Split tests with pytest-split

.github/workflows/test.yml

@@ -26,6 +26,19 @@ jobs:
       matrix:
         os: [ ubuntu-latest, macos-latest, windows-latest ]
         python-version: [ "3.8", "3.12" ]
+        include:
+          # pytest-split handles dividing the tests into n groups indexed 1...n.
+          # The tests are automatically split so that the expected duration of each
+          # group is roughly the same.
+          - os: ubuntu-latest
+            pytest-split-total-groups: 3
+            pytest-split-group-index: [1, 2, 3]
+          - os: macos-latest
+            pytest-split-total-groups: 3
+            pytest-split-group-index: [1, 2, 3]
+          - os: windows-latest
+            pytest-split-total-groups: 5
+            pytest-split-group-index: [1, 2, 3, 4, 5]
     defaults:
       run:
         shell: bash -eo pipefail -l {0}
@@ -65,6 +78,8 @@ jobs:
             --cov=conda_lock --cov-branch --cov-report=xml --cov-report=term \
             --store-durations \
             --durations-path "${{ github.workspace }}/tests/durations/${{ matrix.os }}-py${{ matrix.python-version }}.json" \
+            --splits="${{ matrix.pytest-split-total-groups }}" \
+            --group="${{ matrix.pytest-split-group-index }}" \
             tests
           cp coverage.xml "${{ github.workspace }}"