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coolsoftwaretyler/mst-type-tests.ts

Last active February 16, 2024 03:11
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Revisions

  1. coolsoftwaretyler revised this gist Feb 16, 2024. 1 changed file with 1 addition and 1 deletion.
    2 changes: 1 addition & 1 deletion mst-type-tests.ts
    View file
    Original file line number Diff line number Diff line change
    @@ -1,4 +1,4 @@
    // These assertions don't work, from https://github.com/mobxjs/mobx-state-tree/blob/master/__tests__/core/type-system.test.ts
    // These assertions don't work, from https://github.com/mobxjs/mobx-state-tree/blob/master/__tests__/core/type-system.test.ts. Fails with TS 4.3 and greater. https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-3.html

    test("maybe / optional type inference verification", () => {
    const T = types.model({
  2. coolsoftwaretyler revised this gist Feb 16, 2024. 1 changed file with 1 addition and 1 deletion.
    2 changes: 1 addition & 1 deletion mst-type-tests.ts
    View file
    Original file line number Diff line number Diff line change
    @@ -1,4 +1,4 @@
    // These assertions don't work
    // These assertions don't work, from https://github.com/mobxjs/mobx-state-tree/blob/master/__tests__/core/type-system.test.ts

    test("maybe / optional type inference verification", () => {
    const T = types.model({
  3. coolsoftwaretyler created this gist Feb 16, 2024.
    76 changes: 76 additions & 0 deletions mst-type-tests.ts
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,76 @@
    // These assertions don't work

    test("maybe / optional type inference verification", () => {
    const T = types.model({
    a: types.string,
    b: "test",
    c: types.maybe(types.string),
    d: types.maybeNull(types.string),
    e: types.optional(types.string, "test")
    })

    interface ITC extends SnapshotIn<typeof T> {}
    interface ITS extends SnapshotOut<typeof T> {}

    assert(
    _ as ITC, // TS error: Argument of type 'ITC' is not assignable to parameter of type '"❌ Unexpected or missing 'readonly' property"'.
    _ as {
    [$nonEmptyObject]?: any
    a: string
    b?: string
    c?: string | undefined
    d?: string | null
    e?: string
    }
    )

    assert(
    _ as ITS, // Argument of type 'ITC' is not assignable to parameter of type '"❌ Unexpected or missing 'readonly' property"'.
    _ as {
    [$nonEmptyObject]?: any
    a: string
    b: string
    c: string | undefined
    d: string | null
    e: string
    }
    )
    })

    // But if we do any kind of modification on them, like omitting a key that doesn't exist, it works
    test("maybe / optional type inference verification", () => {
    const T = types.model({
    a: types.string,
    b: "test",
    c: types.maybe(types.string),
    d: types.maybeNull(types.string),
    e: types.optional(types.string, "test")
    })

    interface ITC extends SnapshotIn<typeof T> {}
    interface ITS extends SnapshotOut<typeof T> {}

    assert(
    _ as Omit<ITC, "non-existent-property">,
    _ as {
    [$nonEmptyObject]?: any
    a: string
    b?: string
    c?: string | undefined
    d?: string | null
    e?: string
    }
    )

    assert(
    _ as Omit<ITS, "non-existent-property">,
    _ as {
    [$nonEmptyObject]?: any
    a: string
    b: string
    c: string | undefined
    d: string | null
    e: string
    }
    )
    })