CODEWITHSUNDEEP
pythonunit-testingmocking
miphos
miphos

Reputation: 81

Mock a property of a string

What I'm trying to accomplish is to mock a the split inside a method like this

def method_separator(s):
    try:
        a, b, c = s.split('-')
        print a, b, c
    except: ValueError:
        print "An error occurred or so"

In the test

with self.assertRaises(ValueError):
    with mock.patch(What to put here?) as mock_patch:
    mock_patch.return_value = "TEXT" # To raise ValueError
    this = method_separator('Some-good-text') # The mock should not let this good test to pass

I've made the mock working with string.split 

def method_separator(s):
    try:
        a, b, c = split.string(s, '-')
        print a, b, c
    except: ValueError:
        print "An error occurred or so"

with self.assertRaises(ValueError):
    with mock.patch('string.split') as mock_patch:
    mock_patch.return_value = "TEXT" # To raise ValueError
    this = method_separator('Some-good-text') # The mock should not let this good test to pass

Even if that work, the question remains, it is posible to do? mock the result of "".split('-')

Upvotes: 1

Views: 6465

Answers (1)

lortimer
lortimer

Reputation: 710

The string you want to split is passed into your method. You don't need to use patch, just pass a Mock into the method.

# Production Code
def method_separator(s):
try:
    a, b, c = s.split('-')
    print a, b, c
except: ValueError:
    print "An error occurred or so"

# Test Code
from unittest.mock import Mock

with self.assertRaises(ValueError):
    mock_string = Mock(spec=string)
    mock_string.side_effect = ValueError("Some message")
    this = method_separator(mock_string)

patch is useful when you want your production to get a mock through an import statement. If you pass values directly to your production code, you have to make your own Mock objects.

Upvotes: 1

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