fix(eslint-plugin): [type-annotation-spacing] report excess spaces as error

[darcien]

Fixes #1001

[typescript-eslint]

Thanks for the PR, @darcien!

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[bradzacher]

code itself looks good, but we should probably handle extra spacing on both sides of the delimiter.

[darcien]

code itself looks good, but we should probably handle extra spacing on both sides of the delimiter.

Aaah right, I'll update it.

[darcien]

For the tests, I'm not sure how many test cases I should add though.

If I added too many, the test will be failing.

Something like this:

Summary of all failing tests
 FAIL  tests/rules/type-annotation-spacing.test.ts
  ● Test suite failed to run

    TypeScript diagnostics (customize using `[jest-config].globals.ts-jest.diagnostics` option):
    tests/rules/type-annotation-spacing.test.ts:1044:11 - error TS2322: Type 'string' is not assignable to type '"expectedSpaceAfter" | "expectedSpaceBefore" | "unexpectedSpaceBefore"'.

    1044           messageId: 'unexpectedSpaceBefore',
                   ~~~~~~~~~

      ../../node_modules/@typescript-eslint/experimental-utils/dist/ts-eslint/RuleTester.d.ts:21:5
        21     messageId: TMessageIds;
               ~~~~~~~~~
        The expected type comes from property 'messageId' which is declared here on type 'TestCaseError<"expectedSpaceAfter" | "expectedSpaceBefore" | "unexpectedSpaceBefore">'

[bradzacher]

It's a really weird error, I know - it's a weird way that typescript reports the error.
That type error usually occurs because there is something wrong with the test you've added - either there's a typo in a prop name, a missing property, or similar.
I usually narrow it down by commenting out tests one-by-one until I find out which one has the error.

[armano2]

@darcien i did some testing and this issue with types got solved (is no longer present in experimental-utils/typescript)

after running this rule it seems to try to remove new lines after : (in our case this is conflicting with prettier)

      node:
        | TSESTree.VariableDeclarator
        | TSESTree.Parameter
        | TSESTree.ClassProperty,

becomes:

      node: | TSESTree.VariableDeclarator
        | TSESTree.Parameter
        | TSESTree.ClassProperty,

[bradzacher]

in our case this is conflicting with prettier

We should probably add the prettier/@typescript-eslint config to our codebase.
Prettier is not expected to play nicely with formatting rules, and as such this conflict is fine.