docs: add test scenarios currently supported

Signed-off-by: Anish Ramasekar <anish.ramasekar@gmail.com>

Author: aramase

test/README.md

@@ -0,0 +1,20 @@
+# Testing
+
+This doc lists the different Secrets Store CSI Driver scenarios tested as part of CI.
+
+## E2E tests
+
+| Test Category                                                                                                                                                                                                                                         | Azure | Vault | GCP |
+| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----- | ----- | --- |
+| Mount tests<ul><li>CSI Inline volume test with Pod Portability</li></ul>                                                                                                                                                                              | ✔️     | ✔️     | ✔️   |
+| Sync as Kubernetes secrets<ul><li>Check Kubernetes secret</li><li>Check owner references in secret with multiple owners</li><li>Check owner references updated when a owner is deleted</li><li>Check secret deleted when all owners deleted</li></ul> | ✔️     | ✔️     |     |
+| Namespaced Scope SecretProviderClass<ul><li>Check `SecretProviderClass` in same namespace as pod</li></ul>                                                                                                                                            | ✔️     | ✔️     |     |
+| Namespaced Scope SecretProviderClass negative test<ul><li>Check volume mount fails when `SecretProviderClass` not found in same namespace as pod</li></ul>                                                                                            | ✔️     | ✔️     |     |
+| Multiple SecretProviderClass<ul><li>Check multiple CSI Inline volumes with different SecretProviderClass</li></ul>                                                                                                                                    | ✔️     | ✔️     |     |
+| Autorotation of mount contents and Kubernetes secrets<ul><li>Check mount content and Kubernetes secret updated after rotation</li></ul>                                                                                                               | ✔️     |       |     |
+| Test filtered watch for `nodePublishSecretRef` feature<ul><li>Check labelled nodePublishSecretRef accessible after upgrade to enable `filteredWatchSecret` feature</li></ul>                                                                          | ✔️     |       | ✔️   |
+| Windows tests                                                                                                                                                                                                                                         | ✔️     |       |     |
+
+## Sanity tests
+
+CSI Driver sanity tests using [CSI Driver Sanity Tester](https://github.com/kubernetes-csi/csi-test/tree/master/pkg/sanity#csi-driver-sanity-tester) to ensure Secrets Store CSI Driver conforms to the CSI specification.