message: Add tests for cases where  should not show refactoring
diff: +import * as t from "../../ast";
  import { InMemoryEditor } from "../../editor/adapters/in-memory-editor";
  import { AbsolutePath, Code, ErrorReason } from "../../editor/editor";
  +import { Selection } from "../../editor/selection";
  import { testEach } from "../../tests-helpers";
  -import { changeSignature } from "./change-signature";
  +import { changeSignature, createVisitor } from "./change-signature";
  type TestSample = {
  code: Code;
  @@ -541,6 +543,45 @@ describe("Change Signature", () => {
  const extracted = await editor.codeOf(setup.path);
  expect(extracted).toBe(expected.currentFile);
  });
  +
  + testEach<{ code: Code; selection?: Selection }>(
  + "should not show refactoring",
  + [
  + {
  + description: "on an arrow function without parameters",
  + code: `const add = () => {
  + return 0;
  + };`,
  + selection: Selection.cursorAt(0, 13)
  + },
  + {
  + description: "on an function without parameters",
  + code: `function add() {
  + return 0;
  + }`,
  + selection: Selection.cursorAt(0, 9)
  + },
  + {
  + description: "on an class method without parameters",
  + code: `class Math {
  + add() {
  + return 0;
  + }
  + }`,
  + selection: Selection.cursorAt(1, 23)
  + }
  + ],
  + ({ code, selection = Selection.cursorAt(0, 13) }) => {
  + const ast = t.parse(code);
  + let canConvert = false;
  + t.traverseAST(
  + ast,
  + createVisitor(selection, () => (canConvert = true))
  + );
  +
  + expect(canConvert).toBeFalsy();
  + }
  + );
  });
  function validateOutput(
  