Support optional chaining in .at() transform (#13528)

tests/unit/syntax-transform.js

@@ -0,0 +1,51 @@
+/* eslint-disable quotes -- `toMatchInlineSnapshot` uses template literal */
+import url from "node:url";
+import path from "node:path";
+import transformCode from "../../scripts/build/transform/index.js";
+
+const file = url.fileURLToPath(
+  new URL("../../src/__dummy.js", import.meta.url)
+);
+const shimsDirectory = url.fileURLToPath(
+  new URL("../../scripts/build/shims", import.meta.url)
+);
+const transform = (code) =>
+  transformCode(code, file).replaceAll(
+    JSON.stringify(shimsDirectory + path.sep).slice(1, -1),
+    "<SHIMS>/"
+  );
+
+test("Object.hasOwn", () => {
+  expect(transform("Object.hasOwn(foo, bar)")).toMatchInlineSnapshot(
+    `"Object.prototype.hasOwnProperty.call(foo, bar);"`
+  );
+});
+
+test(".at", () => {
+  expect(transform("foo.at(-1)")).toMatchInlineSnapshot(`
+    "import __at from "<SHIMS>/at.js";
+
+    __at(false, foo, -1);"
+  `);
+
+  expect(transform("foo?.at(-1)")).toMatchInlineSnapshot(`
+    "import __at from "<SHIMS>/at.js";
+
+    __at(true, foo, -1);"
+  `);
+
+  expect(transform("foo?.bar.baz.at(-1)")).toMatchInlineSnapshot(`
+    "import __at from "<SHIMS>/at.js";
+
+    __at(true, foo?.bar.baz, -1);"
+  `);
+
+  expect(transform("foo.at(-1)?.bar")).toMatchInlineSnapshot(`
+    "import __at from "<SHIMS>/at.js";
+
+    __at(false, foo, -1)?.bar;"
+  `);
+
+  // Don't support optional call
+  expect(transform("foo.at?.(-1)")).toMatchInlineSnapshot(`"foo.at?.(-1)"`);
+});