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# Demonstrate some issues with coverage.py branch testing.
def my_function(x):
"""This isn't real code, just snippets..."""
# An infinite loop is structurally still a branch: it can next execute the
# first line of the loop, or the first line after the loop. But
# "while True" will never jump to the line after the loop, so the line
# is shown as a partial branch:
i = 0
while True:
print "In while True"
if i > 0:
break
i += 1
print "Left the True loop"
# Notice that "while 1" also has this problem. Even though the compiler
# knows there's no computation at the top of the loop, it's still expressed
# in byte code as a branch with two possibilities.
i = 0
while 1:
print "In while 1"
if i > 0:
break
i += 1
print "Left the 1 loop"
# Coverage.py lets the developer exclude lines that he knows will not be
# executed. So far, the branch coverage doesn't use all that information
# when deciding which lines are partially executed.
#
# Here, even though the else line is explicitly marked as never executed,
# the if line complains that it never branched to the else:
if x < 1000:
# This branch is always taken
print "x is reasonable"
else: # pragma: nocover
print "this never happens"
# try-except structures are complex branches. An except clause with a
# type is a three-way branch: there could be no exception, there could be
# a matching exception, and there could be a non-matching exception.
#
# Here we run the code twice: once with no exception, and once with a
# matching exception. The "except" line is marked as partial because we
# never executed its third case: a non-matching exception.
for y in (1, 2):
try:
if y % 2:
raise ValueError("y is odd!")
except ValueError:
print "y must have been odd"
print "done with y"
print "done with 1, 2"
# Another except clause, but this time all three cases are executed. No
# partial lines are shown:
for y in (0, 1, 2):
try:
if y % 2:
raise ValueError("y is odd!")
if y == 0:
raise Exception("zero!")
except ValueError:
print "y must have been odd"
except:
print "y is something else"
print "done with y"
print "done with 0, 1, 2"
my_function(1)
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