Add some tests for bundlefile and improve the error messages for LoadFile

Signed-off-by: Daniel Nephin <dnephin@docker.com>
Upstream-commit: c0ea589c1b27f8b68e84cfe6692a7639da52ce6d
Component: engine

components/engine/api/client/stack/opts.go

@@ -31,7 +31,12 @@ func loadBundlefile(stderr io.Writer, namespace string, path string) (*bundlefil
 	}
 
 	fmt.Fprintf(stderr, "Loading bundle from %s\n", path)
-	bundle, err := bundlefile.LoadFile(path)
+	reader, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	bundle, err := bundlefile.LoadFile(reader)
 	if err != nil {
 		return nil, fmt.Errorf("Error reading %s: %v\n", path, err)
 	}