[Folding ranges]: traverse Pstr_extension

ocaml-lsp-server/src/folding_range.ml

@@ -55,6 +55,12 @@ let fold_over_parsetree (parsetree : Mreader.parsetree) =
       Ast_iterator.default_iterator.class_field self class_field
     in
 
+    let class_type_declaration (self : Ast_iterator.iterator)
+        (class_type_decl : Parsetree.class_type_declaration) =
+      Range.of_loc class_type_decl.pci_loc |> push;
+      Ast_iterator.default_iterator.class_type_declaration self class_type_decl
+    in
+
     let value_binding (self : Ast_iterator.iterator)
         (value_binding : Parsetree.value_binding) =
       let range = Range.of_loc value_binding.pvb_loc in
@@ -185,21 +191,22 @@ let fold_over_parsetree (parsetree : Mreader.parsetree) =
       | Pstr_module _
       | Pstr_eval _
       | Pstr_recmodule _
+      | Pstr_extension _
+      | Pstr_class_type _
       | Pstr_open _ ->
         Ast_iterator.default_iterator.structure_item self structure_item
       | Pstr_primitive _
       | Pstr_typext _
       | Pstr_exception _
-      | Pstr_class_type _
       | Pstr_include _
-      | Pstr_attribute _
-      | Pstr_extension _ -> ()
+      | Pstr_attribute _ -> ()
     in
 
     { Ast_iterator.default_iterator with
       case
     ; class_declaration
     ; class_field
+    ; class_type_declaration
     ; expr
     ; extension
     ; module_binding

ocaml-lsp-server/test/e2e/__tests__/textDocument-foldingRange.test.ts

@@ -670,4 +670,58 @@ describe("textDocument/foldingRange", () => {
       ]
     `);
   });
+
+  it("traverses Pstr_extension structure item", async () => {
+    await openDocument(outdent`
+    let%expect_test "test from jsonrpc_test.ml" =
+      let a =
+        let b = 5 in
+        6 + 5
+      in
+      Stdlib.print_endline (string_of_int 5)
+    `);
+
+    let result = await foldingRange();
+    expect(result).toMatchInlineSnapshot(`
+      Array [
+        Object {
+          "endCharacter": 40,
+          "endLine": 5,
+          "kind": "region",
+          "startCharacter": 0,
+          "startLine": 0,
+        },
+        Object {
+          "endCharacter": 9,
+          "endLine": 3,
+          "kind": "region",
+          "startCharacter": 2,
+          "startLine": 1,
+        },
+      ]
+    `);
+  });
+
+  it("returns folding ranges for class_type", async () => {
+    await openDocument(outdent`
+    class type foo_t =
+    object
+      inherit castable
+      method foo: string
+    end;;
+`);
+
+    let result = await foldingRange();
+    expect(result).toMatchInlineSnapshot(`
+      Array [
+        Object {
+          "endCharacter": 3,
+          "endLine": 4,
+          "kind": "region",
+          "startCharacter": 0,
+          "startLine": 0,
+        },
+      ]
+    `);
+  });
 });