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Diffstat (limited to 'Documentation/git-bisect.txt')
| -rw-r--r-- | Documentation/git-bisect.txt | 68 |
1 files changed, 44 insertions, 24 deletions
diff --git a/Documentation/git-bisect.txt b/Documentation/git-bisect.txt index c39d957c3a..c443e0f307 100644 --- a/Documentation/git-bisect.txt +++ b/Documentation/git-bisect.txt @@ -241,7 +241,12 @@ exit(3) manual page), as the value is chopped with "& 0377". The special exit code 125 should be used when the current source code cannot be tested. If the script exits with this code, the current -revision will be skipped (see `git bisect skip` above). +revision will be skipped (see `git bisect skip` above). 125 was chosen +as the highest sensible value to use for this purpose, because 126 and 127 +are used by POSIX shells to signal specific error status (127 is for +command not found, 126 is for command found but not executable---these +details do not matter, as they are normal errors in the script, as far as +"bisect run" is concerned). You may often find that during a bisect session you want to have temporary modifications (e.g. s/#define DEBUG 0/#define DEBUG 1/ in a @@ -274,53 +279,68 @@ $ git bisect start HEAD origin -- # HEAD is bad, origin is good $ git bisect run make test # "make test" builds and tests ------------ -* Automatically bisect a broken test suite: +* Automatically bisect a broken test case: + ------------ $ cat ~/test.sh #!/bin/sh -make || exit 125 # this skips broken builds -make test # "make test" runs the test suite -$ git bisect start v1.3 v1.1 -- # v1.3 is bad, v1.1 is good +make || exit 125 # this skips broken builds +~/check_test_case.sh # does the test case pass? +$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10 $ git bisect run ~/test.sh ------------ + Here we use a "test.sh" custom script. In this script, if "make" fails, we skip the current commit. +"check_test_case.sh" should "exit 0" if the test case passes, +and "exit 1" otherwise. + -It is safer to use a custom script outside the repository to prevent -interactions between the bisect, make and test processes and the -script. -+ -"make test" should "exit 0", if the test suite passes, and -"exit 1" otherwise. +It is safer if both "test.sh" and "check_test_case.sh" are +outside the repository to prevent interactions between the bisect, +make and test processes and the scripts. -* Automatically bisect a broken test case: +* Automatically bisect with temporary modifications (hot-fix): + ------------ $ cat ~/test.sh #!/bin/sh -make || exit 125 # this skips broken builds -~/check_test_case.sh # does the test case passes ? -$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10 -$ git bisect run ~/test.sh + +# tweak the working tree by merging the hot-fix branch +# and then attempt a build +if git merge --no-commit hot-fix && + make +then + # run project specific test and report its status + ~/check_test_case.sh + status=$? +else + # tell the caller this is untestable + status=125 +fi + +# undo the tweak to allow clean flipping to the next commit +git reset --hard + +# return control +exit $status ------------ + -Here "check_test_case.sh" should "exit 0" if the test case passes, -and "exit 1" otherwise. -+ -It is safer if both "test.sh" and "check_test_case.sh" scripts are -outside the repository to prevent interactions between the bisect, -make and test processes and the scripts. +This applies modifications from a hot-fix branch before each test run, +e.g. in case your build or test environment changed so that older +revisions may need a fix which newer ones have already. (Make sure the +hot-fix branch is based off a commit which is contained in all revisions +which you are bisecting, so that the merge does not pull in too much, or +use `git cherry-pick` instead of `git merge`.) -* Automatically bisect a broken test suite: +* Automatically bisect a broken test case: + ------------ $ git bisect start HEAD HEAD~10 -- # culprit is among the last 10 $ git bisect run sh -c "make || exit 125; ~/check_test_case.sh" ------------ + -Does the same as the previous example, but on a single line. +This shows that you can do without a run script if you write the test +on a single line. Author ------ |