diff --git a/tests/lean/run/Reparen.lean b/tests/lean/run/Reparen.lean
new file mode 100644
index 0000000000..5f0dddf52b
--- /dev/null
+++ b/tests/lean/run/Reparen.lean
@@ -0,0 +1,49 @@
+/-! Reprint file after removing all parentheses and then passing it through the parenthesizer -/
+import Init.Lean.PrettyPrinter.Parenthesizer
+
+open Lean
+open Lean.Elab
+open Lean.Elab.Term
+open Lean.Format
+
+def Substring.beq (ss1 ss2 : Substring) : Bool :=
+ss1.toString == ss2.toString
+
+instance : HasBeq Substring := ⟨Substring.beq⟩
+
+partial def Lean.Syntax.structEq : Syntax → Syntax → Bool
+| Syntax.missing, Syntax.missing => true
+| Syntax.node k args, Syntax.node k' args' => k == k' && args.isEqv args' Lean.Syntax.structEq
+| Syntax.atom _ val, Syntax.atom _ val' => val == val'
+| Syntax.ident _ rawVal val preresolved, Syntax.ident _ rawVal' val' preresolved' => rawVal == rawVal' && val == val' && preresolved == preresolved'
+| _, _ => false
+
+instance : HasBeq Lean.Syntax := ⟨Lean.Syntax.structEq⟩
+
+def unparenAux (parens body : Syntax) : Syntax :=
+match parens.getHeadInfo, body.getHeadInfo, body.getTailInfo, parens.getTailInfo with
+| some bi', some bi, some ti, some ti' => (body.setHeadInfo { bi with leading := bi'.leading }).setTailInfo { ti with trailing := ti'.trailing }
+| _, _, _, _ => body
+
+partial def unparen : Syntax → Syntax
+| stx => match_syntax stx with
+  | `(($stx')) => unparenAux stx $ unparen stx'
+  | `(level|($stx')) => unparenAux stx $ unparen stx'
+  | _ => stx.modifyArgs $ Array.map unparen
+
+def main (args : List String) : IO Unit := do
+initSearchPath none;
+env ← importModules [{module := `Init.Lean.Parser}];
+stx ← Lean.Parser.parseFile env args.head!;
+(stx', env) ← IO.runMeta (do
+    let cmds := stx.getArgs.extract 1 stx.getArgs.size;
+    args ← cmds.mapM $ PrettyPrinter.parenthesizeCommand ∘ unparen;
+    pure $ stx.setArgs (#[stx.getArgs.get! 0] ++ args)
+  )
+  -- change to `true` for trace output
+  env { opts := KVMap.insert {} `trace.PrettyPrinter.parenthesize false };
+some s ← pure stx'.reprint | throw $ IO.userError "reprint failed";
+true ← Parser.testModuleParser env s | throw $ IO.userError "reparse failed";
+IO.print s
+
+#eval main ["../../../src/Init/Core.lean"]