diff --git a/test/units/_internal/_ansiballz/__init__.py b/test/units/_internal/_ansiballz/__init__.py
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/test/units/_internal/_ansiballz/test_builder.py b/test/units/_internal/_ansiballz/test_builder.py
new file mode 100644
index 00000000000..e48f7e0f997
--- /dev/null
+++ b/test/units/_internal/_ansiballz/test_builder.py
@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+from ansible._internal._ansiballz._builder import ExtensionManager
+from ansible.module_utils._internal._ansiballz._extensions import _pydevd
+
+
+def test_debugger_source_mapping() -> None:
+    """Synthetic coverage for builder source mapping."""
+    debug_options = _pydevd.Options(source_mapping={
+        "ide/path.py": "controller/path.py",
+        "ide/something.py": "controller/not_match.py",
+    })
+
+    manager = ExtensionManager(debug_options)
+    manager.source_mapping.update({
+        "controller/path.py": "zip/path.py",
+        "controller/other.py": "not_match.py",
+    })
+
+    extensions = manager.get_extensions()
+
+    assert extensions['_pydevd']['source_mapping'] == {'controller/other.py': 'not_match.py', 'ide/path.py': 'zip/path.py'}