> I think these changes are good, but it's not the case that we try to > avoid using pipes at all in our tests. > > It's often a hassle, and just not worth it, e.g.: > > oid=$(echo foo | git hash-object --stdin -w) && > > Sure, we can make that: > > echo foo >in && > oid=$(git hash-object --stdin -w <in) && > > But in the general case it's not worth worrying about. > > What we *do* try to avoid, and what's actually important is to never > invoke "git" or other programs we invoke on the LHS of a pipe, or to > otherwise do so in a way that hides potential errors. Sorry, I have not mentioned it properly in the message but my intention is not to remove all pipes but to remove only those, which have "git" command in LHS. > That's not isolated to just pipes, but e.g. calling it within helper > functions that don't &&-chain, but pipes are probably the most common > offender. > > The reason we do that is because in hacking git we may make it error, > segfault etc. If it's on the LHS of a pipe that failure becomes > indistinguishable from success. > > And if the test is really checking e.g. "when I run git like this, it > produces no output" printing nothing with an exit of 0 will become the > same as a segafault for the purposes of test. > > And that's bad. > > But just invoking things on the LHS of a pipe? Sometimes it's a good > thing not do do that, because we'll be able to see a failure more > incrementally, and with intermediate files. > > But it's generally not a problem, our test suite assumes that the OS is > basically sane. We're not going to call every invocation of "sed", > "grep" etc. with a wrapper like "test_must_fail grep" instead of "! > grep". > > The same goes for our own helper utility functions such as "q_to_nul" > etc, as long as (and this is critical) that they're implemented by > shelling out to "sed", "grep", "perl" or whatever, and not to "git" or > "test-tool" etc. Then we need to start being as paranoid about them as > "git" on the LHS of pipes. Thanks here for providing me with a broader context of the problem. What I understand, It's not just about "git" on LHS of pipes but more broader to anything custom where We can miss exit codes but I think as a low hanging fruit I can start with "git" on LHS of pipe and as I will understand the codebase more I can work on other custom helpers too. Thanks, Shubham
