python312Packages.sphinx: add breathe to passthru.tests

pkgs/development/python-modules/sphinx/default.nix

@@ -36,6 +36,9 @@
   html5lib,
   pytestCheckHook,
   pytest-xdist,
+
+  # reverse dependencies to test
+  breathe,
 }:
 
 buildPythonPackage rec {
@@ -143,6 +146,10 @@ buildPythonPackage rec {
       "test_partialfunction"
     ];
 
+  passthru.tests = {
+    inherit breathe;
+  };
+
   meta = {
     description = "Python documentation generator";
     longDescription = ''