bug(cdk/coercion): coerceNumberProperty(thing, undefined) has invalid implementation or signature

[urugator]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

coerceNumberProperty(thing, undefined) works the same way as coerceNumberProperty(thing), so it yields 0 if the thing isn't coercible to number. This is quite unexpected, because:

1. In all other cases the fallback argument is respected.
2. The return type is different: coerceNumberProperty(thing, undefined) returns number | undefined, even though the implementation always yields number.

Reproduction

StackBlitz link:
Steps to reproduce:
1.
2.

Expected Behavior

Fallback argument should be respected even for undefined.

Actual Behavior

undefined isn't respected as a fallback.

Environment

• Angular: 17.0.6
• CDK/Material: 17.1.0
• Browser(s): *
• Operating System (e.g. Windows, macOS, Ubuntu): *

[GiftLanga]

I'll work on this issue if no one working on it.

[GiftLanga]

@urugator it's not possible to set the fallback value as undefined as you can see on the implementation the default fallback value is 0.

I suggest that you return a string as a work around like this.
coerceNumberProperty<String>(value, 'undefined')

[urugator]

the implementation the default fallback value is 0.

Yes and the issue states that the implementation or signature is not correct.
Either the implementation should check arguments.length or the return type of coerceNumberProperty(x,undefined) should resolve to number. Instead it matches coerceNumberProperty<D>(value: any, fallback: D): number | D overload, so the return type resolves to number | undefined, which makes you believe it returns undefined when value is not coercible to number. I am just repeating what is already noted in the OP.

[GiftLanga]

It is correct that the return type of coerceNumberProperty(x,undefined) is number | undefined because of this definition coerceNumberProperty<D>(value: any, fallback: D): number | D as you stated.

However as I said it is not possible to return undefined when the fallback default value is 0. The only way I can think of is to set the fallback default value to undefined, but that will break the tests.

A better recommendation would be to use null instead, because it's an assignment value.
coerceNumberProperty(value, null)

[urugator]

it is not possible to return undefined when the fallback default value is 0.

export function coerceNumberProperty(value: any, fallbackValue: any) {
  return _isNumberValue(value) ? Number(value) : arguments.length === 2 ? fallbackValue : 0;
}
// coerceNumberProperty('foo') === 0
// coerceNumberProperty('foo', undefined) === undefined

Note that implementation signature is not visible from the outside, so this doesn't break the API, quite the opposite - the implementation is changed to match these 2 overload signatures, that are actually visible from the outside.

[GiftLanga]

Ohh okay I see, can you make the PR.

[urugator]

@crisbeto Thank you for picking this up, but I think you forgot to remove the default value in argument fallbackValue = 0 => fallbackValue. JS treats undefined as not provided:

function foo(x=0) {
    console.log(arguments.length, x);
}
foo(); // 0 0
foo(undefined); // yields 1 0  but we want 1 undefined

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