1593562 - assertAndStrip is broken, causing browser_inspector-mutations-frameload.js to not test everything that it intends to

Status: RESOLVED DUPLICATE of bug 1652445

(DevTools :: Inspector, defect, P3)

Description

[Matt Woodrow (:mattwoodrow)]

In bug 1593560 I'm trying to enable DocumentChannel for data: URIs, which causes browser_inspector-mutations-frameload.js to intermittently fail (as it has previously in bug 1044272).

I believe this is because my patches change the load timing of data: URIs slightly (adds an extra IPDL round trip), so is exposing existing races. I haven't yet been able to reproduce locally unfortunately.

I am able to fairly reliably reproduce bug 1579945 (unexpected frameLoad in the inspector warning) with this test though.

Trying to debug this issue, I found that assertAndStrip is fairly broken.

Firstly, it compares mutations.length (the length of the array) to mutations.size (undefined!) to see if we successfully removed anything, which unconditionally succeeds.

Secondly, the intent of this function is to remove entries that matched what we're looking for, but instead it does a filter, so it instead returns only what we're looking for. After two checks, the mutations list is guaranteed to be empty, but we keep passing because of the first issue.

Fixing both of these then causes the tests to fail (even without my patches), because we're not actually getting the mutations we wanted (we only get documentUnload and childList).

I intend to disable the test for now since it's clearly buggy, and this bug can track fixing it.

Comment 1

[Alexandre Poirot [:ochameau]]

Bug 1593560, which Matt is looking at, is a platform refactoring related to Fission. So I'm triaging this bug accordingly.

Comment 2

[Chris Peterson [:cpeterson]]

Tracking Fission DevTools bugs for Fission Nightly (M6)

Comment 3

[Chris Peterson [:cpeterson]]

dt-fission-reserve bugs do not need to block Fission Nightly (M6).

Comment 4

[Chris Peterson [:cpeterson]]

Tracking dt-fission-reserve bugs for Fission MVP until we know whether they really need to block Fission or not.

Comment 5

[Chris Peterson [:cpeterson]]

Moving old "dt-fission-reserve" bugs to "dt-fission-future" because they don't block Fission MVP.

Comment 6

[Julian Descottes [:jdescottes]]

Removed the test in Bug 1652445