fstests: add FsRootCollapse test - #3164

backend/onedrive/onedrive.go

@@ -385,9 +385,19 @@ func (f *Fs) readMetaDataForPath(path string) (info *api.Item, resp *http.Respon
 	var dirCacheFoundRoot bool
 	var rootNormalizedID string
 	if f.dirCache != nil {
-		var ok bool
-		if rootNormalizedID, ok = f.dirCache.Get(""); ok {
-			dirCacheFoundRoot = true
+		var dirCacheRootIDExists bool
+		rootNormalizedID, dirCacheRootIDExists = f.dirCache.Get("")
+		if f.root == "" {
+			// if f.root == "", it means f.root is the absolute root of the drive
+			// and its ID should have been found in NewFs
+			dirCacheFoundRoot = dirCacheRootIDExists
+		} else if _, err := f.dirCache.RootParentID(); err == nil {
+			// if root is in a folder, it must have a parent folder, and
+			// if dirCache has found root in NewFs, the parent folder's ID
+			// should be present.
+			// This RootParentID() check is a fix for #3164 which describes
+			// a possible case where the root is not found.
+			dirCacheFoundRoot = dirCacheRootIDExists
 		}
 	}
 

fstest/fstests/fstests.go

@@ -1583,6 +1583,27 @@ func Run(t *testing.T, opt *Opt) {
 
 		})
 
+		// TestFsRootCollapse tests if the root of an fs "collapses" to the
+		// absolute root. It creates a new fs of the same backend type with its
+		// root set to a *non-existent* folder, and attempts to read the info of
+		// an object in that folder, whose name is taken from a directory that
+		// exists in the absolute root.
+		// This test is added after
+		// https://github.com/ncw/rclone/issues/3164.
+		t.Run("FsRootCollapse", func(t *testing.T) {
+			deepRemoteName := subRemoteName + "/deeper/nonexisting/directory"
+			deepRemote, err := fs.NewFs(deepRemoteName)
+			require.NoError(t, err)
+
+			colonIndex := strings.IndexRune(deepRemoteName, ':')
+			firstSlashIndex := strings.IndexRune(deepRemoteName, '/')
+			firstDir := deepRemoteName[colonIndex+1 : firstSlashIndex]
+			_, err = deepRemote.NewObject(firstDir)
+			require.Equal(t, fs.ErrorObjectNotFound, err)
+			// If err is not fs.ErrorObjectNotFound, it means the backend is
+			// somehow confused about root and absolute root.
+		})
+
 		// Purge the folder
 		err = operations.Purge(remote, "")
 		require.NoError(t, err)