Fix#11929.
Figured out what's going on. We have the following collection tree:
```
<Dir pyspacewar>
<Dir src>
<Package pyspacewar>
<Package tests>
<DoctestModule test_main.py>
<DoctestItem pyspacewar.tests.test_main.doctest_main>
```
And the `test_main.py` contains an autouse fixture (`fake_game_ui`) that
`doctest_main` needs in order to run properly. The fixture doesn't run!
It doesn't run because nothing collects the fixtures from (calls
`parsefactories()` on) the `test_main.py` `DoctestModule`.
How come it only started happening with commit
ab63ebb3dc07b89670b96ae97044f48406c44fa0? Turns out it mostly only
worked accidentally. Each `DoctestModule` is also collected as a normal
`Module`, with the `Module` collected after the `DoctestModule`. For
example, if we add a non-doctest test to `test_main.py`, the collection
tree looks like this:
```
<Dir pyspacewar>
<Dir src>
<Package pyspacewar>
<Package tests>
<DoctestModule test_main.py>
<DoctestItem pyspacewar.tests.test_main.doctest_main>
<Module test_main.py>
<Function test_it>
```
Now, `Module` *does* collect fixtures. When autouse fixtures are
collected, they are added to the `_nodeid_autousenames` dict.
Before ab63ebb3dc, `DoctestItem` consults
`_nodeid_autousenames` at *setup* time. At this point, the `Module` has
collected and so it ended up picking the autouse fixture (this relies on
another "accident", that the `DoctestModule` and `Module` have the same
node ID).
After ab63ebb3dc, `DoctestItem` consults
`_nodeid_autousenames` at *collection* time (= when it's created). At
this point, the `Module` hasn't collected yet, so the autouse fixture is
not picked out.
The fix is simple -- have `DoctestModule.collect()` call
`parsefactories`. From some testing I've done it shouldn't have negative
consequences (I hope).
Ran Benita