Cannot console.log assertions because of proxies

[meeber]

Consider:

const {expect} = require("chai");

it("meep", () => {
  const myAssertion = expect(42).to.equal(42);

  console.log(myAssertion);
});

In Chai v3.5, the output is:

Assertion {
__flags: { ssfi: [Function], object: 42, message: undefined } }
✓ meep

1 passing (25ms)

But in the current version of Chai off Github, the output is:

1. meep

0 passing (13ms)
1 failing

1. meep:
   Error: Invalid Chai property: inspect
   at Error (native)
   at Object.getProperty [as get] node_modules/chai/lib/chai/utils/proxify.js:30:15
   at formatValue (util.js:343:19)
   at inspect (util.js:198:10)
   at exports.format (util.js:75:24)
   at Console.log (console.js:43:37)
   at Context.it (test/index.js:6:11)

Possible solution:

Add inspect as a blacklisted property here. then already exists as a blacklisted property for promise support. inspect is a standard property in Node, as noted in #727 (comment).

Rather than hard-coding the blacklist, it might be more appropriate to refactor the blacklist to be a new Chai config value.

[keithamus]

Just wanna say btw, aside from this ticket, thank you for being an awesome chai maintainer! It really shows that you care and thats super important. You're my hero ❤️

[meeber]

IF CARTOON LEMURS COULD BLUSH

[lucasfcosta]

Hello everyone, I'm back!
Keith's words are the same as mine, you're really awesome buddy!

Also, blacklisting values on the Chai config really seems more appropriate than hard-coding values.

[meeber]

@lucasfcosta Welcome back sir. You've been missed.

NOW GET TO WORK :D

AND ABSOLUTELY NO MORE VACATIONS EVER

(By the way, @keithamus @lucasfcosta, I'll be on vacation with limited connectivity Aug 18th - Sept 4th)

[lucasfcosta]

I missed you too, especially your funny code reviews.
Have a nice vacation, make sure to eat lots of pizza and have lots of fun 😄

[meeber]

Welcoming PRs on this. See #770 for inspiration on how to go about this type of change.

What we're looking for is:

• New Chai config value named something like proxyExclude, proxyBlacklist, proxyExcludedKeys, or proxyExcludedProperties. Not sure which is best. Maybe something else not listed.
• It should be an array of strings (property keys) with default values of "then" and "inspect".
• Any property key in this array should be excluded from the proxy property check here, replacing the current hard-coded value of "then".
• The in-file documentation should note that this setting only applies to users with useProxy enabled, and only in environments where proxies are supported.
• A couple of tests should be added to show that assertions don't contain a then or inspect property and yet accessing myAssertion.then and myAssertion.inspect doesn't throw an error despite useProxy being enabled in an environment where proxies are supported.