The best replacement for test case is test script.

The best alternatives to test case are rated as following:
★★★★★  test script
★★★★  use case
★★  test plan
★★  test scenario
★★  test procedure
★  test suite
★  scenario
★  test condition
★  user story
  script
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  checklist
  system test case

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Speaking about test case, one probably shouldn't forget about sample scenario.

Other search terms related to test case and their ratings are:
★★★★★ sample scenario
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