1115275 - window.indexedDB can't be overwritten and replace with a mock

Status: RESOLVED INVALID

(Core :: Storage: IndexedDB, defect)

Description

[Tim Guan-tin Chien [:timdream] (please needinfo)]

STR:

1. window.indexedDB = {}
2. console.log(window.indexedDB);

Expected:

1. Object {  }

Actual:

1. IDBFactory {  }

Note:

In Gaia we have mock (and mock helpers) for us to mock many of the APIs in unit tests. Because of this bug, we have to create special rules for window.indexedDB by replacing it's method instead (e.g. [1]). It would be better if this can be fixed and we could simply replace the instance.

[1] https://github.com/mozilla-b2g/gaia/blob/d55d1d5f39bd338ab2d298823aab1121e3d73fef/apps/keyboard/test/unit/mock_indexeddb.js#L210-L215

Comment 1

[Masatoshi Kimura [:emk]]

Workaround:
1. delete window.indexedDB
2. window.indexedDB = {}

Comment 2

[Masatoshi Kimura [:emk]]

According to the indexedDB spec [1], the indexedDB property is read only. So this is expected.
But the property descriptor
  Object { configurable: true, enumerable: true, get: indexedDB(), set: undefined }
was different from what I expected:
  Object { configurable: true, enumerable: true, value: IDBFactory, writable: true }

[1] http://www.w3.org/TR/IndexedDB/#idl-def-IDBEnvironment

Comment 3

[Masatoshi Kimura [:emk]]

>  Object { configurable: true, enumerable: true, value: IDBFactory, writable: true }
Correction:
  Object { configurable: true, enumerable: true, value: IDBFactory, writable: false }

Comment 4

[Masatoshi Kimura [:emk]]

>   Object { configurable: true, enumerable: true, get: indexedDB(), set:

This was also expected:
https://heycam.github.io/webidl/#es-attributes

So comment #1 was a proper way to replace the indexedDB property rather than a workaround.

If you think the indexedDB property should be [Replaceable], please file a spec bug.

Comment 5

[Tim Guan-tin Chien [:timdream] (please needinfo)]

Thanks, bug 1118648 filed against Gaia instead.