Hey @meeber, thank you very much for taking the time to do this!

I must admit, I am a bit puzzled by the meaning difference between deep and nested. If I understand properly, .deep.property acts similarly to .deep.equal (i.e. deep equal a specific property of an array/object) while .nested.property will follow the current behavior of .deep.property (i.e. traverse the given path to shallowly assert a property of an array/object). Am I in the wrong?

If I am correct, then I think I will need to add test cases to match the new behavior of .deep.equal, and potentially some code as well.

Do you know what is the timeframe of v4? That will mean releasing a 2.0.0 version of chai-immutable.
Since Node.js maintenance for v0.12 ends end of this year, I was planning to release a 2.0.0 anyway, dropping support of Node.js v0.10 and v0.12 (mostly meaning removing them from Travis CI / AppVeyor and using arrow functions, let and const). But if Chai v4 is around the corner, I should wait for it to bundle both breaking upgrades together.

Regarding breaking changes, do you think chaijs/chai#744 is going to affect this plugin?

Summary of what needs to be done for Chai v4

All details at chaijs/chai#781.
I am trying to list necessary changes only. All nice additions that can be made thanks to v4 will go into GitHub issues.

• Replace .deep.property with .nested.property Breaking: Rename .deep.property to .nested.property chaijs/chai#757
• Changes around .not.property if necessary Breaking: Change .not.property(name, val) behavior chaijs/chai#744
• Changes around fixes made to .include if necessary Breaking: Fix .include to always use strict equality chaijs/chai#760 It seems to me like it's not affecting this project I don't believe any change was required, but I added a few tests at Add tests around include and deep equality #147.
• Port additions of .own to this plugin Refactor ownProperty chaijs/chai#810 Will ignore for now, we'll see if anything is required later
• Fix case of results coming from _.test() type-detect@v3.0.0
• Update peerDependency to >= 4 (or >= 4.0.0?)
• Bump devDependency

You're correct about nested.property and deep.property. The new deep.property(name, val) performs deep equality comparison just like deep.equal, whereas the new nested.property allows for special syntax such as nested.property("zoo.lions[5].name", "tony") to dig down into an object/array. (Edit: they can be combined too via deep.nested.property)

One of the goals of Chai going forward is for keywords to have consistent meanings across assertions, so it's important for deep to have the same meaning when used with property as it does with equals and other assertions. Unfortunately, this means a breaking change :(

Not sure about timeframe of official release. I'm guessing mid-to-late January at the earliest. We're planning on dropping support for Node v0.10 and 0.12 as well.

Regarding #744: Ah yes, it looks like that PR might impact this plugin too (although it didn't break any tests). Basically, not.property(name, val) used to mean "assert that something has a name property but it doesn't equal val". Now, it instead means "assert that something doesn't have a name property equal to val".

You're correct about nested.property and deep.property. The new deep.property(name, val) performs deep equality comparison just like deep.equal, whereas the new nested.property allows for special syntax such as nested.property("zoo.lions[5].name", "tony") to dig down into an object/array. (Edit: they can be combined too via deep.nested.property)

Sounds good, and what I gathered, including the combination of both. I have created an issue to support .deep.property in this plugin after Chai v4 and this PR land: #75.

Not sure about timeframe of official release. I'm guessing mid-to-late January at the earliest. We're planning on dropping support for Node v0.10 and 0.12 as well.

Great timing for v2 of this plugin then: #74.

Regarding #744: Ah yes, it looks like that PR might impact this plugin too (although it didn't break any tests). Basically, not.property(name, val) used to mean "assert that something has a name property but it doesn't equal val". Now, it instead means "assert that something doesn't have a name property equal to val".

Well, that's bad if no tests were broken...
Tests around .not + .property are here, here, here, here, here and here.
Essentially, I do not have tests for .not + .property that test against a value and are not using .deep.
I will probably have to write tests for this prior to moving to Chai v4 as behavior will change and I need to make sure this is controlled. Essentially, I need to come up with tests that pass on the current version of Chai and break with v4.

@astorije I've updated this PR for the release of Chai v4.0. As mentioned before, this does seem like a breaking change for this plugin, so I've updated the package.json accordingly.

@astorije Chai 4 has been released. Is there is a plan to release this soon?

Bump! Any timeline for merging this?

Are there any pending issues which the community could solve to release Chai v4 compatible version?

Hey guys, sorry for this awfully long silence! I got very busy with life and other OSS projects, and didn't give enough love to chai-immutable.
I am planning to get back to this soon, to work on chai-immutable v2.0.0, which among other things will support Chai v4.

In the meantime, I understand how unacceptable it is for a library one relies on to stale like that, and I do apologize for it. To help ease the pain, I have just released v2.0.0-alpha.1 on npm, but careful, it is nothing more than master + this unreviewed PR. It is simply a temporary measure so you can get unstuck on your projects without heavily relying on me and on v2.0.0.

Does this help? Let me know if there is anything short-term I can do if necessary.

To anyone who needs chai-immutable to speak Chai v4, until I am done with the v2 of this plugin, you can use npm install chai-immutable@next.

Alright, let's make this happen. I'll merge it as-is, and if there are any issues, I'll address them later. It's been long enough, I don't have any excuses anymore 😅

Hey @artursvonda and @myklt, I have just released v2.0.0-rc.2 which hopefully is the last step before full Chai v4 support (finally!). Mind giving it a shot and letting me know if it works as expected for you?