Improve report location calculations

[gustavnikolaj]

Given this example:

import expect from '../../../../testUtils/unexpectedReact';
import React from 'react';
import FormattedSize from '../FormattedSize';

it('should render 123 bytes as 0.1KB', () => expect(
    <FormattedSize size={123} />,
    'to render as',
    <span>0.1 KB</span>
));

it('should render 1241240 bytes as 1.2MB', () => expect(
    <FormattedSize size={1241240} />,
    'to render as',
    <span>1.2 MB</span>
));

Prettier wants it formatted as:

import expect from '../../../../testUtils/unexpectedReact';
import React from 'react';
import FormattedSize from '../FormattedSize';

it('should render 123 bytes as 0.1KB', () =>
    expect(<FormattedSize size={123} />, 'to render as', <span>0.1 KB</span>));

it('should render 1241240 bytes as 1.2MB', () =>
    expect(
        <FormattedSize size={1241240} />,
        'to render as',
        <span>1.2 MB</span>
    ));

But running eslint gives me the following report:

$ ./node_modules/.bin/eslint src/common/components/FormattedSize/__tests__/FormattedSize-test.js 

./src/common/components/FormattedSize/__tests__/FormattedSize-test.js
  5:45  error  Follow `prettier` formatting (expected '\n' but found ' ')  prettier/prettier

I expected an error to be reported on both line 5 and 11, not just line 5. If I proceed to actually run prettier, both are fixed up as expected.

Other rules continue to work as expected, but this plugin and it's rule will only report the first problem.

[not-an-aardvark]

This is working as intended, although there is some room for improvement. The plugin just compares the original text to the prettier-formatted text, and reports an error at the first location where the two strings differ. At the moment, it doesn't generate line-by-line diffs.

I'm open to a PR to compare the two strings more intelligently.

[gustavnikolaj]

I don't see how the location problem is related to my initial report 😄

I think the wording makes me expect that it is an exhaustive report that I get, and it is not in sync with my expectations as a user, that I get an error report worded like that, and only one of them.

I realize why it's hard to do anything about, but an alternative solution that wouldn't cause this user experience WTF moment could be to just have it fail with an error on line 1 character 1:

This file contains code that is different to the output of prettier.

[not-an-aardvark]

Hmm, I'm not sure I want to just output an error on line 1 character 1, because in some cases maybe the error message is useful (e.g. if someone is missing a semicolon). Making the error message clearer seems like it could be a good idea though.

[zertosh]

This will be fixed once #21 is merged.

[zertosh]

I just published eslint-plugin-prettier@2.1.0 which fixes this