Easy way to generate mocks

[levibostian]

At this time, I am generating mocks manually in my code. The follow a very simple process:

interface Foo {
  bar(): string
}

class FooMock implements Foo {
  public barMock = jest.fn()

  bar: barMock
}

The problem is maintaining them. They are simply annoying to write which gets me to be lazy and not want to write them.

If there was a way to generate them automatically, that would be great. How do we do that?

• Decorators Will not work because it does not work on interfaces and it only passes the constructor of class when used on a class. No way to traverse an interface.
• Babel - I would prefer not to need to do this because I don't want my project to use babel. But if there was a way for babel to traverse my code and run my plugin and that's it, then maybe.
• ts-morph - possibly. It seems to be a nice project but I don't like relying on projects that are "still in development"
• Create a typescript transformer - these are the official way to create plugins for the typescript compiler.

FYI: handy ast viewer

[levibostian]

Here is a project that seems to do this: https://github.com/marchaos/jest-mock-extended

However, it has had a history of not being maintained and for some reason, it overrides the jest mock matcher API with Jasmine's. I am thinking of forking it and editing parts of it to be smaller and use the original jest matcher api.

See this issue for discussion around this.