Hi,

First of several major issues for system tests:

Steps to reproduce:

1. Check out Python 3 staging branch.
2. Apply fixes such as basestring to str.
3. Run system tests (scons systemTests).

Actual behavior:

appModuleHandler.doesAppModuleExist function throws AttributeError, causing system tests to fail.

Expected behavior:

System test passes.

System configuration

NVDA installed/portable/running from source:

Source

NVDA version:

Python 3 staging

Windows version:

Windows 10 Version 1903

Name and version of other software in use when reproducing the issue:

None

Other information about your system:

None

Other questions

Does the issue still occur after restarting your PC?

Yes

Have you tried any other versions of NVDA? If so, please report their behaviors.

Python 2: system test passes.

Additional context:

When system test spy is run, app module handler isn't initialized, causing importers (a private list) to remain uninitialized - remain None. Python 3 is strict about this. One solution is to catch attribute error in the affected function.

Thanks.