[Storage] Update kms samples (GoogleCloudPlatform#1517)

* Storage: add KMS samples

* Add CLOUD_KMS_KEY environment variable

* Add region tags around samples

* Add more testing

* Fix tests and lint

Author: frankyn

storage/cloud-client/snippets.py

@@ -44,6 +44,7 @@ def delete_bucket(bucket_name):
 
 
 def enable_default_kms_key(bucket_name, kms_key_name):
+    # [START storage_set_bucket_default_kms_key]
     """Sets a bucket's default KMS key."""
     storage_client = storage.Client()
     bucket = storage_client.get_bucket(bucket_name)
@@ -53,6 +54,7 @@ def enable_default_kms_key(bucket_name, kms_key_name):
     print('Set default KMS key for bucket {} to {}.'.format(
         bucket.name,
         bucket.default_kms_key_name))
+    # [END storage_set_bucket_default_kms_key]
 
 
 def get_bucket_labels(bucket_name):
@@ -157,6 +159,7 @@ def upload_blob(bucket_name, source_file_name, destination_blob_name):
 
 def upload_blob_with_kms(bucket_name, source_file_name, destination_blob_name,
                          kms_key_name):
+    # [START storage_upload_with_kms_key]
     """Uploads a file to the bucket, encrypting it with the given KMS key."""
     storage_client = storage.Client()
     bucket = storage_client.get_bucket(bucket_name)
@@ -167,6 +170,7 @@ def upload_blob_with_kms(bucket_name, source_file_name, destination_blob_name,
         source_file_name,
         destination_blob_name,
         kms_key_name))
+    # [END storage_upload_with_kms_key]
 
 
 def download_blob(bucket_name, source_blob_name, destination_file_name):

storage/cloud-client/snippets_test.py

@@ -26,6 +26,16 @@
 KMS_KEY = os.environ['CLOUD_KMS_KEY']
 
 
+def test_enable_default_kms_key():
+    snippets.enable_default_kms_key(
+        bucket_name=BUCKET,
+        kms_key_name=KMS_KEY)
+    bucket = storage.Client().get_bucket(BUCKET)
+    assert bucket.default_kms_key_name.startswith(KMS_KEY)
+    bucket.default_kms_key_name = None
+    bucket.patch()
+
+
 def test_get_bucket_labels():
     snippets.get_bucket_labels(BUCKET)
 
@@ -83,12 +93,14 @@ def test_upload_blob():
 def test_upload_blob_with_kms():
     with tempfile.NamedTemporaryFile() as source_file:
         source_file.write(b'test')
-
         snippets.upload_blob_with_kms(
             BUCKET,
             source_file.name,
             'test_upload_blob_encrypted',
             KMS_KEY)
+        bucket = storage.Client().bucket(BUCKET)
+        kms_blob = bucket.get_blob('test_upload_blob_encrypted')
+        assert kms_blob.kms_key_name.startswith(KMS_KEY)
 
 
 def test_download_blob(test_blob):