Report hasn't the TOTAL line if one file is tested only

[mosling]

Describe the bug
A very simple setup, I have one python script (script.py) and a test for this script (script_test.py).

The result for coverage run -m pytest and coverage report is

Name            Stmts   Miss  Cover
-----------------------------------
adder.py            2      0   100%
adder_test.py       7      1    86%
-----------------------------------
TOTAL               9      1    89%

But the same with coverage run --omit='*_test.py' -m pytest and coverage report results into

Name       Stmts   Miss  Cover
------------------------------
adder.py       2      0   100%

The summary line with TOTAL is missing
I use GitLab and look for the TOTAL line to catch the test coverage.

To Reproduce
How can we reproduce the problem? Please be specific.

1. Python 3.8.0
2. Coverage.py, version 5.0.3 with C extension
3. Example project at https://github.com/mosling/coverage-example

Expected behavior
TOTAL line should appear in every case. It is important for data processing to have the same behavior in each case, I never see the output ;-)

[nedbat]

This has been reported before, in #732. My advice there was to simply read the last word on the last line of the report, which will be what you want in all cases. But now, as of version 5.0, there's a better answer: use the "coverage json" report, and read the number programmatically.

[nedbat]

@mosling Also, I'm curious what you use the total number for. Maybe there's a better way we can provide it. Do you know about the --fail-under option?

[nedbat]

Now with #1091, the TOTAL line is always output.

[nedbat]

This is now released as part of coverage 5.4.