On Fri, Feb 09, 2018 at 03:42:34AM +0100, SZEDER Gábor wrote: > To check that a git command fails and to inspect its error message we > usually execute a command like this throughout our test suite: > > test_must_fail git command --option 2>output.err > > Note that this command doesn't limit the redirection to the git > command, but it redirects the standard error of the 'test_must_fail' > helper function as well. This is wrong for several reasons: > > - If that git command were to succeed or die for an unexpected > reason e.g. signal, then 'test_must_fail's helpful error message > would end up in the given file instead of on the terminal or in > 't/test-results/$T.out', when the test is run with '-v' or > '--verbose-log', respectively. > > - If the test is run with '-x', the trace of executed commands in > 'test_must_fail' will go to stderr as well (except for more recent > Bash versions supporting $BASH_XTRACEFD), and then in turn will > end up in the given file.
I have to admit that I'm slightly negative on this approach, just because: 1. It requires every caller to do something special, rather than just using normal redirection. And the feature isn't as powerful as redirection. E.g., some callers do: test_must_fail foo >output 2>&1 But: test_must_fail stderr=output foo >output is not quite right (stdout and stderr outputs may clobber each other, because they have independent position pointers). 2. The "-x" problems aren't specific to test_must_fail at all. They're a general issue with shell functions. I'm not entirely happy with saying "if you want to use -x, please use bash". But given that it actually solves the problems everywhere with no further effort, is it really that bad a solution? For the error messages from test_must_fail, could we go in the same direction, and send them to descriptor 4 rather than 2? We've already staked out descriptor 4 as something magical that must be left alone (see 9be795fb). If we can rely on that, then it becomes a convenient way for functions to make sure their output is going to the script's stderr. -Peff