problems with branch identification and coverage #594
Description
Originally reported by Anonymous
See pytest-cov for history.
I have code that contains branches that are provably executed from output but show up in the coverage as missing. Working with the pytest-cov folks, I reduced the problem to a very simple yet verbose group of unit tests.
There are 4 tests (foo to foobar inclusive) that test the branch detection and coverage. All of the functions are the same with additional yet fixed complexity wrapping them. foo() is the basic if block. fooa() is an if block with the foo() if block contained within it. Other complexity is added (the for block seems to break things) to make the test fairly complete.
Ideally, the coverage should be 100% since it is basically the same if block. However, the ideal case is not the result. There are then sna() and snafu() that have changed the basic if block to if-else blocks and they do pass.
Here is the command line to run the test:
python3 -m pytest --cov=cov_test --cov-branch --cov-report term-missing PyScripts/cov_test.py
It produces these results:
============================= test session starts ==============================
platform linux -- Python 3.5.2, pytest-3.1.3, py-1.4.34, pluggy-0.4.0
rootdir: /home/niessner, inifile:
plugins: cov-2.5.1
collected 1 item s
PyScripts/cov_test.py .
----------- coverage: platform linux, python 3.5.2-final-0 -----------
Name Stmts Miss Branch BrPart Cover Missing
-------------------------------------------------------------------
PyScripts/cov_test.py 48 0 20 2 97% 18->21, 27->30
=========================== 1 passed in 0.03 seconds ===========================
Here is the test module:
def foo(states:[bool]):
if all(states):
print ('foo')
pass
return True
def foob (states:[bool]):
if True:
if all(states):
print ('foob')
pass
pass
return True
def fooba (states:[bool]):
for i in range(10):
if all(states):
print ('fooba')
pass
pass
return True
def foobar (states:[bool]):
if True:
for i in range(10):
if all(states):
print ('fooba')
pass
pass
pass
return True
def sna (states:[bool]):
for i in range(10):
if all(states):
print ('sna')
else: print ('ans')
pass
return True
def snafu (states:[bool]):
if True:
for i in range(10):
if all(states):
print ('snafu')
else: print ('ufans')
pass
pass
return True
def test():
assert foo([True,False])
assert foo([True,True])
assert foob([True,False])
assert foob([True,True])
assert fooba([True,False])
assert fooba([True,True])
assert foobar([True,False])
assert foobar([True,True])
assert sna([True,False])
assert sna([True,True])
assert snafu([True,False])
assert snafu([True,True])
return