Support with Vitest TypeScript Setup

[stockbal]

Hi CAP community,

Since CDS 9.9, vitest is officially supported as a test runner, so I wanted to try it out.
As I use TypeScript in most of my projects I wanted to get vitest setup with TypeScript. For vitest this shouldn't be a problem, but the CDS server runs into some problems with the module loading.

The issue comes up when a test suite runs cds.test

import cds from "@sap/cds";

const { GET, POST, defaults } = cds.test(__dirname + "/..");
defaults.auth = { username: "alice", password: "" };

describe("AdminService OData APIs", () => {
  it("serves AdminService.Authors", async () => {
    const { data } =
      await GET`/odata/v4/admin/Authors ${{ params: { $select: "ID,name" } }}`;
    expect(data.value).to.containSubset([{ ID: 101, name: "Emily Brontë" }]);
  });
});

the cds server is correctly finding the .ts implementations for the services, but breaks during loading a local module.

import cds from "@sap/cds"; // correctly loaded

import { Authors, Books } from "#cds-models/AdminService"; // correctly loaded
import { genid } from "./utils/id"; // module cannot be found

export class AdminService extends cds.ApplicationService {
  init() {
    this.before("NEW", Authors.drafts, genid);
    this.before("NEW", Books.drafts, genid);
    this.before("CREATE", Authors, genid);
    this.before("CREATE", Books, genid);
    return super.init();
  }
}

If I run cds w - tsx is installed - the cds server starts correctly and everything works.

I created a sample repository here where the issue occurs. The latest versions of vitest, TypeScript and cds are used.

Any hints/help on this topic would be greatly appreciated

Thx and Regards,
Ludwig

[sueun-dev]

The CDS server loads your service .ts files with its own runtime loader, not through vitest's transform, so vitest only transforms the test files. Your srv/server.ts (and admin-service.ts) do the extensionless import { genid } from "./utils/id", and with no TS loader active for that load Node can't resolve ./utils/id.ts, hence Cannot find module .../srv/utils/id imported from .../srv/server.ts. cds w works because it runs under tsx, which is the active loader there.

Fix: register tsx for the vitest process too, so CDS's loads resolve .ts:

// package.json
"scripts": { "test": "NODE_OPTIONS='--import tsx' vitest" }

I reproduced it on your sample repo (cds 9, vitest 4): without the flag cds.test fails with exactly that srv/utils/id error, with --import tsx AdminService passes 2/2. On Windows wrap it with cross-env. The CDS_TYPESCRIPT=true in vitest.config isn't enough on its own since it doesn't register the loader.

[stockbal]

Thanks, this works - when running the tests via npm. To also run the tests via the official vitest - vsc extension you have to register tsx also there:

  "vitest.nodeEnv": {
    "NODE_OPTIONS": "--import=tsx"
  }