173 lines
4.7 KiB
Markdown
173 lines
4.7 KiB
Markdown
# Chapter 11. Testing Your Code
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Learn how to test code using Python's `unittest` module.
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## Testing a Function
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Function to be tested as shown below.
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```python
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def get_formatted_name(first, last):
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"""Generate a neatly formatted full name."""
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full_name = f"{first} {last}"
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return full_name.title()
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```
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A script that should use `get_formatted_name`
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```python
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from name_function import get_formatted_name
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print("Enter 'q' at any time to quit.")
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while True:
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first = input("\nPlease give me a first name: ")
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if first == 'q':
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break
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last = input("Please give me a last name: ")
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if last == 'q':
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break
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formatted_name = get_formatted_name(first, last)
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print(f"\tNeatly formatted name: {formatted_name}.")
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```
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To make sure `get_formatted_name` function properly, using `unittest` module of Python
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```python
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import unittest
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from name_function import get_formatted_name
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class NamesTestCase(unittest.TestCase):
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"""Test for name_function.py"""
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def test_first_last_name(self):
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"""Do names like 'Janis Joplin' work?"""
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formatted_name = get_formatted_name('janis', 'joplin')
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self.assertEqual(formatted_name, 'Janis Joplin')
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if __name__ == '__main__':
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unittest.main()
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```
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Key points:
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* Import `unittest` module as shown
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* Import function to be tested
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* Here, `unittest`'s most useful feature `assert` is used. `assertEqual` can compare two objects
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* `__name__` is a **special variable**, which is set when the program is executed. If the file is being run as the main program, the value of `__name__` is set to `'__main__'`
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Result of running this test:
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```
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.
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----------------------------------------------------------------------
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Ran 1 test in 0.000s
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OK
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```
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* First dot represent the single test passed.
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### A Failing Test
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Failure case returns
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```
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F
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======================================================================
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FAIL: test_first_last_name (__main__.NamesTestCase)
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Do names like 'Janis Joplin' work?
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----------------------------------------------------------------------
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Traceback (most recent call last):
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File "test_name_function.py", line 10, in test_first_last_name
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self.assertEqual(formatted_name, 'Janis Joplins')
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AssertionError: 'Janis Joplin' != 'Janis Joplins'
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- Janis Joplin
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+ Janis Joplins
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? +
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----------------------------------------------------------------------
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Ran 1 test in 0.001s
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FAILED (failures=1)
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```
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Highlight:
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* `FAIL: test_first_last_name` tell's where the error coming from.
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## Fix them
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If employing TDD, we can first create test case, then develop code to be test against.
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## Testing a Class
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e.g. above shown how to write test case for single function, we also need to write test for class.
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### A Variety of Assert Methods
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Python `unittest` module provide various assert methods in `unittest.TestCase` class.
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List of available assert methods
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| Method | Use |
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| ------------------------- | -------------------------------- |
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| `assertEqual(a,b)` | Verify `a == b` |
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| `assertNotEqual(a,b)` | Verify that `a != b` |
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| `assertTrue(x)` | Verify that x is True |
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| `assertFalse(x)` | Verify that x is False |
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| `assertIn(item, list)` | Verify that item is in list |
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| `assertNotIn(item, list)` | Verrify that item is not in list |
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### A Class to Test
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* class to be tested in *survey.py* have class `AnonymousSurvey`
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```python
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class AnonymousSurvey:
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"""Collect anonymous answers to a survey questions"""
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def __init__(self, question):
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"""Store a question, and prepare to store response."""
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self.question = question
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self.responses = []
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def show_question(self):
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"""Show the survey question"""
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print(self.question)
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def store_response(self, new_response):
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"""Store a single response to the survey"""
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self.responses.append(new_response)
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def show_results(self):
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"""Show all the responses that have been given"""
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print("Survey results:")
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for response in self.responses:
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print(f"- {response}")
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```
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* script to use `AnonymousSurvey` *language_survey.py*
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```python
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from survey import AnonymousSurvey
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# Define a question, and make a survey.
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question = "What language did you first learn to speak?"
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my_survey = AnonymousSurvey(question)
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# Show the questions, and store responses to the question
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my_survey.show_question()
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print("Enter 'q' at any time to quit.\n")
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while True:
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response = input("Language: ")
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if response == 'q':
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break
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my_survey.store_response(response)
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# Show the survey results
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print("\nThank you to everyone who participate in the survey")
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my_survey.show_results()
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```
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If we want to |