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Python: how to create a positive test for procedures?

I have a class with some #staticmethod's that are procedures, thus they do not return anything / their return type is None.
If they fail during their execution, they throw an Exception.
I want to unittest this class, but I am struggling with designing positive tests.
For negative tests this task is easy:
assertRaises(ValueError, my_static_method(*args))
assertRaises(MyCustomException, my_static_method(*args))
...but how do I create positive tests? Should I redesign my procedures to always return True after execution, so that I can use assertTrue on them?

Without seeing the actual code it is hard to guess, however I will make some assumptions:
The logic in the static methods is deterministic.
After doing some calculation on the input value there is a result
and some operation is done with this result.
python3.4 (mock has evolved and moved over the last few versions)
In order to test code one has to check that at least in the end it produces the expected results. If there is no return value then the result is usually stored or send somewhere. In this case we can check that the method that stores or sends the result is called with the expected arguments.
This can be done with the tools available in the mock package that has become part of the unittest package.
e.g. the following static method in my_package/my_module.py:
import uuid
class MyClass:
#staticmethod
def my_procedure(value):
if isinstance(value, str):
prefix = 'string'
else:
prefix = 'other'
with open('/tmp/%s_%s' % (prefix, uuid.uuid4()), 'w') as f:
f.write(value)
In the unit test I will check the following:
open has been called.
The expected file name has been calculated.
openhas been called in write mode.
The write() method of the file handle has been called with the expected argument.
Unittest:
import unittest
from unittest.mock import patch
from my_package.my_module import MyClass
class MyClassTest(unittest.TestCase):
#patch('my_package.my_module.open', create=True)
def test_my_procedure(self, open_mock):
write_mock = open_mock.return_value.write
MyClass.my_procedure('test')
self.assertTrue(open_mock.call_count, 1)
file_name, mode = open_mock.call_args[0]
self.assertTrue(file_name.startswith('/tmp/string_'))
self.assertEqual(mode, 'w')
self.assertTrue(write_mock.called_once_with('test'))

If your methods do something, then I'm sure there should be a logic there. Let's consider this dummy example:
cool = None
def my_static_method(something):
try:
cool = int(something)
except ValueError:
# logs here
for negative test we have:
assertRaises(ValueError, my_static_method(*args))
and for possitive test we can check cool:
assertIsNotNone(cool)
So you're checking if invoking my_static_method affects on cool.

Initializing a Python object

I am trying to teach myself object oriented programming in Python with the book "Python 3, Object Oriented Programming", by Dusty Phillips. On pages 54 and 55 he creates a class called Note and encourages the reader to repeat the example and import the module from the interpreter with the following commands. However, when I do, I type the n1 = command I get the message from the interpreter "TypeError: object() takes no parameters. Am I missing something in the implementation of this object, or did the book give a faulty example? Mind you the example and the lines typed into the interpreter are taken exactly from the book, at least I think I made no errors in copying the lines. This is different initialization syntax than C++, which makes me wonder if the author gave a bad example, but in the book example it looks as if he is trying to initialize with a call to the object directly and the object is supposed to recognize the text that gets passed to memo. Also I tried to run the example in python 2.7.9 and 3.4.2 to see if this was a version issue.
Interpreter lines
from notebook import Note
n1 = Note("hello first") # the code execution gets stopped here fur to the error
n2 = Note("hello again")
n1.id
n2.id
import datetime
# store the next available id for all new notes
last_id = 0
class Note:
'''Represent a note in the notebook. Match against a
string in searches and store tags for each note.'''
def _init_(self, memo, tags=''):
'''initialize a note with memo and optional
space-seperated tags. Automatically set the note's
creation date and a unique id.'''
self.memo = memo
self.tags = tags
self.creation_date = datetime.date()
global last_id
last_id += 1
self.id = last_id
def match(self, filter):
'''Determine if this note matches the filter
text. Return True if it matches, False otherwise.
Search is case sensitive and matches both text and
tags'''
return filter in self.memo or filter in self.tags

Maybe do what Christian said: Use __init__ instead of _init_. You need to have double underscores not single underscores. You can look at the Python Docs.

You are missing double underscores in the special __init__ method. You only have single underscores.
You might also consider having Note explicitly inherit from object, i.e. class Note(object).

How to change class object parameters from another module (python)

So I've searched around and couldn't find an answer. I'm looking to change parameters from an object created in my main file, in a module. For example, I'm testing this with a simple piece of code here:
-this is my main file, from which i create the objects and define some properties
import class_test_2
class dog():
name=''
spots=0
def add_spots(self):
self.spots+=1
def main():
fido=dog()
fido.name='Fido'
print('Fido\'s spots: ',fido.spots)
fido.add_spots()
print('Fido\'s spots: ',fido.spots)
class_test_2.class_test()
print('Fido\'s spots: ',fido.spots)
if __name__=='__main__':
main()
-this is the module, from which I want to use functions to change the attributes in the main file
from class_test_1 import dog
def class_test():
fido.add_spots()
-So my question is how can I do this/why doesn't this piece of code above work?
Running the main function on its own shows fido's spots increasing by 1 each time its printed. Running the code calling the module however gives a NameError so my module isn't recognising the class exists even though I've managed to import it. Thanks in advance for any help.

Your variable "fido" is only defined within your "main" function. You must provide your "class_test" function with the variable.
For example:
class_test_2.class_test(fido)
Then your class_test function gets an argument. You can choose the name freely. I used the_dog in the example:
def class_test(the_dog):
the_dog.add_spots()
In this case the_dog points to the same instance of your dog class as fido.

Python my Class throws TypeError

here is my code.
import fileinput, random
from os import system as sys
from sys import exit
class crazy8(object):
question = raw_input("please enter a yes or no question \n")
def fortune(self, filex, current):
current = r"./"
fortunes = list(fileinput.input(filex))
sys("cd", current)
print random.choice(fortunes)
crazy8.fortune(r"./crazy8")
exit(0)
When I run the program, I enter a question (I know that the program does not care what is entered). I think I did something wrong with the class. I know it works fine when there is no class: statement, but I need the class there (after I am done, I am going to use this as a module).
After the question, I get
TypeError: unbound method fortune() must be called with crazy8 instance as first argument (got str instance instead)
(I did not add any error checking yet. I will try to add try and catch/raise for if the file ./crazy8 does not exist. Also, I am later going to add a file that will automatically sys("touch ./crazy8") (on Mac/linux) and, after I find out how to create a file on Windows, I will add that.

You need to create and instance or object of the class(same thing).
x = crazy8()
x.fortuner(r,"./crazy8")
It's also considered common practice to have your classes start with capital letters and instances with lowercase.
class Crazy8
crazy8 = Crazy8()
Hope this helps

Either you should create an instance of the class and call its method, or you should make the method static.
Please refer to:
Static methods in Python

Python: Calling module's functions from within a class

I have the following code:
from suchandsuch import bot
class LaLaLa():
def __init__(self):
self.donenow = 0
print "LaLaLa() initialized."
return
def start(self):
pages = bot.cats_recursive('something')
for page in pages:
self.process_page(page)
When I try to run y = LaLaLa() and then y.start(), though, I get an error:
AttributeError: LaLaLa instance has no attribute 'cats_recursive'
This makes me suspect that Python is trying to call cats_recursive() not from suchandsuch's bot sub-module (as is defined at the beginning of the file), but rather from LaLaLa(), which of course doesn't have the cats_recursive() function. Is there a way to force a class instance to use an imported module, rather than just look inside itself?

Posters are correct that there is nothing wrong with the code you have posted.
It's the code you didn't post that is probably the problem. It is hinted at in your naming of cats_recursive. You haven't shown us that perhaps LaLaLa is defined in or imported into bot.py.
One way to replicate your error is:
# in suchandsuch/bot.py
class LaLaLa():
def __init__(self):
self.donenow = 0
print "LaLaLa() initialized."
# don't need a `return` here
def start(self):
pages = bot.cats_recursive('something')
for page in pages:
self.process_page(page)
bot = LaLaLa()
That's just one. Another is to have __init__.py in such and such something like:
bot = LaLaLa()
Like I said, the error is in your code structure.
print the id of the bot inside LaLaLa or captrue the error with pydb and I suspect you will see that bot is an instance of LaLaLa other than y (again check the id's)

You are doing fine. Most probably there is no cats_recursive() attribute in your module for real. Check syntax, check module content.

You might find the easiest way to do this would be to try to assign the cats_recursive() to the pages variable outside the class and then pass the variable to the start() function as a parameter. If this works then keep it that way, if it doesn't work then there's probably something wrong with the code elsewhere.