Add `split-second-stopwatch` exercise #2547

ErikSchierboom · 2025-03-26T07:27:41Z

This PR is intended as a starting point for a discussion on adding a new practice exercise.
The exercise's goal is to have students work with time, as well as deal with a sort of state machine.

The things I'd like to discuss are:

A nice background story
Ideas on how to best structure/formulate the instructions
Thoughts on how I've setup the canonical data (it's inspired by the canonical data of circular-buffer)

I've done a basic implementation of the exercise in C#: exercism/csharp#2403

ErikSchierboom · 2025-03-28T07:07:02Z

CC @exercism/reviewers

tasxatzial

I've reviewed the instructions and intro as thoroughly as I could. Here are the changes I believe would improve clarity and flow. Hopefully, I haven't overlooked anything. Of course, there's some subjectivity involved, so feel free to adjust and incorporate whatever you find appropriate.

exercises/split-second-stopwatch/instructions.md

exercises/split-second-stopwatch/introduction.md

Co-authored-by: Anastasios Chatzialexiou <16361161+tasxatzial@users.noreply.github.com>

BNAndras · 2025-03-29T01:48:53Z

exercises/split-second-stopwatch/instructions.md

+
+- Start: start/resume time tracking
+- Stop: stop (pause) time tracking
+- Current lap: the time tracked for the current lap


Suggested change

- Current lap: the time tracked for the current lap

- Current lap: display the time tracked for the current lap

The other list items use a verb to indicate what we're doing with the tracked time.

BNAndras · 2025-03-29T01:49:23Z

exercises/split-second-stopwatch/instructions.md

+- Start: start/resume time tracking
+- Stop: stop (pause) time tracking
+- Current lap: the time tracked for the current lap
+- Previous laps: the times of all previously recorded laps


Suggested change

- Previous laps: the times of all previously recorded laps

- Previous laps: display the times of all previously recorded laps

The other list items use a verb to indicate what we're doing with the tracked time.

Also is this the running total or all the individual lap times?

"display" implies "STDOUT" to me, which isn't used in most tracks/exercises.

Track the time then?

Track could work. What would your preference be Isaac? BTW I agree with Isaac's sentiment

Retrieve the previously recorded lap times? I'm not sure if "track" would imply an implementation detail.

I also had a lot of trouble with current lap and previous laps when I initially reviewed. I intentionally left out the verbs because I wasn't sure what an appropriate verb would be. I intended to ask a question but completely forgot about it before posting the review.

BNAndras · 2025-03-29T01:51:05Z

exercises/split-second-stopwatch/instructions.md

+- Current lap: the time tracked for the current lap
+- Previous laps: the times of all previously recorded laps
+- Reset: stop time tracking, reset the current lap, and clear all previously recorded laps
+- Lap: add the current lap time to the previous laps and start a new lap


This line is unclear. Are we adding the lap time to a running total or keeping a history of the previous laps?

Well, sort of both. Lap does not influence the total running time, it's just a cutoff point where the current lap time is basically "stopped", then added to the previous laps and then the current lap time is reset in order to start counting from zero again

IsaacG · 2025-03-29T04:35:11Z

exercises/split-second-stopwatch/instructions.md

+- Start: start/resume time tracking
+- Stop: stop (pause) time tracking
+- Current lap: the time tracked for the current lap
+- Previous laps: the times of all previously recorded laps


"display" implies "STDOUT" to me, which isn't used in most tracks/exercises.

exercises/split-second-stopwatch/canonical-data.json

IsaacG · 2025-03-29T05:05:54Z

FWIW I wrote a simple semi-flexible tester that reads the tests from the JSON file and tests the implementation, in Python.

ErikSchierboom · 2025-03-30T08:56:29Z

I've tweaked a bit.

exercises/split-second-stopwatch/introduction.md

exercises/split-second-stopwatch/instructions.md

Co-authored-by: Anastasios Chatzialexiou <16361161+tasxatzial@users.noreply.github.com>

kotp · 2025-03-31T22:14:43Z

exercises/split-second-stopwatch/canonical-data.json

@@ -0,0 +1,194 @@
+{
+  "exercise": "split-second-stopwatch",
+  "comments": ["Times are formatted as 'HH:mm:ss'."],


This may not be clear in terms of "What do these letters mean". I mean to say that it may be intuitive that it is hour, minutes, seconds, but why the change in case for hours?

It can be useful to show a time where the HH is put in place, such as 13:14:15, to show the difference from a 12 hour clock to a twenty four hour clock. To others, it will be clear, but via experience rather than inherent knowledge.

Fair point! I'll update

IsaacG · 2025-04-06T19:48:18Z

exercises/split-second-stopwatch/canonical-data.json

+          {
+            "command": "lap"
+          },
+          ,


Suggested change

,

jq says invalid JSON.

IsaacG · 2025-04-07T03:58:15Z

exercises/split-second-stopwatch/canonical-data.json

+          },
+          {
+            "command": "currentLap",
+            "expected": ["00:00:00"]


Prior currentLap commands expect a string. This and the next expect a list.

Same for total below.

IsaacG · 2025-04-07T04:02:27Z

exercises/split-second-stopwatch/canonical-data.json

+            "command": "stop"
+          },
+          {
+            "command": "lap"


error: cannot lap a stopwatch that is not running

The tests suggest after calling stop the state is ready. The last test says lap cannot be called from a ready state. 7 other tests call stop (putting it into a ready state) then lap.

ErikSchierboom · 2025-04-08T14:28:52Z

Yeah, I'm still working on the canonical data. I'll fix it.

ErikSchierboom · 2025-04-09T07:33:47Z

I've updated and streamlined the canonical data as well as adding more test cases.
I've also attempted to make the introduction slightly less boring and the instructions more clear.

exercises/split-second-stopwatch/canonical-data.json

IsaacG · 2025-04-10T16:10:21Z

This data works with my implementation.
https://gist.github.com/IsaacG/cb84b0eb3a3e5aebfbb578e034d0ac55

» python stopwatch.py https://raw.githubusercontent.com/exercism/problem-specifications/20911be341111aa85715740890eafff65ba11936/exercises/split-second-stopwatch/canonical-data.json
{'pass': 39, 'fail': 0}

exercises/split-second-stopwatch/instructions.md

exercises/split-second-stopwatch/canonical-data.json

ErikSchierboom · 2025-04-13T05:24:34Z

This is now ready for another round of reviews

exercises/split-second-stopwatch/canonical-data.json

Co-authored-by: Anastasios Chatzialexiou <16361161+tasxatzial@users.noreply.github.com>

ErikSchierboom · 2025-04-15T10:52:49Z

@BNAndras could you maybe also check the latest version?

BNAndras

Approving with one small potential tweak.

exercises/split-second-stopwatch/introduction.md

Co-authored-by: András B Nagy <20251272+BNAndras@users.noreply.github.com>

Add split-second-stopwatch exercise

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tasxatzial reviewed Mar 28, 2025

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BNAndras reviewed Mar 29, 2025

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ErikSchierboom added 2 commits March 30, 2025 10:53

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kotp reviewed Mar 31, 2025

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ErikSchierboom added 6 commits April 5, 2025 16:18

Clarify instructions

31f0e40

Explain time format

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Add stop state

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Add more test cases

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Remove nesting

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Add state diagram

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IsaacG reviewed Apr 6, 2025

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{

"command": "lap"

},

,

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Suggested change

,

jq says invalid JSON.

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Start improving instructions

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ErikSchierboom added 4 commits April 9, 2025 09:18

Fix canonical data

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Fix uuids

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Fix time

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ErikSchierboom marked this pull request as ready for review April 9, 2025 07:31

ErikSchierboom requested a review from a team as a code owner April 9, 2025 07:31

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ErikSchierboom added 2 commits April 10, 2025 18:47

lowercase commands

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ErikSchierboom merged commit f8c8521 into main Apr 15, 2025
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ErikSchierboom deleted the split-second-stopwatch branch April 15, 2025 16:51

	- Current lap: the time tracked for the current lap
	- Current lap: display the time tracked for the current lap

	- Previous laps: the times of all previously recorded laps
	- Previous laps: display the times of all previously recorded laps

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Add split-second-stopwatch exercise #2547

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ErikSchierboom commented Apr 15, 2025

Add `split-second-stopwatch` exercise #2547

Add `split-second-stopwatch` exercise #2547

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