spis2022.github.io

SPIS, FOCS, 10.15, 0804

Testing

Using pytest with repl.it: step-by-step, with animation

• Put functions in a separate file, functions.py
• In main.py, use from functions import my_func for each function
• Create separate file tests.py with import pytest at the top
• To run the main program, just use the Run button like usual
• To run the tests, use pytest tests.py in the Shell window

Important to know:

• The first time you click Run, it may take some time for pytest to be installed
• If you try to type pytest tests.py too soon, you’ll get an error
• This is shown in the animation
• In that case, just wait (in the main Console window, for pytest to be installed)

Here’s a repl that you can “fork” to play with this code for yourself:

@phtcon/spis2022-FOCS-0804

Strong Style Pairing

Strong Style Pairing

While loops

Here is an example of rewriting the first_factor_found function using a while loop instead of a for loop

@PhillipConrad/spis2022-FOCS-0804

Some notes on while loops:

• In general, the form is while condition: on the first line, where condition is something that’s true or false.
• The first time the while loop is encountered, if the condition is false, we skip over it entirely.
• Otherwise, if the condition is true, we go through all of the code once, and then come back and start over, evaluating the condition again
• Ideally, something in the code will change the condition to eventually be false; otherwise, we will have an infinite loop, which is almost never what we want.

while condition:
   do_something()
   do_something_else()

A more specific example:

i=1;
while i<10:
  print("i=",i)
  i+=1
  

Here’s the output:

i= 1
i= 2
i= 3
i= 4
i= 5
i= 6
i= 7
i= 8
i= 9

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