Android 7.0 xpcshell tests run against the fennec apk. Structurally, it is easy to run against geckoview, but when I initially tried, there were unexplained test failures.

Demonstration of the failures with geckoview apk:

https://treeherder.mozilla.org/#/jobs?repo=try&tier=1%2C2%2C3&revision=97c7130f658f9f7529e21074c5ea5a408cb56470

I have verified the same test failures (like netwerk/test/httpserver/test/test_byte_range.js) running locally against the 7.0 x86_64 emulator. In that environment, I have verified that the same libraries and the same modules (like httpd.js) are pushed to device regardless of apk. Of course the apk differs (used for --greomni).

The failure in the geckoview run of netwerk/test/httpserver/test/test_byte_range.js occurs because the GetService call at

https://searchfox.org/mozilla-central/rev/6c9f60f8cc064a1005cd8141ecd526578ae9da7a/netwerk/test/httpserver/httpd.js#2767

fails:

JavaScript error: resource://gre/modules/XPCOMUtils.jsm, line 433: NS_NOINTERFACE: 

With work-arounds for bug 1553943 and bug 1554326, only 2 tests fail (bug 1554276):

https://treeherder.mozilla.org/#/jobs?repo=try&tier=1%2C2%2C3&revision=d70bd04d02a9fd42a1086677a821b9883a2dcb01

:snorp - When you get a chance, look at the dependent bugs please.

This is blocking bug 1566423 and the fennec/geckoview issue is causing confusion: Let's try to sort this out soon. All the issues are documented in the dependent bugs, but we need decisions about how to resolve those.

(In reply to Geoff Brown [:gbrown] from comment #5)

:snorp - When you get a chance, look at the dependent bugs please.

I've r?'d you with proposed solutions for the remaining issues.

Switch the target apk for Android 7.0 xpcshell-test to geckoview. At the same time,
update the mach command for local runs to select the geckoview apk rather than the
fennec one, by default.

https://hg.mozilla.org/mozilla-central/rev/6025ec39360f