve dependencies
 
 `pub get`
@@ -8,4 +34,4 @@
 
 ## To run all tests in the test folder:
 
-`pub run test test`
+`pub run test`