3/5 refactor: pass durations dict into algorithms#122
Open
vokracko wants to merge 3 commits intojerry-git:masterfrom
Open
3/5 refactor: pass durations dict into algorithms#122vokracko wants to merge 3 commits intojerry-git:masterfrom
vokracko wants to merge 3 commits intojerry-git:masterfrom
Conversation
The previous setup relied on pytest-cov (``--cov pytest_split --cov tests`` in addopts) which has a long-standing limitation when measuring a pytest plugin: the plugin imports happen during pytest's plugin discovery, *before* pytest-cov starts tracing. Anything that runs at import time (class bodies, decorators, type aliases, enum definitions) is reported as uncovered even though it obviously executed - the plugin wouldn't load otherwise. The ``CoverageWarning: Module pytest_split was previously imported, but not measured`` made that explicit. The cookiecutter template the project was generated from worked around this by adding ``--cov tests`` to the addopts, inflating the denominator with 100%-covered test files so the average reached 90%. That pulled the number up but stopped reporting the actual source coverage. Switch to ``coverage run -m pytest`` followed by ``coverage report``. Running ``coverage`` from the outside means tracing starts before Python imports anything at all, so plugin import-time code is counted. Real source coverage jumps from ~74% to 99%; threshold goes from 90 to 95 to reflect that.
Tests previously asserted each TestGroup field separately (`first.selected`, `first.deselected`, `first.duration`). Consolidate to a single equality check against an expected TestGroup, with concrete values for every field rather than only ``selected``.
Tighten the algorithm contract so each one receives a single data argument: a dict mapping pytest items to their durations. Promote the helper that builds the dict to a public name (compute_durations) and inline the two helpers that only it used. The plugin builds the dict once and passes it to the algorithm. Algorithm bodies otherwise consume the same (item, duration) stream they did before, so behaviour is unchanged. Sets up follow-ups that separate group membership from within-group ordering.
This was referenced Apr 29, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Third of five stacked PRs that fix #25.
Motivation. The next PR (4/5) will move within-group ordering out of the algorithms and into the plugin. Doing that cleanly first requires the algorithms to take a single, tight data input. Today's signature
(splits, items, durations)mixes the test list with the lookup dict; subsequent steps benefit from a singledict[Item, float]argument that pairs items with their resolved durations up front.What changes.
AlgorithmBase.__call__takes(splits, durations: dict[Item, float])instead of(splits, items, durations). The previously-private_get_items_with_durationshelper is promoted to publiccompute_durations, with the two single-call-site helpers it used (_remove_irrelevant_durations,_get_avg_duration_per_test) inlined. The plugin builds the dict once viacompute_durationsand passes it to the chosen algorithm.No observable behaviour change.
AlgorithmBaseneed to update — the new signature is(splits, durations), andcompute_durations(items, cached_durations)builds the dict the same way the plugin does.Stack.
coverage run→ 1/5 build: measure coverage on source only via coverage run #120TestGroupdirectly → 2/5 refactor: assert TestGroup directly in algorithm tests #121duration_based_chunks— closes Splits invalid when collection order not deterministic #25 → 5/5 fix: stabilise duration_based_chunks across collection orders #124