Break out MissingKey as separate exception. Closes #571.

moto/s3/exceptions.py

@@ -6,6 +6,10 @@ ERROR_WITH_BUCKET_NAME = """{% extends 'error' %}
 {% block extra %}<BucketName>{{ bucket }}</BucketName>{% endblock %}
 """
 
+ERROR_WITH_KEY_NAME = """{% extends 'error' %}
+{% block extra %}<KeyName>{{ key_name }}</KeyName>{% endblock %}
+"""
+
 
 class S3ClientError(RESTError):
     pass
@@ -40,6 +44,17 @@ class MissingBucket(BucketError):
             *args, **kwargs)
 
 
+class MissingKey(S3ClientError):
+    code = 404
+
+    def __init__(self, key_name):
+        super(MissingKey, self).__init__(
+            "NoSuchKey",
+            "The specified key does not exist.",
+            Key=key_name,
+        )
+
+
 class InvalidPartOrder(S3ClientError):
     code = 400
 

moto/s3/models.py

@@ -11,7 +11,7 @@ import six
 from bisect import insort
 from moto.core import BaseBackend
 from moto.core.utils import iso_8601_datetime_with_milliseconds, rfc_1123_datetime
-from .exceptions import BucketAlreadyExists, MissingBucket, InvalidPart, EntityTooSmall
+from .exceptions import BucketAlreadyExists, MissingBucket, MissingKey, InvalidPart, EntityTooSmall
 from .utils import clean_key_name, _VersionedKeyStore
 
 UPLOAD_ID_BYTES = 43
@@ -393,11 +393,13 @@ class S3Backend(BaseBackend):
         bucket = self.get_bucket(bucket_name)
         if bucket:
             if version_id is None:
-                return bucket.keys.get(key_name)
+                if key_name in bucket.keys:
+                    return bucket.keys[key_name]
             else:
                 for key in bucket.keys.getlist(key_name):
                     if str(key._version_id) == str(version_id):
                         return key
+        raise MissingKey(key_name=key_name)
 
     def initiate_multipart(self, bucket_name, key_name, metadata):
         bucket = self.get_bucket(bucket_name)

moto/s3/responses.py

@@ -399,11 +399,8 @@ class ResponseObject(_TemplateEnvironmentMixin):
             template = self.response_template(S3_OBJECT_ACL_RESPONSE)
             return 200, headers, template.render(obj=key)
 
-        if key:
-            headers.update(key.metadata)
-            return 200, headers, key.value
-        else:
-            return 404, headers, ""
+        headers.update(key.metadata)
+        return 200, headers, key.value
 
     def _key_response_put(self, request, body, bucket_name, query, key_name, headers):
         if query.get('uploadId') and query.get('partNumber'):