diff --git a/tests/test-sources/plugins/by-name/rust-tools/default.nix b/tests/test-sources/plugins/by-name/rust-tools/default.nix
index bd1780f7..8b484ea3 100644
--- a/tests/test-sources/plugins/by-name/rust-tools/default.nix
+++ b/tests/test-sources/plugins/by-name/rust-tools/default.nix
@@ -71,4 +71,13 @@
       };
     };
   };
+
+  rust-analyzer-options = {
+    plugins.rust-tools = {
+      enable = true;
+      server = {
+        assist.expressionFillDefault = "default";
+      };
+    };
+  };
 }