S3 - Return default content type (#4439)

moto/s3/models.py

@@ -25,6 +25,7 @@ from moto.core.utils import (
 )
 from moto.cloudwatch.models import MetricDatum
 from moto.utilities.tagging_service import TaggingService
+from moto.utilities.utils import LowercaseDict
 from moto.s3.exceptions import (
     AccessDeniedByLock,
     BucketAlreadyExists,
@@ -113,7 +114,7 @@ class FakeKey(BaseModel):
         self.acl = get_canned_acl("private")
         self.website_redirect_location = None
         self._storage_class = storage if storage else "STANDARD"
-        self._metadata = {}
+        self._metadata = LowercaseDict()
         self._expiry = None
         self._etag = etag
         self._version_id = version_id
@@ -136,6 +137,9 @@ class FakeKey(BaseModel):
         self.lock_legal_status = lock_legal_status
         self.lock_until = lock_until
 
+        # Default metadata values
+        self._metadata["Content-Type"] = "binary/octet-stream"
+
     @property
     def version_id(self):
         return self._version_id

moto/utilities/utils.py

@@ -4,6 +4,9 @@ import string
 import pkgutil
 
 
+from collections.abc import MutableMapping
+
+
 def str2bool(v):
     if v in ("yes", True, "true", "True", "TRUE", "t", "1"):
         return True
@@ -52,3 +55,32 @@ def filter_resources(resources, filters, attr_pairs):
                     result.remove(resource)
                     break
     return result
+
+
+class LowercaseDict(MutableMapping):
+    """A dictionary that lowercases all keys"""
+
+    def __init__(self, *args, **kwargs):
+        self.store = dict()
+        self.update(dict(*args, **kwargs))  # use the free update to set keys
+
+    def __getitem__(self, key):
+        return self.store[self._keytransform(key)]
+
+    def __setitem__(self, key, value):
+        self.store[self._keytransform(key)] = value
+
+    def __delitem__(self, key):
+        del self.store[self._keytransform(key)]
+
+    def __iter__(self):
+        return iter(self.store)
+
+    def __len__(self):
+        return len(self.store)
+
+    def __repr__(self):
+        return str(self.store)
+
+    def _keytransform(self, key):
+        return key.lower()

tests/test_s3/test_s3.py

@@ -6468,3 +6468,21 @@ def test_delete_objects_with_empty_keyname():
 
     client.delete_object(Bucket=bucket_name, Key=key_name)
     client.list_objects(Bucket=bucket_name).shouldnt.have.key("Contents")
+
+
+@mock_s3
+def test_head_object_should_return_default_content_type():
+    s3 = boto3.resource("s3", region_name="us-east-1")
+    s3.create_bucket(Bucket="testbucket")
+    s3.Bucket("testbucket").upload_fileobj(BytesIO(b"foobar"), Key="testobject")
+    s3_client = boto3.client("s3", region_name="us-east-1")
+    resp = s3_client.head_object(Bucket="testbucket", Key="testobject")
+
+    resp["ContentType"].should.equal("binary/octet-stream")
+    resp["ResponseMetadata"]["HTTPHeaders"]["content-type"].should.equal(
+        "binary/octet-stream"
+    )
+
+    s3.Object("testbucket", "testobject").content_type.should.equal(
+        "binary/octet-stream"
+    )