[webkit-dev] platform-specific differences in test case inputs

Oliver Hunt oliver at apple.com
Tue Sep 18 12:43:26 PDT 2012

JSC's SerializedScriptValue has always been versioned (having learned the horror of no versioning with localStorage :( )

Newer formats (obviously) can't be read by older clients, but the serialisation is intentionally forwards compatible.


On Sep 18, 2012, at 12:36 PM, Adam Barth <abarth at webkit.org> wrote:

> This is an interesting case because it's important for the
> serialization format to be consistent across time (so that an
> IndexedDB created at one point in time can work at another point in
> time), but it's not important to be consistent across embedders
> (because IndexedDB created by Safari don't need to be readable by
> Chrome and vice versa).
> Perhaps we shouldn't use LayoutTests to test this functionality.
> Instead, it might make more sense to use API-level tests that check
> that a particular embedder API is stable and working as expected.
> Adam
> On Tue, Sep 18, 2012 at 12:19 PM, Alec Flett <alecflett at chromium.org> wrote:
>> Background: some of the storage systems use SerializedScriptValue to persist
>> structured-clonable objects
>> (http://www.w3.org/TR/html5/common-dom-interfaces.html#safe-passing-of-structured-data)
>> - most of this is implemented in a V8 or JSC-specific implementation of
>> SerializedScriptValue.
>> I'm adding tests for the actual values stored with SerializedScriptValue so
>> that we can move forward with serialization changes without breaking
>> backwards compatibility.
>> So many of my js tests boil down to:
>> testSerialization({}, [0x01ff, 0x003f, 0x7b6f, 0x0000]);
>> Which makes sure that these two representations are equivalent by going in
>> both directions.
>> The issue I'm hitting is that JSC has a different implementation with a
>> different storage format, and the serialization/deserialization between the
>> two storage formats is not compatible - the above code works great on V8 but
>> JSC uses different bytes.
>> I can't address this with just expectations files (i.e. only check that {}
>> serializes to some byte array, and have different expectations depending on
>> the port) because I need to check that specific inputs (such as old V8-based
>> formats) can also deserialize back into the right native objects.
>> What I kind of want is something like:
>> #ifdef JSC
>> <script src="serialized_script_tests_jsc.js"> </script>
>> #endif
>> #ifdef V8
>> <script src="serialized_script_tests_v8.js"> </script>
>> #endif
>> Thoughts?
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