test split and combined #522

Job	Run time
call / tests (windows-latest, tests)	3m 24s
call / tests (macos-latest, tests)	1m 28s
call / validate (ubuntu-latest, 3.12, validate)	2m 20s
call / checks (ubuntu-latest, 3.13)	1m 23s
call / checks (ubuntu-latest, 3.10)	1m 21s
call / checks (ubuntu-24.04, 3.11)	1m 16s
	11m 12s

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