Update: Allow space-unary-ops to handle await expressions

[not-an-aardvark]

What is the purpose of this pull request? (put an "X" next to item)

[ ] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[x] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

Please check each item to ensure your pull request is ready:

• I've read the pull request guide
• I've included tests for my change
• I've updated documentation for my change (if appropriate)

See #7101 for context. Now that async functions can be parsed by acorn, this fix allows space-unary-ops to detect await expressions.

What rule do you want to change?

space-unary-ops

Does this change cause the rule to produce more or fewer warnings?

More, although it is not expected to break anyone's code since await expressions couldn't be parsed by Espree until a few hours ago.

How will the change be implemented? (New option, new default behavior, etc.)?

This would allow await expressions to be checked by space-unary-ops, in the same manner as yield expressions.
This would work the same way as yield currently does, i.e. await would be part of the words option, and it would be possible to specify {await: true} or {await: false} as an override.

Please provide some example code that this change will affect:

/* eslint space-unary-ops: 2 */

async function foo() {
  await(5); // error: Unary word operator 'await' must be followed by whitespace.
  await (5); // ok
}

/* eslint space-unary-ops: [2, {"words": false}] */

async function foo() {
  await(5); // ok
  await (5); // error: Unexpected space after unary word operator 'await'.
}

What does the rule currently do for this code?

await expressions are currently not linted at all.

What will the rule do after it's changed?

The rule will report await expressions that are not followed by a space (in the same way that it currently reports yield expressions).

What changes did you make? (Give an overview)

(Implements the behavior above)

Is there anything you'd like reviewers to focus on?

Would this change break cause errors for users who have been using babel-eslint? If so, is it still semver-minor?

[eslintbot]

LGTM

[mention-bot]

@not-an-aardvark, thanks for your PR! By analyzing the annotation information on this pull request, we identified @vitorbal, @qmmr and @gyandeeps to be potential reviewers

[eslintbot]

LGTM

[mysticatea]

LGTM, thank you!

[mysticatea]

Ah, this is an enhancement of space-unary-ops.
So it needs 3 👍s from the team.
I'm a champion.

• AwaitExpression production belongs to UnaryExpression production in the spec: https://tc39.github.io/ecmascript-asyncawait/#UnaryExpression
• space-unary-ops has been checking yield expressions. So I guess that people expect that the rule checks await expressions also since those are similar.

[platinumazure]

Endorsed via 👍 to the original PR comment.

[qmmr]

LGTM 👍