feat[isRecordObjectOf]: checks own symbol key properties

[Milly]

Contains bug fixes. See below comments.

[Milly]

@lambdalisue
I have some questions regarding implementation.

isRecordObjectOf() and isRecordOf() walk the prototype chain of the target object and test all enumerable properties excluding Symbols.

Example:

class Foo {
  a = "a";
}
const foo = new Foo(); // foo has no own properties.
isRecordOf(is.String)(foo); // true
isRecordOf(is.Number)(foo); // false

1. Is this the intended behavior?
2. Should Symbols be tested up the prototype chain as well?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.05%. Comparing base (4ec8855) to head (27f86b1).

Additional details and impacted files

@@                  Coverage Diff                   @@
##           symbol-properties-wip     #110   +/-   ##
======================================================
  Coverage                  98.04%   98.05%           
======================================================
  Files                         50       50           
  Lines                        817      821    +4     
  Branches                      88       89    +1     
======================================================
+ Hits                         801      805    +4     
  Misses                        16       16           

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[lambdalisue]

1. Is this the intended behavior?

No. Because TypeScript's behavior is different

class Foo {
  a = "a";
}
const _foo: Record<PropertyKey, string> = new Foo();
const _bar: Record<PropertyKey, string> = { a: "a" };

2. Should Symbols be tested up the prototype chain as well?

Yes. Because TypeScript's behavior is so

const s = Symbol("symbol");
const _foo: Record<PropertyKey, string> = { a: "a", [s]: "b" };
const _bar: Record<PropertyKey, string> = { a: "a", [s]: 0 };

[Milly]

@lambdalisue
I expected the answers to 1 and 2 to be the same.
I wanted to know whether to implement both string keys and symbol keys by "checking only the own properties" (No, No) or by "following the prototype chain and checking everything" (Yes, Yes).

Isn't the second example like this?

const s = Symbol("s");
class Foo {
  [s] = "a";
}
const foo = new Foo();
isRecordOf(is.String)(foo); // true?
isRecordOf(is.Number)(foo); // false?

[Milly]

both string keys and symbol keys by "following the prototype chain and checking everything" (Yes, Yes).

I fixed this behavior like.

[lambdalisue]

LGTM