is there a way to type compare methods of 2 typescript modules?-CodePudding

examples:

api.ts

export const getStuffs = async (term:string): Promise<Stuff[]> => {
   const stuffs = await getStuffsFromDB(term);
   return stuffs;
}

mock_api.ts

export const getStuffs = async (term:string): Promise<Stuff[]> => {
   const stuffs = [
     { ... hardcoded stuff }
   ];
   return stuffs;
}

is there a way to add in a CI/CD test to compare that the two provided example module above are equal in type input/output: (term:string):Promise<stuff[]> ?

The objective is to automatically remind devs to always replicate the exported methods in api.ts to be mocked in mock_api.ts

CodePudding user response：

Using the two generic helper types IfEquals and BeTrue, we can check at compile time if two types are equal.

type IfEquals<T, U> =
  (<G>() => G extends T ? 1 : 2) extends
  (<G>() => G extends U ? 1 : 2) ? true : false;

type BeTrue<T extends true> = T

Import both functions into a single file but be sure two give one of them an alias to avoid the naming collision.

You can now check the two function types for equality.

declare let res: BeTrue<IfEquals<typeof getStuffs, typeof getStuffs2>>

This line will emit a compile time error if the types are not equal.

Playground

CodePudding user response：

The objective is to automatically remind devs to always replicate the exported methods in api.ts to be mocked in mock_api.ts

You don't really need CI/CD to check this for you, instead you could simply create a interface that defines the methods you need:

interface ApiMethods {
    getStuffs: (term: string) => Promise<any[]>
}

Then create an object in each of your files that implement this interface:

const apiMethods: ApiMethods = {
    getStuffs: async () => {
        return new Promise((resolve, reject) => {resolve([])});
    }
}

const mockMethods: ApiMethods = {
    getStuffs: async () => {
        return new Promise((resolve, reject) => {resolve([])});
    }
}

Adding a new method/property to ApiMethods will now force you to implement those in apiMethods and mockMethods.