Mocking Subproces Calls in Python

Question

I am trying to use mock.patch decorator in the mock library but am having problems. I have this init function where I make two subprocess calls. The first time in self.setPackageQuota() and the second time in self.setBandwidthLimit() .

class User():
    def __init__(self, username, plan, domain, owner, diskQuota, diskUsed):
        self.setUsername(username)
        self.setPlan(plan)
        self.setDomain(domain)
        self.setOwner(owner)
        self.setDiskQuota(diskQuota)
        self.setDiskUsed(diskUsed)
        self.setPackageQuota()
        self.setBandwidthLimit()

self.setPackageQuota()

def setBandwidthLimit(self):
    whmapicall   = subprocess.Popen(["whmapi1" , "showbw", 'searchtype=user', 'search=^%s$' % self.username], stdout=subprocess.PIPE)
    whmapireturn = whmapicall.stdout.read().split("\n")
    for line in whmapireturn:

self.setPackageQuota()

def setPackageQuota(self):
    whmapicall   = subprocess.Popen(["whmapi1" , "getpkginfo", "pkg=%s" % self.plan], stdout=subprocess.PIPE)
    whmapireturn = whmapicall.stdout.read().split("\n")
    for line in whmapireturn:

I would much rather patch whmapireturn to be something else. I also would not like to not run subprocess.Popen . My inital thought was to patch out @mock.patch('subprocess.Popen', MockedClass) and @mock.patch('whmapireturn', OtherMockedClass) but I cant seem to get it to work. How would I test an init fucntion like this while patching out things that I can't have in my enviroment? Thanks in advance for any asistance.

Answer 1

I comprehend from your question that you want to mock-patch the Subprocess.Popen() call from your file. For that you should use the following approach:-

Let take the scenario where your file name is for which you want to create the unittest. Therefore:- in the unittest file, you should write:-

import library

@mock.patch("library.subprocess")
def test_subprocess_call(mock_subprocess):
    mock_subprocess.Popen.return_value = None

I hope you find your answer.