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I want to use unittest in python to check if a method returns object of the right class.
Every example in the web shows tests for 'type' returned.
For example, to check for <type 'list'> or <type 'type'> , we could use:
self.assertIsInstance(result, list)
self.assertIsInstance(result[0], tuple)
What I am looking for is an example to check for <class'sqlalchemy.orm.query.Query'>
Would appreciate any help. Thankyou.
543
assertIsInstance() in Python is a unittest library function that is used in unit testing to check whether an object is an instance of a given class or not. This function will take three parameters as input and return a boolean value depending upon the assert condition.
Using isinstance() function, we can test whether an object/variable is an instance of the specified type or class such as int or list. In the case of inheritance, we can checks if the specified class is the parent class of an object. For example, isinstance(x, int) to check if x is an instance of a class int .
The command to run the tests is python -m unittest filename.py . In our case, the command to run the tests is python -m unittest test_utils.py .
First you need to create a test file. Then import the unittest module, define the testing class that inherits from unittest. TestCase, and lastly, write a series of methods to test all the cases of your function's behavior. First, you need to import a unittest and the function you want to test, formatted_name() .
You could use assertIsInstance(), presumably using isinstance() which is the recommended function for testing types. You could also assertIs() or assertTrue() combined with type() depending on the context:
#assert.py
import unittest
class TestType(unittest.TestCase):
def setUp(self):
self.number = 1
def test_assert_true(self):
self.assertTrue(type(self.number) is int)
def test_assert_is_instance(self):
self.assertIsInstance(self.number, int)
def test_assert_is_with_type(self):
self.assertIs(type(self.number), int)
def test_assert_is(self):
self.assertIs(self.number, int)
if __name__ == '__main__':
unittest.main()
$ python assert.py
test_assert_is (__main__.TestType) ... FAIL
test_assert_is_instance (__main__.TestType) ... ok
test_assert_is_with_type (__main__.TestType) ... ok
test_assert_true (__main__.TestType) ... ok
======================================================================
FAIL: test_assert_is (__main__.TestType)
----------------------------------------------------------------------
Traceback (most recent call last):
File "assert.py", line 19, in test_assert_is
self.assertIs(self.number, int)
AssertionError: 1 is not <type 'int'>
----------------------------------------------------------------------
Ran 4 tests in 0.000s
FAILED (failures=1)
The assertion error of the test_assert_is(self) might lead one to believe the type of 1 is not integer however it's comparing the object represented by 1 and the object that describes the type of an integer. This is most likely why isinstance() is preferred since it's more verbose about what it's checking and less typing is involved, so in general less error prone.
83
This should work:
self.assertIsInstance(result, sqlalchemy.orm.query.Query)
You need to have import sqlalchemy in the file.
41
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