fix(firestore): normalize Firestore pointer path

[IchordeDionysos]

Description

Equality checking of references is not user input safe as the internal Pointer check unnormalized paths.

Related Issues

#2928

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[Ehesp]

Thanks for that, really good catch!

[IchordeDionysos]

Not sure if I should update the CHANGELOG or version as a version wasn't yet uploaded?

[Ehesp]

Should be ok (cc @Salakar) - we haven't cut a dev release yet and it's not a user facing change so should be good.

[Salakar]

Not sure if I should update the CHANGELOG or version as a version wasn't yet uploaded?

Ye as above, no need to worry about those, though if the behaviour was also incorrect on the previous Firestore before the rework then feel free to add it to the existing change log for the rework.

[IchordeDionysos]

@Salakar well, tested it on an older version, and it didn't work there either.

So I'll add it to the CHANGELOG. :) I hope I'll do it correctly :D

[IchordeDionysos]

Additional note:

With the implementation in the PR calling .path now always returns the path in the same format, which might be breaking for some users.

But I think is more in line with how the native libraries handle it. :)

print(Firestore.instance.collection('test').path);
print(Firestore.instance.collection('/test').path);

final snap = await Firestore.instance.document('/some/doc').get();
final ref = snap.data['referenceToOtherDoc'] as DocumentReference;
print(ref.path);

Printed originally:

test
/test
some/otherDoc

And now prints:

test
test
some/otherDoc

Web implementation:
I've checked how web handles it:

console.log(firebase.firestore().collection('test').path);
console.log(firebase.firestore().collection('/test').path);

prints out:

test
test

So I think we should be fine with the implementation of this PR.

[IchordeDionysos]

@Salakar After doing some research of the current behavior I think there should definitely be some entry in the CHANGELOG, as this

1. fixes the current behavior for equality checks and
2. might be a breaking change for some users if they do something like:

Firestore.instance.collection('/test').path == '/test' // Will now be false, instead of true

[Salakar]

LGTM