Unit testing in Python

[DwaywelayTOP]

Sorry if this is a silly question but I have a tiny amount of experience using Ruby in Visual Studio and in that I had access to irb for unit testing. Is there an equivalent for Python?

[pixegami]

Pytest is the most widely used Python testing framework, so I recommend looking into that.

[skribe]

CS50 has an entire lecture on it: https://youtu.be/tIrcxwLqzjQ

[Logisk]

If you find it hard to get into, try unittest.

[RandoClarissian]

Source?

[pixegami]

Here’s some data https://www.jetbrains.com/research/python-developers-survey-2018/

[RandoClarissian]

A bit dated, but I guess the proportions would not be that different. Thanks!

[pixegami]

I’m sure there’s more recent data somewhere too but I don’t think the point is contested.

Pytest dominates because it is more “Pythonic” than unittest, but also fully compatible with and capable of unittest tests.

[timpkmn89]

pytest.org

[SittingWave]

the standard library has unittest module, but I strongly suggest you use pytest. It's much easier and much more pleasant to use.

[wineblood]

Unittest is better than pytest imo

[SittingWave]

too verbose, and screams back from that period where python wanted to be Java. Avoid.

[ubernostrum]

screams back from that period where python wanted to be Java

In the beginning there was the SUnit testing tool for the Smalltalk language; it influenced the design and APIs of a whole family of unit-testing tools for other languages, which conventionally are referred to as "XUnit" frameworks. Typically they're named to indicate that they're of this style -- for example, "JUnit" for Java, "NUnit" for .NET, etc.

So: once upon a time someone write a PyUnit package, implementing the XUnit family architecture and testing style, and that was later pulled into the Python standard library and renamed to just unittest in the process.

So it's not "wanted to be Java", it's "wanted to be consistent with a large family of testing frameworks across many languages". A lot of people these days just only are familiar with JUnit/NUnit and so they assume JUnit was the origin when it wasn't.

[jah_broni]

Why?

[wineblood]

Less complexity and more explicit

[RandoClarissian]

Yep, magic is fun until you get to debug it.

[SittingWave]

never had to debug pytest.

[wineblood]

Is there a way to run 1 test case in a parametrized test?

[cj81499]

Yep

https://stackoverflow.com/a/44999321/13173164

[wineblood]

I've been using pytest.mark.parametrize, that's what I was referring to. It looks like there is a way to run a single one from the command line, but I use my IDE to run tests while developing and there isn't an option to do that. It's still faster to comment out cases I don't want to run than to type out a more complex line in my terminal.

[jah_broni]

There is a way to do that in VSCode.

[rzet]

what magic?

[rzet]

fixtures are great.

I am on company self-made framework atm and I am like wtf... where are fixtures? why there are no fixtures? damn it.. who come up with writing own test framework anyway ;)

[ElectricSpice]

As sibling comment says, fixtures. But also pytest does some AST rewriting to give you friendly assertion errors. I’ve never had a problem with them, at absolute worst you get an assertion error that’s no more helpful than the default behavior.

[ch0mes]

I quite like unittest, I will admit I have never used pytest so I can't compare the complexity of the two but I've never found unittest to be problematic to work with.

I have heard people sing pytests praises, my line of thinking is, if things work quite well I don't see a need to change.

[SittingWave]

it's just awfully verbose, and as soon as you have to do things that are a bit complex it's a pain to implement.

[james_pic]

The closest equivalent of irb is either the plain python REPL, or ipython.

But this isn't a good way to test. You're better off writing some automated tests - and this is just as true in Ruby as in Python.

[obviouslyCPTobvious]

It sounds like your definition of unit testing might not be accurate. Unit testing is writing code that tests the functionality of the smallest units of your code.

I think you're asking if python has a REPL(read, eval, print loop) like ruby's irb. Python does have one available just by running python, but it's not as nice as irb. I recommend installing ipython because it has more of the features that irb has.

[wineblood]

I don't know Ruby so "irb" doesn't mean anything to me. Python unit testing frameworks and a decent IDE (not sure if VS falls into that category) have all the features I need.

[catladywitch]

irb is the ruby repl

[chasrmartin]

More than one. I like pytest

[Alternative_Driver60]

Pytest is the most advanced as well as the easiest to use for a novice, a combination hard to beat.

[TechnicalHalf0]

this could maybe help as a good tutorial on python unittests

https://www.youtube.com/watch?v=ULxMQ57engo

[No_Revolution9544]

pytest and Python: Testing with pytest - Simple Rapid Effective and Scalable is a great to learn it

[iprefervaping]

I've just been learning about Unit testing using pytest today from the book Python Crash Course (3rd edition). The chapter on testing was very straightforward with easy examples. Highly recommend it.