pytest, coverage.py, multi-line set/dict/generator comprehensinos

.coveragerc

[run]
source = test_foo
branch = True

[report]
show_missing = True

output.log

$ tox
py27 installed: coverage==4.2,py==1.4.31,pytest==2.9.2
py27 runtests: PYTHONHASHSEED='2822103878'
py27 runtests: commands[0] | coverage run -m pytest
===================================================== test session starts ======================================================
platform darwin -- Python 2.7.12, pytest-2.9.2, py-1.4.31, pluggy-0.3.1 -- /Users/andy/tmp/coverage-bug/.tox/py27/bin/python2.7
cachedir: .cache
rootdir: /Users/andy/tmp/coverage-bug, inifile: tox.ini
collected 1 items

test_foo.py::test_foo PASSED

=================================================== 1 passed in 0.01 seconds ===================================================
py27 runtests: commands[1] | coverage report --skip-covered -m --fail-under=100
Name          Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------
test_foo.py       4      0      5      1    89%   6->exit
ERROR: InvocationError: '/Users/andy/tmp/coverage-bug/.tox/py27/bin/coverage report --skip-covered -m --fail-under=100'
py35 installed: coverage==4.2,py==1.4.31,pytest==2.9.2
py35 runtests: PYTHONHASHSEED='2822103878'
py35 runtests: commands[0] | coverage run -m pytest
===================================================== test session starts ======================================================
platform darwin -- Python 3.5.2, pytest-2.9.2, py-1.4.31, pluggy-0.3.1 -- /Users/andy/tmp/coverage-bug/.tox/py35/bin/python3.5
cachedir: .cache
rootdir: /Users/andy/tmp/coverage-bug, inifile: tox.ini
collected 1 items

test_foo.py::test_foo PASSED

=================================================== 1 passed in 0.02 seconds ===================================================
py35 runtests: commands[1] | coverage report --skip-covered -m --fail-under=100
Name          Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------

1 file skipped due to complete coverage.
___________________________________________________________ summary ____________________________________________________________
ERROR:   py27: commands failed
  py35: commands succeeded
  
$ tox -- --assert=plain
py27 installed: coverage==4.2,py==1.4.31,pytest==2.9.2
py27 runtests: PYTHONHASHSEED='296090122'
py27 runtests: commands[0] | coverage run -m pytest --assert=plain
===================================================== test session starts ======================================================
platform darwin -- Python 2.7.12, pytest-2.9.2, py-1.4.31, pluggy-0.3.1 -- /Users/andy/tmp/coverage-bug/.tox/py27/bin/python2.7
cachedir: .cache
rootdir: /Users/andy/tmp/coverage-bug, inifile: tox.ini
collected 1 items

test_foo.py::test_foo PASSED

=================================================== 1 passed in 0.01 seconds ===================================================
py27 runtests: commands[1] | coverage report --skip-covered -m --fail-under=100
Name          Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------

1 file skipped due to complete coverage.
py35 installed: coverage==4.2,py==1.4.31,pytest==2.9.2
py35 runtests: PYTHONHASHSEED='296090122'
py35 runtests: commands[0] | coverage run -m pytest --assert=plain
===================================================== test session starts ======================================================
platform darwin -- Python 3.5.2, pytest-2.9.2, py-1.4.31, pluggy-0.3.1 -- /Users/andy/tmp/coverage-bug/.tox/py35/bin/python3.5
cachedir: .cache
rootdir: /Users/andy/tmp/coverage-bug, inifile: tox.ini
collected 1 items

test_foo.py::test_foo PASSED

=================================================== 1 passed in 0.01 seconds ===================================================
py35 runtests: commands[1] | coverage report --skip-covered -m --fail-under=100
Name          Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------

1 file skipped due to complete coverage.
___________________________________________________________ summary ____________________________________________________________
  py27: commands succeeded
  py35: commands succeeded
  congratulations :)

test_foo.py

def test_foo():
    # covered!
    assert {i for i in range(10)} == {i for i in range(10)}

    # "didn't finish the set comprehension"
    assert {i for i in range(10)} == {
        i for i in range(10)
    }

    # covered!
    assert True


def test_list_comprehension():
    assert {i for i in range(10)} == {i for i in range(10)}

    # "didn't finish the list comprehension"
    assert [i for i in range(10)] == [
        i for i in range(10)
    ]

    # covered!
    assert True

tox.ini

[pytest]
addopts = --strict -ra --tb=short -v

[tox]
envlist = py27,py36,py37
skipsdist = true
skip_install = true

[testenv]
deps =
    pytest
    coverage
commands =
    coverage run -m pytest []
    coverage report --skip-covered -m --fail-under=100