fix(types): getState is not bound to MiddlewareAPI

[janeklb]

PR Type

Does this PR add a new feature, or fix a bug?

Fixes a type bug

Why should this PR be included?

The getState function provided by MiddlewareAPI is not bound to any object, and as such it can be used freely as in the examples.

The MiddlewareAPI type does not make this explicit, and typescript linters can report this as problematic usage.

Checklist

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [ ] Is there an existing issue for this PR?
  • link issue here
• [x] Have the files been linted and formatted?
  • there's a file that needs formatting, but is outside the scope of my change: docs/usage/deriving-data-selectors.md
• [x] Have the docs been updated to match the changes in the PR?
  • No updates needed IMO
• [x] Have the tests been updated to match the changes in the PR?
  • No new tests added - the linting rules required to
• [x] Have you run the tests locally to confirm they pass?

Bug Fixes

What is the current behavior, and the steps to reproduce the issue?

• Enable the @typescript-eslint/unbound-method linting rule
• Load up one of the examples

  const middleware: Middleware<unknown, unknown> =
  ({ getState }) =>
  (next) =>
  (action) => {
    // ...
  };

• The linter will report that the rule is being violated

What is the expected behavior?

getState can be used with the linting rule enabled and not produce errors

How does this PR fix the problem?

Fixes the signature of getState

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[timdorr]

This should have some sort of test to go along with it. That will prevent a regression in the future.

[janeklb]

This should have some sort of test to go along with it. That will prevent a regression in the future.

I'm able to create a test if we revert to

export interface MiddlewareAPI<D extends Dispatch = Dispatch, S = any> {
  dispatch: D
  getState(this: void): S
}

however, with the current signature (getState: () => S), I can't find a way to do it. @EskiMojo14 can you advise?

[janeklb]

This should have some sort of test to go along with it. That will prevent a regression in the future.

I'm able to create a test if we revert to

export interface MiddlewareAPI<D extends Dispatch = Dispatch, S = any> {
  dispatch: D
  getState(this: void): S
}

however, with the current signature (getState: () => S), I can't find a way to do it. @EskiMojo14 can you advise?

Never mind -- found something that covers the bases, I think.

[timdorr]

Thanks!