test Get/HeadObject with partNumber for single-multipart upload

test_multipart_get_part() tests 'normal' multipart uploads. add a new
test case for a multipart upload with a single part to tests the fix
for https://tracker.ceph.com/issues/66705

Signed-off-by: Casey Bodley <cbodley@redhat.com>

s3tests_boto3/functional/test_s3.py

@@ -6458,6 +6458,48 @@ def test_multipart_get_part():
     assert status == 400
     assert error_code == 'InvalidPart'
 
+@pytest.mark.fails_on_dbstore
+def test_multipart_single_get_part():
+    bucket_name = get_new_bucket()
+    client = get_client()
+    key = "mymultipart"
+
+    part_size = 5*1024*1024
+    part_sizes = [part_size] # just one part
+    part_count = len(part_sizes)
+    total_size = sum(part_sizes)
+
+    (upload_id, data, parts) = _multipart_upload(bucket_name, key, total_size, part_size)
+
+    # request part before complete
+    e = assert_raises(ClientError, client.get_object, Bucket=bucket_name, Key=key, PartNumber=1)
+    status, error_code = _get_status_and_error_code(e.response)
+    assert status == 404
+    assert error_code == 'NoSuchKey'
+
+    client.complete_multipart_upload(Bucket=bucket_name, Key=key, UploadId=upload_id, MultipartUpload={'Parts': parts})
+    assert len(parts) == part_count
+
+    for part, size in zip(parts, part_sizes):
+        response = client.head_object(Bucket=bucket_name, Key=key, PartNumber=part['PartNumber'])
+        assert response['PartsCount'] == part_count
+        assert response['ETag'] == '"{}"'.format(part['ETag'])
+
+        response = client.get_object(Bucket=bucket_name, Key=key, PartNumber=part['PartNumber'])
+        assert response['PartsCount'] == part_count
+        assert response['ETag'] == '"{}"'.format(part['ETag'])
+        assert response['ContentLength'] == size
+        # compare contents
+        for chunk in response['Body'].iter_chunks():
+            assert chunk.decode() == data[0:len(chunk)]
+            data = data[len(chunk):]
+
+    # request PartNumber out of range
+    e = assert_raises(ClientError, client.get_object, Bucket=bucket_name, Key=key, PartNumber=5)
+    status, error_code = _get_status_and_error_code(e.response)
+    assert status == 400
+    assert error_code == 'InvalidPart'
+
 @pytest.mark.fails_on_dbstore
 def test_non_multipart_get_part():
     bucket_name = get_new_bucket()