Re: [PATCH v4] t3310: avoid hiding failures from rev-parse in command substitutions

> Running `git` commands inside command substitutions like
>
>     test "$(git rev-parse A)" = "$(git rev-parse B)"
>
> can hide failures from the `git` invocations and provide little
> diagnostic information when `test` fails.
>
> Use `test_cmp` when comparing against a stored expected value so
> mismatches show both expected and actual output. Use `test_cmp_rev`
> when comparing two revisions. These helpers produce clearer failure
> output, making it easier to understand what went wrong.
>
> Suggested-by: Eric Sunshine <sunshine@sunshineco.com>
> Signed-off-by: Francesco Paparatto <francescopaparatto@gmail.com>
> ---
> @@ -569,13 +578,15 @@ EOF
> -       test_grep -q "$(git rev-parse refs/notes/m)" output &&
> -       test_grep -q "$(git rev-parse NOTES_MERGE_PARTIAL^1)" output &&
> +       oid=$(git rev-parse refs/notes/m) &&
> +       test_grep -q "$oid" output &&
> +       oid=$(git rev-parse NOTES_MERGE_PARTIAL^1) &&
> +       test_grep -q "$oid" output &&
> @@ -606,8 +617,8 @@ test_expect_success 'switch cwd before committing notes merge' '
> -               echo "foo" > $(git rev-parse HEAD) &&
> -               echo "bar" >> $(git rev-parse HEAD) &&
> +               oid=$(git rev-parse HEAD) &&
> +               test_write_lines foo bar >"$oid" &&