docs: Describing how to run acceptance scenario (#817)

Co-authored-by: Rémy Léone <[email protected]>

Author: jeansebastienh

README.md

@@ -45,16 +45,4 @@ $ $GOPATH/bin/terraform-provider-scaleway
 ...
 ```
 
-In order to test the provider, you can simply run `make test`.
-
-```sh
-$ make test
-```
-
-In order to run the full suite of Acceptance tests, run `make testacc`.
-
-*Note:* Acceptance tests create real resources, and often cost money to run.
-
-```sh
-$ make testacc
-```
+Please refer to the [TESTING.md](TESTING.md) for testing.

TESTING.md

@@ -0,0 +1,50 @@
+# Testing the module
+
+## Unit testing
+
+You can test the provider, by running `make test`.
+
+```sh
+make test
+```
+
+## Acceptance testing
+
+Acceptance test are made to test the terraform module with real API calls so they will create real resources that will be invoiced.
+But in order to run faster tests and avoid bad surprise at the end of the month we shipped the project with mocks (recorded with [go-vcr](https://github.com/dnaeon/go-vcr)).
+
+### Running the acceptance tests with mocks
+
+By default, mocks are used during acceptance tests.
+
+```sh
+make testacc
+```
+
+### Running the acceptance tests on real resources
+
+:warning: This will cost money.
+
+```sh
+export TF_UPDATE_CASSETTES=true
+make testacc
+```
+
+It's also required to have Scaleway environment vars available :
+
+```sh
+export SCW_ACCESS_KEY=SCWXXXXXXXXXXXXXXXXX
+export SCW_SECRET_KEY=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
+export SCW_DEFAULT_PROJECT_ID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
+```
+
+To ease debugging you can also set:
+```sh
+export TF_LOG=DEBUG
+export SCW_DEBUG=1
+```
+
+Running a single test:
+```sh
+TF_UPDATE_CASSETTES=true;TF_LOG=DEBUG;SCW_DEBUG=1;TF_ACC=1 go test ./scaleway -v -run=TestAccScalewayDataSourceRDBInstance_Basic -timeout=120m -parallel=10
+```