linux-kernel - Re: [PATCH] kunit: log numbers in decimal and hex

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Date:   Sat, 15 Oct 2022 12:04:33 +0800
From:   David Gow <davidgow@...gle.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-kernel@...r.kernel.org, brendan.higgins@...ux.dev,
        kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH] kunit: log numbers in decimal and hex

On Thu, Oct 6, 2022 at 1:52 AM Mark Rutland <mark.rutland@....com> wrote:
>
> When KUNIT_EXPECT_EQ() or KUNIT_ASSERT_EQ() log a failure, they log the
> two values being compared, with numerical values logged in decimal.
>
> In some cases, decimal output is painful to consume, and hexadecimal
> output would be more helpful. For example, this is the case for tests
> I'm currently developing for the arm64 insn encoding/decoding code,
> where comparing two 32-bit instruction opcodes results in output such
> as:
>
> |  # test_insn_add_shifted_reg: EXPECTATION FAILED at arch/arm64/lib/test_insn.c:2791
> |  Expected obj_insn == gen_insn, but
> |      obj_insn == 2332164128
> |      gen_insn == 1258422304
>
> To make this easier to consume, this patch logs the values in both
> decimal and hexadecimal:
>
> |  # test_insn_add_shifted_reg: EXPECTATION FAILED at arch/arm64/lib/test_insn.c:2791
> |  Expected obj_insn == gen_insn, but
> |      obj_insn == 2332164128 (0x8b020020)
> |      gen_insn == 1258422304 (0x4b020020)
>
> As can be seen from the example, having hexadecimal makes it
> significantly easier for a human to spot which specific bits are
> incorrect.
>
> Signed-off-by: Mark Rutland <mark.rutland@....com>
> Cc: Brendan Higgins <brendan.higgins@...ux.dev>
> Cc: David Gow <davidgow@...gle.com>
> Cc: linux-kselftest@...r.kernel.org
> Cc: kunit-dev@...glegroups.com
> ---

Thanks very much: this will definitely be useful. I tend to agree with
Daniel that this could clutter things up a bit, but I think the other
options (a separate ASSERT_EQ_HEX() macro, or a heuristic to remove it
for, e.g., values <= 9) add more complexity than benefit there.

So let's go with this as-is.

Reviewed-by: David Gow <davidgow@...gle.com>

Cheers,
-- David

>  lib/kunit/assert.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/lib/kunit/assert.c b/lib/kunit/assert.c
> index d00d6d181ee8..24dec5b48722 100644
> --- a/lib/kunit/assert.c
> +++ b/lib/kunit/assert.c
> @@ -127,13 +127,15 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
>                           binary_assert->text->right_text);
>         if (!is_literal(stream->test, binary_assert->text->left_text,
>                         binary_assert->left_value, stream->gfp))
> -               string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld\n",
> +               string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld (0x%llx)\n",
>                                   binary_assert->text->left_text,
> +                                 binary_assert->left_value,
>                                   binary_assert->left_value);
>         if (!is_literal(stream->test, binary_assert->text->right_text,
>                         binary_assert->right_value, stream->gfp))
> -               string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld",
> +               string_stream_add(stream, KUNIT_SUBSUBTEST_INDENT "%s == %lld (0x%llx)",
>                                   binary_assert->text->right_text,
> +                                 binary_assert->right_value,
>                                   binary_assert->right_value);
>         kunit_assert_print_msg(message, stream);
>  }
> --
> 2.30.2
>