Error when running with Jest

[lalalune]

Project is building and working, here's the code: https://github.com/hwchase17/langchainjs/blob/main/langchain/agents/tools/serpapi.ts

Testing with jest: TypeError: Cannot convert undefined or null to object

Other tests work, just something with SerpApi... has this been encountered before?

[sebastianquek]

Interesting. The issue stems from ts-jest/babel-jest trying to transform serpapi's exports to CommonJS although they are already in CommonJS syntax. More specifically the domexception library:

import { test } from "@jest/globals";
import DOMException from "domexception";

test("test", async () => {
  const e1 = new DOMException("Something went wrong", "BadThingsError");
  expect(e1.name).toEqual("BadThingsError");
});

> jest

 FAIL  ./example.test.ts
  ● Test suite failed to run

    TypeError: Cannot convert undefined or null to object
        at Function.getPrototypeOf (<anonymous>)

      1 | import { test } from "@jest/globals";
    > 2 | import DOMException from "domexception";
        | ^
      3 |
      4 | test("test", async () => {
      5 |   const e1 = new DOMException("Something went wrong", "BadThingsError");

      at Object.<anonymous> (node_modules/domexception/lib/utils.js:34:39)
      at Object.<anonymous> (node_modules/domexception/lib/DOMException.js:4:15)
      at Object.<anonymous> (node_modules/domexception/webidl2js-wrapper.js:2:22)
      at Object.<anonymous> (node_modules/domexception/index.js:2:22)
      at Object.<anonymous> (example.test.ts:2:1)

One way to resolve this is to remove transformIgnorePatterns so that the default pattern is used. This excludes node_modules from getting transformed. Unless there was some reason to transform them? [EDIT: see below for a better approach]

--- a/langchain/jest.config.js
+++ b/langchain/jest.config.js
@@ -7,7 +7,5 @@ module.exports = {
     "^.+\\.(ts|tsx)$": "ts-jest",
     "^.+\\.(js)$": "babel-jest",
   },
-  transformIgnorePatterns: [
-  ],
   setupFiles: ["dotenv/config"],
 };

PS: The preset specified in jest.config.js actually isn't doing anything as the transform property is overriding it entirely.

---

EDIT: Upon diving deeper, the error is thrown here, where the prototype of the async generator function is undefined. Somehow babel is not transforming this correctly even when preset-env includes a plugin to handle this.

A better fix would be to set the babel targets to be node since you probably want langchain to run on node anyway: https://babeljs.io/docs/en/options#targetsnode

--- a/langchain/babel.config.js
+++ b/langchain/babel.config.js
@@ -1,2 +1,6 @@
 // babel.config.js
-module.exports = {presets: ['@babel/preset-env']};
+module.exports = {
+  presets: [
+    ["@babel/preset-env", { targets: { node: true } }],
+  ],
+};

[sebastianquek]

@lalalune I've updated serpapi to 1.1.1 which removes the production dependency on domexception. Let me know if you're still facing issues after the update. Will close this for now.

[lalalune]

@sebastianquek thanks, you rock!!