Config schemas are enforced for disabled rules

[not-an-aardvark]

Tell us about your environment

• ESLint Version: master
• Node Version: 7.2.0
• npm Version: 3.10.9

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.

I created a rule with a required schema, like this:

// "example-rule"
module.exports = {
    meta: {
        schema: {
            // At least one option must be provided
            type: "array",
            minItems: 1
        }
    },
    create(context) {}
};

I ran the rule on some code in foo.js with three different sets of options:

eslint foo.js --rule 'example-rule: [error, 4]' # case 1
eslint foo.js --rule 'example-rule: error'      # case 2
eslint foo.js --rule 'example-rule: off'        # case 3

What did you expect to happen?

In Case 1, I expected ESLint to run to completion without reporting an error, because a valid schema was provided.

In Case 2, I expected ESLint to report a schema error, because an invalid schema was provided (it was missing an option).

In Case 3, I expected ESLint to run to completion without reporting an error. The rule is disabled, so I shouldn't have to provide a schema while disabling it (e.g. example-rule: [off, 4])

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

ESLint worked as expected in Case 1 and Case 2, but it reported a schema error in case 3.

eslint foo.js --rule 'example-rule: off'
CLI:
	Configuration for rule "example-rule" is invalid:
	Value "" has less items than allowed.

Error: CLI:
	Configuration for rule "example-rule" is invalid:
	Value "" has less items than allowed.

    at Object.validateRuleOptions (/path/to/eslint/lib/config/config-validator.js:115:15)
    at CLIEngine.Object.keys.forEach.name (/path/to/eslint/lib/cli-engine.js:476:19)
    at Array.forEach (native)
    at new CLIEngine (/path/to/eslint/lib/cli-engine.js:475:43)
    at Object.execute (/path/to/eslint/lib/cli.js:169:28)
    at process.stdin.pipe.text (/path/to/eslint/bin/eslint.js:59:32)
    at ConcatStream.<anonymous> (/path/to/eslint/node_modules/concat-stream/index.js:36:43)
    at emitNone (events.js:91:20)
    at ConcatStream.emit (events.js:185:7)
    at finishMaybe (/path/to/eslint/node_modules/concat-stream/node_modules/readable-stream/lib/_stream_writable.js:475:14)