TypeScript: Better Generic Support for td.object()

[sgtoj]

Given the following...

import * as td from "testdouble";

class FooBar {
  private _date: Date;
  constructor() {
    this._date = new Date();
  }
  public dateString() {
    return this._date.toString();
  }
}

let fooBarFake = td.object<FooBar>("FooBar" as any);

The above code will set fooBarFake to FooBar object as expected. TypeScript and fooBarFake behaves as I expect too. However, without as any, TypeScript will throw the following error...

'"FooBar"' is not assignable to parameter of 'FooBar'

Take notice of the quote marks. Without the generic parameter (<FooBar> ), TypeScript fooBarFake thinks it of String type.

I believe the parameter should not need to be cast as any type for the generic parameter to be accepted.

import * as td from "testdouble";

// define FooBar class here

let fooBarFake = td.object<FooBar>("FooBar");

As side note, I generally set TypeScript's noImplicitAny setting is to true.

[searls]

I have no idea how to TypeScript. Would you send a PR?

[sgtoj]

I will look in to the source later (tonight afterwork?). I don't think the solution will be too difficult. Believe there only needs to be a small change to the way Proxy objects are created.

[searls]

Thanks! I met a few very nice people at NG Conf who offered to help make the typescript story for testdouble really shine, so we can find more help if needed

[searls]

Related, when you dig in there is a test:typescript script but I can't tell that it actually does anything. Any fix to that (or a new test that actually fails when broken) would be awesome

[sgtoj]

I have determined the caused TypeScript error is due to lodash's .tap() function -- docs. More specifically, I believe it's due to the function's interface definition defined in @types/lodash. Furthermore, it is working as designed: the explicit generic type parameter is suppose to match the first parameter's type.

I believe solution is creating a TypeScript definition for testdouble.js. Probably what the guys at the NG Conf were thinking too.

[searls]

Someone else has done this in an index.d.ts file in this repo already right?

…

On May 3, 2017, at 8:34 PM, Brian ***@***.***> wrote: I have determined the caused TypeScript error is due to lodash's .tap() function -- docs. More specifically, I believe it's due to the function's interface definition defined in @types/lodash. Furthermore, it is working as designed: the explicit generic type parameter is suppose to match the first parameter's type. I believe solution is creating a TypeScript definition for testdouble.js. Probably what the guys at the NG Conf were thinking too. ― You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[sgtoj]

You're right! Thanks! Overloading the object() function works too. I will push a PR soon.

[sgtoj]

Pull #237 submitted. As for your question about test:typescript, it does what it can because there is no real way to test *.d.ts. So that npm script runs the TS compiler against a test.ts script without generating a compiled script. If there were any type errors, the tsc throw them.