Combine factories with optional field

[jagers]

Hello,

I'm trying to combine factories for an interface that has an optional field and I'm running into a typescript error.
Using the following example:

const softDelete = Sync.makeFactory({
    isDeleted: false,
})
interface Post {
    content?: string
    isDeleted: boolean
}
const postFactory: Sync.Factory<Post> = Sync.makeFactory({
    content: 'lorem ipsum',
}).combine(softDelete)

TS compilation results in:

TS2322: Type 'Factory<{ content: string; } & { isDeleted: boolean; }, "isDeleted" | "content">' is not assignable to type 'Factory<Post, keyof Post>'.
  The types of 'builder.isDeleted' are incompatible between these types.
    Type 'boolean | Generator<boolean> | Derived<{ content: string; } & { isDeleted: boolean; }, boolean>' is not assignable to type 'boolean | Generator<boolean> | Derived<Post, boolean>'.
      Type 'Derived<{ content: string; } & { isDeleted: boolean; }, boolean>' is not assignable to type 'boolean | Generator<boolean> | Derived<Post, boolean>'.
        Type 'Derived<{ content: string; } & { isDeleted: boolean; }, boolean>' is not assignable to type 'Derived<Post, boolean>'.
          Type 'Post' is not assignable to type '{ content: string; } & { isDeleted: boolean; }'.

Am I missing something or is this a bug?

[AntwanSherif]

I have same problem. Did you manage to solve it?

[jagers]

Unfortunately, I did not find a good solution. I ended up coming up with a hack that got things sort of working but it's not ideal. Essentially I use the Typescript Required<> utility when defining the factory:

const postFactory: Sync.Factory<Required<Post>> = Sync.makeFactory({
    content: 'lorem ipsum',
}).combine(softDelete)

This gets rid of the TS error but the downside is that the factory has to define a value for fields that should technically be allowed to be undefined

[thenbe]

This issue affects nullable properties as well.