messageId doc examples throw during testing.

[betaorbust]

Tell us about your environment

• ESLint Version: 4.15+
• Node Version: 8.9.3
• npm Version: 5.5.1

What parser (default, Babel-ESLint, etc.) are you using?
default

Please show your full configuration:
N/A

What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.
Ran the code provided in the messageId section of the Working with Rules page.
Recreated below:

lib/rules/no-foo.js

'use strict';
module.exports = {
    meta: {
        messages: {
            avoidName: "Avoid using variables named '{{ name }}'"
        }
    },
    create(context) {
        return {
            Identifier(node) {
                if (node.name === "foo") {
                    context.report({
                        node,
                        messageId: "avoidName",
                        data: {
                            name: "foo",
                        }
                    });
                }
            }
        };
    }
};

tests/lib/rules/no-foo.js
Updated require path which was var rule = require('../../../lib/rules/no-insecure-random'); which seems unrelated to this example.

'use strict';
// In your tests:
var rule = require('../../../lib/rules/no-foo');
var RuleTester = require('eslint').RuleTester;

var ruleTester = new RuleTester();
ruleTester.run('my-rule', rule, {
  valid: ['bar', 'baz'],

  invalid: [
    {
      code: 'foo',
      errors: [
        {
          messageId: 'foo',
        }
      ]
    }
  ]
});

What did you expect to happen?
It should work out of the box more or less.

What actually happened? Please include the actual, raw output from ESLint.

 1 failing

  1) my-rule invalid foo:
     AssertionError [ERR_ASSERTION]: Invalid messageId 'foo'. Expected one of ['avoidName'].
      at testInvalidTemplate (node_modules\eslint\lib\testers\rule-tester.js:508:40)
      at Context.RuleTester.it (node_modules\eslint\lib\testers\rule-tester.js:581:25)

[platinumazure]

Hi @betaorbust, thanks for the issue! I agree 100%, those docs need tweaking. Would you like to submit a pull request?

[betaorbust]

Unfortunately, while putting together my PR for this, I ran into a much bigger problem in how the messageId feature currently works.

See #9890 for more details.