Cypress: Type 'Promise<any>' is not assignable to type 'CanReturnChainable' in Cypress

[stevenvachon]

Current behavior:

Having updated from Cypress 4.8, TypeScript will now not compile my support code. #435 was not insightful.

Desired behavior:

Compile my TypeScript. Either I'm doing something wrong or there is a bug.

Test code to reproduce

Cypress.Commands.overwrite(command, (originalFn, ...args) => {
  const origVal = originalFn(...args);
  return new Promise(resolve => {
    setTimeout(() => resolve(origVal), 1000);
  });
});

It fails similarly with Cypress.Promise as well. I'd like to avoid cy.wrap() unless necessary.

Versions

Cypress 4.9.0
macOS 10.15.5
Chrome 83

[jennifer-shehane]

@stevenvachon Hey, can you provide some more info?

• You're adding this code to a support/index.ts file?
• How are you running your tests? (cypress open, cypress run)?
• Do you have any preprocessors in your plugins?
• Do you have a tsconfig file defind?
• What is the error you are seeing?

I can't recreate this just adding this code to a support/index.ts file as you've described.

[0x80]

@jennifer-shehane I'm seeing similar behavior.

• Yes, it's code added to support/index.ts
• It's the compiler that complains. Weirdly enough the tests still run.
• No preprocessor in plugins
• Tsconfig file below

Cypress.Commands.add(
  "createReview",
  (payload: Partial<CreateReviewPayload>) => {
    const review = cleanObject<CreateReviewPayload>({
      title: payload.title || `[cy-test]`,
      description: "This is a review created for test purposes",
      tagIds: [],
      industryId: "__no_industry",
      type: "self-review",
      accountId: testAccountId,
      ...payload,
    });

    return functions
      .httpsCallable("createReview")(review)
      .then((result) => {
        const reviewId = result.data.reviewId as string;
        return firestore
          .collection("reviews")
          .doc(reviewId)
          .get()
          .then((snap) => ({
            id: reviewId,
            data: snap.data() as Review,
          }));
      });
  },
);

Error:

Argument of type '(payload: Partial<CreateReviewPayload>) => Promise<{ id: string; data: Review; }>' is not assignable to parameter of type '(...args: any[]) => CanReturnChainable'.
  Type 'Promise<{ id: string; data: Review; }>' is not assignable to type 'CanReturnChainable'.
    Type 'Promise<{ id: string; data: Review; }>' is missing the following properties from type 'Chainable<any>': and, as, blur, check, and 89 more.ts(2345)

{
  "compilerOptions": {
    "esModuleInterop": true,
    "jsx": "preserve",
    "lib": ["dom", "esnext"],
    "types": ["cypress", "node"],
    "module": "esnext",
    "moduleResolution": "node",
    "noEmit": true,
    "noUnusedLocals": false,
    "noUnusedParameters": false,
    "preserveConstEnums": true,
    "removeComments": false,
    "skipLibCheck": true,
    "checkJs": false,
    "sourceMap": true,
    "strict": true,
    "target": "es2018",
    "allowJs": false,
    "forceConsistentCasingInFileNames": true,
    "resolveJsonModule": true,
    "baseUrl": ".",
    "paths": {
      "/*": ["./src/*"]
    }
  }
}

For me this issue also started when upgrading from 4.8 to 4.9

[araujobarret]

@jennifer-shehane @0x80 I faced the same situation here, but with MailSlurp service:
// command.ts

import { MailSlurp } from 'mailslurp-client';

const getMailSlurpInstance = (apiKey: string) => {
  return new MailSlurp({ apiKey });
};

Cypress.Commands.add('createInbox', (apiKey: string) => {
  return getMailSlurpInstance(apiKey).createInbox();
});

This expected type from the command CanReturnChainable it is more a blocker than a helper in my case, just downgraded to version 4.8.0 as a workaround from now.

[lansana]

This issue also appears in 5.0.0

[sainthkh]

Confirmed. Trying to find the fix.

[0x80]

I worked around it by returning my promise prefixed with cy.window().then(() => myAsyncFunction()). I'm not using the window result but the return value will therefor get the chainable type.

[cypress-bot[bot]]

The code for this is done in cypress-io/cypress#8501, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[cypress-bot[bot]]

Released in 5.2.0.

This comment thread has been locked. If you are still experiencing this issue after upgrading to
Cypress v5.2.0, please open a new issue.