[PATCH v2 0/2] jx/fetch-atomic-error-message-fix

From: Jiang Xin <zhiyou.jx@alibaba-inc.com>

# Changes since v1:

1. Add a "test_commit ..." command in test case of t5574, so we can run
   test cases 4-6 individually.

2. Improve commit logs.

# range-diff v1...v2

1:  8c85f83e66 ! 1:  210191917b t5574: test porcelain output of atomic fetch
    @@ Commit message
     
             test_must_be_empty stderr
     
    -    Refactor this test case to run it twice. The first time will be run
    -    using non-atomic fetch and the other time will be run using atomic
    -    fetch. We can see that the above assertion fails for atomic get, as
    -    shown below:
    +    But this assertion fails if using atomic fetch. Refactor this test case
    +    to use different fetch options by splitting it into three test cases.
     
    +      1. "setup for fetch porcelain output".
    +
    +      2. "fetch porcelain output": for non-atomic fetch.
    +
    +      3. "fetch porcelain output (atomic)": for atomic fetch.
    +
    +    Add new command "test_commit ..." in the first test case, so that if we
    +    run these test cases individually (--run=4-6), "git rev-parse HEAD~"
    +    command will work properly. Run the above test cases, we can find that
    +    one test case has a known breakage, as shown below:
    +
    +        ok 4 - setup for fetch porcelain output
             ok 5 - fetch porcelain output  # TODO known breakage vanished
             not ok 6 - fetch porcelain output (atomic) # TODO known breakage
     
    -    The failed test case had an error message with only the error prompt but
    +    The failed test case has an error message with only the error prompt but
         no message body, as follows:
     
             'stderr' is not empty, it contains:
    @@ Commit message
         In a later commit, we will fix this issue.
     
         Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
     
      ## t/t5574-fetch-output.sh ##
     @@ t/t5574-fetch-output.sh: test_expect_success 'fetch compact output' '
    @@ t/t5574-fetch-output.sh: test_expect_success 'fetch compact output' '
     +test_expect_success 'setup for fetch porcelain output' '
      	# Set up a bunch of references that we can use to demonstrate different
      	# kinds of flag symbols in the output format.
    ++	test_commit commit-for-porcelain-output &&
      	MAIN_OLD=$(git rev-parse HEAD) &&
    + 	git branch "fast-forward" &&
    + 	git branch "deleted-branch" &&
     @@ t/t5574-fetch-output.sh: test_expect_success 'fetch porcelain output' '
      	FORCE_UPDATED_OLD=$(git rev-parse HEAD) &&
      	git checkout main &&
2:  d3184a9d0f ! 2:  6fb83a0000 fetch: no redundant error message for atomic fetch
    @@ Commit message
         will appear at the end of do_fetch(). It was introduced in b3a804663c
         (fetch: make `--atomic` flag cover backfilling of tags, 2022-02-17).
     
    -    Instead of displaying the error message unconditionally, the final error
    -    output should follow the pattern in update-ref.c and files-backend.c as
    -    follows:
    +    In function do_fetch(), a failure message is already shown before the
    +    retcode is set, so we should not call additional error() at the end of
    +    this function.
    +
    +    We can remove the redundant error() function, because we know that
    +    the function ref_transaction_abort() never fails. While we can find a
    +    common pattern for calling ref_transaction_abort() by running command
    +    "git grep -A1 ref_transaction_abort", e.g.:
     
             if (ref_transaction_abort(transaction, &error))
                 error("abort: %s", error.buf);
     
    -    This will fix the test case "fetch porcelain output (atomic)" in t5574.
    +    We can fix this issue follow this pattern, and the test case "fetch
    +    porcelain output (atomic)" in t5574 will also be fixed. If in the future
    +    we decide that we don't need to check the return value of the function
    +    ref_transaction_abort(), this change can be fixed along with it.
     
         Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
     
      ## builtin/fetch.c ##
     @@ builtin/fetch.c: static int do_fetch(struct transport *transport,

Jiang Xin (2):
  t5574: test porcelain output of atomic fetch
  fetch: no redundant error message for atomic fetch

 builtin/fetch.c         |  4 +-
 t/t5574-fetch-output.sh | 97 ++++++++++++++++++++++++-----------------
 2 files changed, 59 insertions(+), 42 deletions(-)