Adds Module 6: Testing Code #125

rsokl · 2019-12-21T19:55:53Z

@davidmascharka (and anyone else!) I am in the process of completing an early draft of Module 6. I will make note of the sections that are ready for review/edits below. Thank you for your help!

I have pushed a temporary branch that has the updated html for this WIP - so that you can read the content as it would appear on the website. The branch is here. You can clone/download it and view index.html in your browser to get to the PLYMI home page.

Ready for Review

module6.rst
Intro_to_Testing.md
Pytest.md
Hypothesis.md

Co-Authored-By: David Mascharka <davidmascharka@users.noreply.github.com>

rsokl · 2020-03-30T18:56:42Z

Thanks so much for the careful read through @davidmascharka ! Hugely appreciated

Python/Module6_Testing/Hypothesis_Practice_Exercises.md

Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

Zac-HD

(quick partial review)

Python/Module5_OddsAndEnds/Modules_and_Packages.md

Python/Module6_Testing/Hypothesis.md

Python/Module6_Testing/Hypothesis_Practice_Exercises.md

…testing-code

Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

…testing-code

Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

…testing-code

Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

…testing-code

Zac-HD

🎉

Zac-HD · 2022-08-27T23:35:59Z

Python/Module6_Testing/Pytest.md

+)
+```
+
+This setup file dictates that a user must have Python 3.6+ installed - we will bar Python 3.5 and below so that we are free to make use of [f-strings](https://www.pythonlikeyoumeanit.com/Module2_EssentialsOfPython/Basic_Objects.html#Formatting-strings) in our code, which were introduced in Python 3.6. Additionally, we will require pytest and hypothesis for running tests; the Hypothesis library will be introduced in a later section.


It's been a while I guess, but Python 3.6 is now past end-of-life and so you could just point to https://devguide.python.org/versions/ with a strong recommendation to avoid unsupported versions, and ideally stick to versions for which bugfixes are being issued (i.e. only support older if you're publishing code for others to use, and they can't feasibly update their Python).

Zac-HD · 2022-08-27T23:38:40Z

Python/Module6_Testing/Pytest.md

+----> 1 assert count_vowels("aA bB yY", include_y=True) == 4
+
+AssertionError: assert 2 == 4
+ +  where 2 = <function count_vowels at 0x000001B91B913708>('aA bB yY', include_y=True


Suggested change

+ where 2 = <function count_vowels at 0x000001B91B913708>('aA bB yY', include_y=True

+ where 2 = <function count_vowels at 0x000001B91B913708>('aA bB yY', include_y=True)

Zac-HD · 2022-08-27T23:54:21Z

Python/Module6_Testing/Hypothesis.md

+It is often the case that the process of *describing our data* is by far the heaviest burden that we must bear when writing tests. This process of assessing "what variety of values should I test?", "have I thought of all the important edge-cases?", and "how much is 'enough'?" will crop up with nearly every test that we write.
+Indeed, these are questions that you may have been asking yourself when writing `test_count_vowels_basic` and `test_merge_max_mappings` in the previous sections of this module.
+
+[Hypothesis](https://hypothesis.readthedocs.io/) is a powerful Python library that empowers us to write a _description_ (specification, to be more precise) of the data that we want to use to exercise our test.


I don't think there's a clear distinction between description and specification here, so I'd just delete the parenthetical.

Zac-HD · 2022-08-27T23:58:35Z

Python/Module6_Testing/Hypothesis.md

+
+Hypothesis' [given decorator](https://hypothesis.readthedocs.io/en/latest/details.html#the-gory-details-of-given-parameters) is responsible for:
+
+ - drawing values from Hypothesis' so-called "strategies" for describing input data for our test function


Suggested change

- drawing values from Hypothesis' so-called "strategies" for describing input data for our test function

- drawing values from Hypothesis' "strategies" for describing input data for our test function

"so-called" has two possible meanings - either to to introduce a new word or phrase, or that the following description is unsuitable or incorrect. Apparently the first is more common in the US but the latter in Commonwealth countries, so to avoid ambiguity I'd just drop it.

Zac-HD · 2022-08-27T23:59:00Z

Python/Module6_Testing/Hypothesis.md

+
+
+Let's see the `given` decorator in action by writing a simple "test" for which `x` should be integers between 0 and 10, and `y` should be integers between 20 and 30.
+To do this we will make use of the `integers` Hypothesis strategy.


Suggested change

To do this we will make use of the `integers` Hypothesis strategy.

To do this we will make use of the `st.integers()` Hypothesis strategy.

Zac-HD · 2022-08-28T00:08:11Z

Python/Module6_Testing/Hypothesis.md

+<!-- #region -->
+**Exploring other Core Strategies: Solution**
+
+Dictionaries of arbitrary size whose keys are positive-values integers and whose values are `True` or `False.


Suggested change

Dictionaries of arbitrary size whose keys are positive-values integers and whose values are `True` or `False.

Dictionaries of arbitrary size whose keys are positive-values integers and whose values are `True` or `False`.

Zac-HD · 2022-08-28T00:10:17Z

Python/Module6_Testing/Hypothesis.md

+    # We need to shuffle the ordering of our characters so that
+    # our input string isn't unnaturally patterned; e.g. always 
+    # have its vowels at the end
+    shuffle(letters)
+    in_string = "".join(letters)


Trouble! Hypothesis will seed the random-number generator, so you shouldn't show using random functions in PBTs.

Or, preferably, use the st.random() strategy to provide a Random instance that you use to do the shuffle, and explain why that's a good idea.

Zac-HD · 2022-08-28T00:11:29Z

Python/Module6_Testing/Hypothesis.md

+# This is only one of many ways that you could have created this
+# strategy
+cat_or_dog = st.booleans().map(lambda x: "cat" if x else "dog")


I'd prefer to show st.sampled_from(["cat", "dog"]) as the primary example, with the remapped booleans as a curiosity.

Zac-HD · 2022-08-28T00:15:44Z

Python/Module6_Testing/Hypothesis_Practice_Exercises.md

+```
+
+The value doesn't change at all because we would have to exceed 64-bits allotted to represent a floating point number.
+Thus `x < x + 1` fails to hold for `x = 2.0 ** 53`. 


Suggested change

Thus `x < x + 1` fails to hold for `x = 2.0 ** 53`.

Thus `x < x + 1` fails to hold when `2.0 ** 53 <= x < inf`.

Zac-HD · 2022-08-28T00:18:21Z

Python/Module6_Testing/Hypothesis_Practice_Exercises.md

+**Describing objects that evaluate to `False`**
+
+```python
+falsies = st.sampled_from([False, 0, 0.0, "", [], tuple(), {}])


Suggested change

falsies = st.sampled_from([False, 0, 0.0, "", [], tuple(), {}])

falsies = st.sampled_from([False, 0, 0.0, "", [], (), {}])

I'd also add a comment explicitly noting that the same objects will be generated every time, so this strategy is unsafe if you mutate them. Instead, you could rely on the fact that calling the respective type objects with no arguments returns the empty/falsy value: st.sampled_from([bool, int, float, str, list, tuple, dict]).map(lambda type_: type_()).

rsokl added 30 commits December 7, 2019 17:23

Begin section on testing code

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work on intro

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complete first cut of intro

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working on motivation

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work on motivation

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continue developing motivation

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complete draft of motivations

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fix inconsistency in count_vowels docstring

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fix inconsistency in count_vowels docstring

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fix inconsistency between docstring and type-hint

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add first example

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discuss asserts

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minor wording changes

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Merge branch 'master' into testing-code

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minor formatting fix: italicized was broken

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finish section on count-vowels test

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touch up working in first couple of sections

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complete section on assertions

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add test suite to package structure

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use consistent voice in testing tests

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rearrange mateirals: testing tests goes before assertions

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move testing-code material to its own module

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fix rst delimiter length mismatch for module 5

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introduce merge-max-mappings

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adding summary to basic test structure

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add test example for merge-max-dicts

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Finish intro to testing

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add initial pytest section

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remove ipynb pairing

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rsokl and others added 2 commits March 30, 2020 14:48

Update Python/Module6_Testing/Hypothesis.md

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Co-Authored-By: David Mascharka <davidmascharka@users.noreply.github.com>

Update Python/Module6_Testing/Hypothesis.md

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Co-Authored-By: David Mascharka <davidmascharka@users.noreply.github.com>

rsokl added 3 commits April 4, 2020 16:29

add hypothesis practice exercises

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add beginning of Writing Your Own Strategies

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Merge branch 'master' into testing-code

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Zac-HD reviewed Feb 11, 2021

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rsokl and others added 8 commits February 11, 2021 19:35

Update Python/Module6_Testing/Hypothesis_Practice_Exercises.md

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Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

fix merge conflicts

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fix header level

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fix kernel info

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Reformat decorator aside and fix clunky wording

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Introduction to Testing -> The Basics of Writing Tests for Python Code

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Add hypothesis practice exercises

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Zac-HD reviewed Aug 21, 2022

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rsokl and others added 13 commits August 22, 2022 19:47

Merge branch 'testing-code' of github.com:rsokl/Learning_Python into …

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…testing-code

remove distutils ref

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Apply suggestions from code review

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Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

Merge branch 'testing-code' of github.com:rsokl/Learning_Python into …

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…testing-code

Ease up on discussion of len esge case

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Update Python/Module6_Testing/Hypothesis.md

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Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

Update Python/Module6_Testing/Hypothesis.md

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be more precise in description of st.text()

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Update Python/Module6_Testing/Hypothesis.md

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Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

Fix description of lambda, and make use of term 'strategy' consistent

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Adds Module 6: Testing Code #125

Adds Module 6: Testing Code #125

rsokl commented Dec 21, 2019 •

edited

rsokl commented Mar 30, 2020

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	+ where 2 = <function count_vowels at 0x000001B91B913708>('aA bB yY', include_y=True
	+ where 2 = <function count_vowels at 0x000001B91B913708>('aA bB yY', include_y=True)


		Hypothesis' [given decorator](https://hypothesis.readthedocs.io/en/latest/details.html#the-gory-details-of-given-parameters) is responsible for:

		- drawing values from Hypothesis' so-called "strategies" for describing input data for our test function

	- drawing values from Hypothesis' so-called "strategies" for describing input data for our test function
	- drawing values from Hypothesis' "strategies" for describing input data for our test function



		Let's see the `given` decorator in action by writing a simple "test" for which `x` should be integers between 0 and 10, and `y` should be integers between 20 and 30.
		To do this we will make use of the `integers` Hypothesis strategy.

	To do this we will make use of the `integers` Hypothesis strategy.
	To do this we will make use of the `st.integers()` Hypothesis strategy.

	Dictionaries of arbitrary size whose keys are positive-values integers and whose values are `True` or `False.
	Dictionaries of arbitrary size whose keys are positive-values integers and whose values are `True` or `False`.

	Thus `x < x + 1` fails to hold for `x = 2.0 ** 53`.
	Thus `x < x + 1` fails to hold when `2.0 ** 53 <= x < inf`.

	falsies = st.sampled_from([False, 0, 0.0, "", [], tuple(), {}])
	falsies = st.sampled_from([False, 0, 0.0, "", [], (), {}])

Adds Module 6: Testing Code #125

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rsokl commented Dec 21, 2019 • edited

Ready for Review

rsokl commented Mar 30, 2020

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rsokl commented Dec 21, 2019 •

edited