385869 - reftest comparing dataURI to identical dataURI does not pass equality test

Status: REOPENED

(Testing :: Reftest, defect)

Description

[Ray Kiddy]

Attachment: a reftest manifest file

Running on trunk build of firefox, fetched yesterday.

See the enclosed reftest.list. It just contains:

== (a data URI) (the same data URI)

A data URI, when compared to itself, should pass a test for being equal, yes?

Comment 1

[Adam Guthrie]

Why do you have "==" on the end of each data: URI? Does it work when you remove those?

Comment 2

[Ray Kiddy]

The "==" on the end of the data URI is there because that is what reftest gave me. When there is a failure in a reftest test, it dumps out the data URI. I took a data URI that it dumped out and pasted it onto one line, twice, with a "==" at the beginning of the line.

I have an edit to reftest that lets it load png image files and successfully compares a rendered page and a PNG file. However, it as suggested that we should use data URIs instead of PNG files. Taking this to heart, I thought that using data URIs would work. However, I find that they do not.

I tried taking the "==" off the end of each URI and it still failed.

Comment 3

[Adam Guthrie]

Yeah, sorry. Gavin tells me the "==" is added for padding.

Some of the existing tests use an <img> element with the src attribute being a data URI [0]. Would this be an acceptable alternative?

[0] http://mxr.mozilla.org/seamonkey/source/layout/reftests/bugs/370629-1.html

Comment 4

[Ray Kiddy]

It does work to put the data URI into an image tag. It is a bit awkward, though.

Comment 5

[Ray Kiddy]

This is too much like this other bug to keep open. Closing as dupe.

Comment 6

[Jesse Ruderman]

I don't think this is a dup of bug 376628.  Bug 376628 was about comparing HTML to an image and occurs because of padding added to the image.  This bug is about comparing an image to an identical image, and we don't know what causes it.

Comment 7

[Ray Kiddy]

Using the <img> tag does work in some cases but it does not in others. If there is a colored background to a page, for example, the reftest image crops the background color at the edge of the image.

If your page has no background, then one does seem to be able to use the <img> tag workaround, but it is not a very good work-around. Attaching html page that demonstrates the problem.

Comment 8

[Ray Kiddy]

Attachment: html file that cannot be "snapped" for data URI in <img>