From c3bdbd3a061e01e7a2c47e679310030ac88be599 Mon Sep 17 00:00:00 2001
From: Gary Yendell <gary.yendell@diamond.ac.uk>
Date: Tue, 18 Jun 2024 12:51:02 +0000
Subject: [PATCH] Fix GUI PVs with no attribute path

---
 src/fastcs/backends/epics/gui.py |  5 ++---
 tests/backends/epics/test_gui.py | 11 +++++++++++
 2 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 tests/backends/epics/test_gui.py

diff --git a/src/fastcs/backends/epics/gui.py b/src/fastcs/backends/epics/gui.py
index 66473f0d..a7562920 100644
--- a/src/fastcs/backends/epics/gui.py
+++ b/src/fastcs/backends/epics/gui.py
@@ -50,9 +50,8 @@ def __init__(self, mapping: Mapping, pv_prefix: str) -> None:
         self._pv_prefix = pv_prefix
 
     def _get_pv(self, attr_path: list[str], name: str):
-        attr_prefix = ":".join(attr_path)
-        pv_prefix = ":".join((self._pv_prefix, attr_prefix))
-        return f"{pv_prefix}:{name.title().replace('_', '')}"
+        attr_prefix = ":".join([self._pv_prefix] + attr_path)
+        return f"{attr_prefix}:{name.title().replace('_', '')}"
 
     @staticmethod
     def _get_read_widget(datatype: DataType) -> ReadWidget:
diff --git a/tests/backends/epics/test_gui.py b/tests/backends/epics/test_gui.py
new file mode 100644
index 00000000..53ab7c01
--- /dev/null
+++ b/tests/backends/epics/test_gui.py
@@ -0,0 +1,11 @@
+from fastcs.backends.epics.gui import EpicsGUI
+from fastcs.controller import Controller
+from fastcs.mapping import Mapping
+
+
+def test_get_pv():
+    gui = EpicsGUI(Mapping(Controller()), "DEVICE")
+
+    assert gui._get_pv([], "A") == "DEVICE:A"
+    assert gui._get_pv(["B"], "C") == "DEVICE:B:C"
+    assert gui._get_pv(["D", "E"], "F") == "DEVICE:D:E:F"