Update tests to include dry run, and do a general related refactor of…

… test_filesystem_transfer for clarity.

tests/test_utils.py

@@ -428,42 +428,64 @@ def get_top_level_folder_path(
 def handle_upload_or_download(
     project,
     upload_or_download,
-    specific_top_level_folder=False,
-    transfer_entire_project=False,
+    transfer_method,
+    top_level_folder=None,
     swap_last_folder_only=False,
 ):
     """
     To keep things consistent and avoid the pain of writing
     files over SSH, to test download just swap the central
     and local server (so things are still transferred from
     local machine to central, but using the download function).
+
+    Also returns the transfer method, if 'transfer_method="top_level_folder"`
+    then the `top_level_folder` is used to determine the method,
+    otherwise it is not used.
     """
     if upload_or_download == "download":
         central_path = swap_local_and_central_paths(
             project, swap_last_folder_only
         )
+    else:
+        central_path = project.cfg["central_path"]
+
+    transfer_function = get_transfer_func(
+        project, upload_or_download, transfer_method, top_level_folder
+    )
+
+    return transfer_function, central_path
+
 
-        if transfer_entire_project:
+def get_transfer_func(
+    project, upload_or_download, transfer_method, top_level_folder=None
+):
+    """"""
+    if transfer_method == "top_level_folder":
+        assert top_level_folder is not None, "must pass top-level-folder"
+    assert top_level_folder in [None, "rawdata", "derivatives"]
+
+    if upload_or_download == "download":
+        if transfer_method == "entire_project":
             transfer_function = project.download_entire_project
-        elif specific_top_level_folder == "rawdata":
-            transfer_function = project.download_rawdata
-        elif specific_top_level_folder == "derivatives":
-            transfer_function = project.download_derivatives
+        elif transfer_method == "top_level_folder":
+            if top_level_folder == "rawdata":
+                transfer_function = project.download_rawdata
+            else:
+                transfer_function = project.download_derivatives
         else:
             transfer_function = project.download_custom
     else:
-        central_path = project.cfg["central_path"]
-
-        if transfer_entire_project:
+        if transfer_method == "entire_project":
             transfer_function = project.upload_entire_project
-        elif specific_top_level_folder == "rawdata":
-            transfer_function = project.upload_rawdata
-        elif specific_top_level_folder == "derivatives":
-            transfer_function = project.upload_derivatives
+        elif transfer_method == "top_level_folder":
+            if top_level_folder == "rawdata":
+                transfer_function = project.upload_rawdata
+            else:
+                transfer_function = project.upload_derivatives
         else:
             transfer_function = project.upload_custom
 
-    return transfer_function, central_path
+    return transfer_function
 
 
 def swap_local_and_central_paths(project, swap_last_folder_only=False):