WIP: Fix cache miss when calling WorkspaceProjectCache.get() on different...

WIP: Fix cache miss when calling WorkspaceProjectCache.get() on different directories in the same workspace

buildstream/_workspaces.py

@@ -165,24 +165,29 @@ class WorkspaceProjectCache():
 
     # get()
     #
-    # Returns a WorkspaceProject for a given directory, loading one from disk if present
-    # and caching it.
+    # Returns a WorkspaceProject for a given directory, retrieving from the cache if
+    # present, and searching the filesystem for the file and loading it if not.
     #
     # Args:
     #    directory (str): The directory to search for a WorkspaceProject.
     #
     # Returns:
     #    (WorkspaceProject): The WorkspaceProject that was found for that directory.
+    #    or      (NoneType): None, if no WorkspaceProject can be found.
     #
     def get(self, directory):
-        # NOTE: Later, this will load any WorkspaceProject found from directory
         try:
             workspace_project = self._projects[directory]
         except KeyError:
-            workspace_project = WorkspaceProject.load(directory)
-            if not workspace_project:
-                workspace_project = WorkspaceProject(directory)
-            self._projects[directory] = workspace_project
+            found_dir = WorkspaceProject.search_for_dir(directory)
+            if found_dir:
+                try:
+                    workspace_project = self._projects[found_dir]
+                except KeyError:
+                    workspace_project = WorkspaceProject.load(found_dir)
+                    self._projects[found_dir] = workspace_project
+            else:
+                workspace_project = None
 
         return workspace_project
 
@@ -201,6 +206,9 @@ class WorkspaceProjectCache():
     #
     def add(self, directory, project_path='', element_name=''):
         workspace_project = self.get(directory)
+        if not workspace_project:
+            workspace_project = WorkspaceProject(directory)
+            self._projects[directory] = workspace_project
         if project_path:
             workspace_project._add_project(project_path, element_name)
         return workspace_project
@@ -223,6 +231,9 @@ class WorkspaceProjectCache():
         # NOTE: project_path and element_name will only be used when I implement
         #       multiple owners of a workspace
         workspace_project = self.get(directory)
+        if not workspace_project:
+            raise LoadError(LoadErrorReason.MISSING_FILE,
+                            "Failed to find a {} file to remove".format(WORKSPACE_PROJECT_FILE))
         path = workspace_project._get_filename()
         try:
             os.unlink(path)