t/README: suggest how to leave test early with failure

index 9afd61e3ca..fd2f7489a9 100644 --- a/t/README +++ b/t/README @@ -550,6 +550,41 @@ Here are the "do's:" reports "ok" or "not ok" to the end user running the tests. Under --verbose, they are shown to help debug the tests. + - Be careful when you loop + + You may need to verify multiple things in a loop, but the + following does not work correctly: + + test_expect_success 'test three things' ' + for i in one two three + do + test_something "$i" + done && + test_something_else + ' + + Because the status of the loop itself is the exit status of the + test_something in the last round, the loop does not fail when + "test_something" for "one" or "two" fails. This is not what you + want. + + Instead, you can break out of the loop immediately when you see a + failure. Because all test_expect_* snippets are executed inside + a function, "return 1" can be used to fail the test immediately + upon a failure: + + test_expect_success 'test three things' ' + for i in one two three + do + test_something "$i" || return 1 + done && + test_something_else + ' + + Note that we still &&-chain the loop to propagate failures from + earlier commands. + + And here are the "don'ts:" - Don't exit() within a <script> part.