_frontend: Earlier assertion for `bst workspace open` when directory is not empty

This just raises the error to the user that the checkout directory
where they intend to create a workspace in is not empty, a little
bit earlier, without bothering to initialize the pipeline first.

2 files changed, 10 insertions, 3 deletions

diff --git a/buildstream/_frontend/app.py b/buildstream/_frontend/app.py
index 767e0cf1b..fe2c460c5 100644
--- a/buildstream/_frontend/app.py
+++ b/buildstream/_frontend/app.py
@@ -474,9 +474,6 @@ class App():
         workspace = self.project.workspaces.create_workspace(target.name, workdir)
 
         if not no_checkout:
-            if not force and os.listdir(directory):
-                raise AppError("Checkout directory is not empty: {}".format(directory))
-
             with target.timed_activity("Staging sources to {}".format(directory)):
                 target._open_workspace()
 
diff --git a/buildstream/_frontend/cli.py b/buildstream/_frontend/cli.py
index fadfaf59b..9720bc44e 100644
--- a/buildstream/_frontend/cli.py
+++ b/buildstream/_frontend/cli.py
@@ -613,6 +613,16 @@ def workspace():
 def workspace_open(app, no_checkout, force, track_, element, directory):
     """Open a workspace for manual source modification"""
 
+    if os.path.exists(directory):
+
+        if not os.path.isdir(directory):
+            click.echo("Checkout directory is not a directory: {}".format(directory), err=True)
+            sys.exit(-1)
+
+        if not (no_checkout or force) and os.listdir(directory):
+            click.echo("Checkout directory is not empty: {}".format(directory), err=True)
+            sys.exit(-1)
+
     with app.initialized((element,), rewritable=track_, track_elements=[element] if track_ else None):
         app.open_workspace(directory, no_checkout, track_, force)