Use a FileStorage object instead of a tuple when testing direct modulemd submissions

It seems that there is a bug with the Flask test client when submitting a tuple of
file path and content, that incorrectly sets the filename to be the first line of
the file contents instead of the actual filename. We should eventually investigate
this and report a bug or provide a patch.

tests/test_build/test_build.py

@@ -39,6 +39,7 @@ from module_build_service import db, models, conf, build_logs
 from tests import get_vcr_path
 
 from mock import patch, PropertyMock, Mock
+from werkzeug.datastructures import FileStorage
 import kobo
 
 from tests import app, test_reuse_component_init_data, clean_database
@@ -437,16 +438,15 @@ class TestBuild:
     @patch('module_build_service.scm.SCM')
     def test_submit_build_from_yaml_allowed(self, mocked_scm, mocked_get_user, conf_system, dbg):
         FakeSCM(mocked_scm, "testmodule", "testmodule.yaml")
-
         testmodule = os.path.join(base_dir, 'staged_data', 'testmodule.yaml')
-        with open(testmodule) as f:
-            yaml = f.read()
 
         with patch.object(module_build_service.config.Config, 'yaml_submit_allowed',
                           new_callable=PropertyMock, return_value=True):
-            rv = self.client.post('/module-build-service/1/module-builds/',
-                                  content_type='multipart/form-data',
-                                  data={'yaml': (testmodule, yaml)})
+            with open(testmodule, 'rb') as f:
+                yaml_file = FileStorage(f)
+                rv = self.client.post('/module-build-service/1/module-builds/',
+                                      content_type='multipart/form-data',
+                                      data={'yaml': yaml_file})
             data = json.loads(rv.data)
             assert data['id'] == 1