PYTHON setup.py build_ext --inplace
PYTHON test_profile.py

######## setup.py ###########

from distutils.extension import Extension
from distutils.core import setup
from Cython.Build import cythonize

from Cython.Compiler.Options import directive_defaults
directive_defaults['linetrace'] = True
directive_defaults['binding'] = True

extensions = [
    Extension("collatz", ["collatz.pyx"], define_macros=[('CYTHON_TRACE', '1')])
]

setup(
    ext_modules = cythonize(extensions)
)

######## test_profile.py ###########

from collatz import collatz

try:
    import line_profiler
except ImportError:
    print("No line profiler, skipping test.")
    import sys
    sys.exit(0)

profile = line_profiler.LineProfiler(collatz)
profile.runcall(collatz, 19)
profile.print_stats()

stats = profile.get_stats()
assert len(stats.timings) > 0, "No profile stats."
for key, timings in stats.timings.items():
    if key[-1] == 'collatz':
        assert len(timings) > 0
        break
else:
    raise ValueError("No stats for collatz.")

######## collatz.pyx ###########

def collatz(n):
    while n > 1:
        if n % 2 == 0:
            n //= 2
        else:
            n = 3*n+1
