In this exercise, you will be given a few lines of code that perform a certain task (that you will have to understand) and then write an automated test that checks whether that task is performed correctly.

Step 0

If you haven't already, fork this repository and clone it on your computer, and use uv to create a new environment for it (with pytest):

uv init
uv add --dev pytest

Tip

You can find useful information on the following chapters of our notes on Testing basics, The Fields of Saskatchewan and Test frameworks.

Step 1: Understanding the existing code

• Spend some time reading the code, try to run it and see whether you understand what's going on.
• Have you seen datetime before?
• Play using your favourite tool (notebook, terminal, scripts) with the functions and objects used in times.py.

Tip

Imagine we have two instruments. The first one takes measurements for 5 minutes, stops for 1, and takes measurements again for another 5 minutes. The other one measures for 1 minute, and has a gap of 2 minutes between intervals. If we start our measurments with the first one at t=0 and the second one starts at t=2, then we would have a pattern of observations like:

block-beta
  columns 13
  a["obs 1 [5min]"]:5 space:1 c["obs 1 [5min]"]:5 space:2
  space:2 d["obs 2 [1min]"]:1 space:2 e["obs 2 [1min]"]:1 space:2 f["obs 2 [1min]"]:1 space:2 g["obs 2 [1min]"]:1 space:1
  h["00:00"]:1 j["01:00"]:1 k["02:00"]:1 l["03:00"]:1 m["04:00"]:1 n["05:00"]:1 o["06:00"]:1 p["07:00"]:1 q["08:00"]:1 r["09:00"]:1 s["10:00"]:1 t["11:00"]:1 u["12:00"]:1

Loading

The time_range function generates the observation blocks for a given start and end time, a number of intervals and a duration for the gaps. For the first row above, this would be: "2025-01-01 00:00:00", "2025-01-01 00:11:00", 2, 60 and for the second: "2025-01-01 00:02:00", "2025-01-01 00:12:00", 4, 120.
And the compute_overlap_time should provide:

[('2025-01-01 00:02:00', '2025-01-01 00:03:00'),  # first interval
 ('2025-01-01 00:08:00', '2025-01-01 00:09:00')]  # second interval 

Step 2: Writing a unit test

• Create a new file called test_times.py in the same directory where times.py is.
• Make the overlap_time function accessible to that file. (Hint: You need to import the file).
• Move the content from the if __name__ ... block from times.py to a function called test_given_input into test_times.py and fill the gaps for result and expected. (For now, you can copy the output of the program as the expected value, as if being a regression test)

def test_given_input():
    ... 
    result = ... 
    expected = ...
    assert result == expected

Step 3: Running the tests

• run pytest on that directory and see whether the test is picked up by pytest and whether it passes. If the test doesn't pass, see if you can find what is going wrong.

Note

If you have created the environment using uv and installed pytest with it then you need to run uv run pytest or use the VS Code testing menu.

Step 4: Push to GitHub

• When you are happy with your solution (or want some feedback!):
  • Push your new code to your own fork.
  • On GitHub, open a pull request from your fork to the original repository.
  • In the description, include the text as required in the issue for this exercise. This will link your PR to this issue.
  • On the PR text, comment on what you found difficult or interesting, or something you learned.
• Continue with the remaining steps (7. - 9.) on the following issue in the Classwork repository.