From b529f57b77df5ee4dfdd48dbf8c1c8e6b10d407b Mon Sep 17 00:00:00 2001
From: RobertoRoos <robert.soor@gmail.com>
Date: Thu, 12 Mar 2026 10:48:07 +0100
Subject: [PATCH] Fixed issue when patching projects without sources at all

---
 src/tctools/patch_plc/patch_plc_class.py      | 12 ++++
 .../MyPlc/MyPlc_empty.plcproj                 | 56 +++++++++++++++++++
 tests/test_patch_plc.py                       | 11 ++++
 3 files changed, 79 insertions(+)
 create mode 100644 tests/plc_code/TwinCAT Project1/MyPlc/MyPlc_empty.plcproj

diff --git a/src/tctools/patch_plc/patch_plc_class.py b/src/tctools/patch_plc/patch_plc_class.py
index 57029de..7883483 100644
--- a/src/tctools/patch_plc/patch_plc_class.py
+++ b/src/tctools/patch_plc/patch_plc_class.py
@@ -373,6 +373,18 @@ def get_project_sources(self, tree) -> FileItems:
                 # In the XML there are always backslashes, force to native type
                 ref_set.add(path)
 
+        if self._element_files is None:  # Group doesn't yet exist, create it:
+            # It must be the first of the <ItemGroup> set
+            element_neighbour: Element = tree.find(
+                "PropertyGroup", namespaces={"": "*"}
+            )
+            self._element_files = etree.XML("<ItemGroup></ItemGroup>")
+            element_neighbour.addnext(self._element_files)
+
+        if self._element_folders is None:
+            self._element_folders = etree.XML("<ItemGroup></ItemGroup>")
+            self._element_files.addnext(self._element_folders)
+
         return sources
 
     def sources_to_remove(
diff --git a/tests/plc_code/TwinCAT Project1/MyPlc/MyPlc_empty.plcproj b/tests/plc_code/TwinCAT Project1/MyPlc/MyPlc_empty.plcproj
new file mode 100644
index 0000000..f56440e
--- /dev/null
+++ b/tests/plc_code/TwinCAT Project1/MyPlc/MyPlc_empty.plcproj	
@@ -0,0 +1,56 @@
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <FileVersion>1.0.0.0</FileVersion>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{3863e7e1-422f-4d5c-92f7-9f7ce21f2ff0}</ProjectGuid>
+    <SubObjectsSortedByName>True</SubObjectsSortedByName>
+    <DownloadApplicationInfo>true</DownloadApplicationInfo>
+    <WriteProductVersion>true</WriteProductVersion>
+    <GenerateTpy>false</GenerateTpy>
+    <Name>MyPlc</Name>
+    <ProgramVersion>3.1.4023.0</ProgramVersion>
+    <Application>{9b80525c-51bc-47f5-868f-9f61efadf857}</Application>
+    <TypeSystem>{8c1ac7e2-784c-4117-8c69-6df5131a9b7a}</TypeSystem>
+    <Implicit_Task_Info>{4cbef591-f0aa-4f71-8e8c-8748ed72f381}</Implicit_Task_Info>
+    <Implicit_KindOfTask>{bc222fda-9a00-499c-8fe1-56590e05c741}</Implicit_KindOfTask>
+    <Implicit_Jitter_Distribution>{85a038e2-e5b4-4af4-916e-a04812cc85b0}</Implicit_Jitter_Distribution>
+    <LibraryReferences>{387c9843-650a-4728-bc5d-67105fea5b12}</LibraryReferences>
+  </PropertyGroup>
+  <ItemGroup>
+    <PlaceholderReference Include="Tc2_Standard">
+      <DefaultResolution>Tc2_Standard, * (Beckhoff Automation GmbH)</DefaultResolution>
+      <Namespace>Tc2_Standard</Namespace>
+    </PlaceholderReference>
+    <PlaceholderReference Include="Tc2_System">
+      <DefaultResolution>Tc2_System, * (Beckhoff Automation GmbH)</DefaultResolution>
+      <Namespace>Tc2_System</Namespace>
+    </PlaceholderReference>
+    <PlaceholderReference Include="Tc3_Module">
+      <DefaultResolution>Tc3_Module, * (Beckhoff Automation GmbH)</DefaultResolution>
+      <Namespace>Tc3_Module</Namespace>
+    </PlaceholderReference>
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="MyPlc.tmc">
+      <SubType>Content</SubType>
+    </None>
+  </ItemGroup>
+  <ProjectExtensions>
+    <PlcProjectOptions>
+      <XmlArchive>
+        <Data>
+          <o xml:space="preserve" t="OptionKey">
+      <v n="Name">"&lt;ProjectRoot&gt;"</v>
+      <d n="SubKeys" t="Hashtable" />
+      <d n="Values" t="Hashtable" />
+    </o>
+        </Data>
+        <TypeList>
+          <Type n="Hashtable">System.Collections.Hashtable</Type>
+          <Type n="OptionKey">{54dd0eac-a6d8-46f2-8c27-2f43c7e49861}</Type>
+          <Type n="String">System.String</Type>
+        </TypeList>
+      </XmlArchive>
+    </PlcProjectOptions>
+  </ProjectExtensions>
+</Project>
\ No newline at end of file
diff --git a/tests/test_patch_plc.py b/tests/test_patch_plc.py
index 1dbec9b..851002e 100644
--- a/tests/test_patch_plc.py
+++ b/tests/test_patch_plc.py
@@ -251,3 +251,14 @@ def test_reset_duplicate(plc_dir, project, caplog):
     assert "Refusing to add" in msg and "MAIN.TcPOU" in msg
 
     assert project.read_text() == content_before  # The project should not be changed
+
+
+def test_reset_empty_project(plc_dir, caplog):
+    project = plc_dir / "MyPlc_empty.plcproj"  # Project with 0 sources
+
+    code = PatchPlc(str(project), "reset", str(plc_dir), "-r").run()
+    assert code == 0
+
+    content_after = project.read_text()
+    assert 'Include="POUs\\untracked_source\\F_UntrackedFunc.TcPOU"' in content_after
+    assert 'Include="POUs\\untracked_source"' in content_after