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# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
# 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 bytecode 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 developers exclude lines that they know 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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