linux-kernel - Re: [PATCH v8] fat: Add KUnit tests for checksums and timestamps

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Message-ID: <YJGUFrc8PJ0LAKiF@google.com>
Date:   Tue, 4 May 2021 11:36:06 -0700
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     David Gow <davidgow@...gle.com>
Cc:     OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>, shuah@...nel.org,
        kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8] fat: Add KUnit tests for checksums and timestamps

On Thu, Apr 15, 2021 at 11:56:23PM -0700, David Gow wrote:
> Add some basic sanity-check tests for the fat_checksum() function and
> the fat_time_unix2fat() and fat_time_fat2unix() functions. These unit
> tests verify these functions return correct output for a number of test
> inputs.
> 
> These tests were inspored by -- and serve a similar purpose to -- the
                   ^^^^^^^^
        I am guessing this is supposed to be "inspired".

> timestamp parsing KUnit tests in ext4[1].
> 
> Note that, unlike fat_time_unix2fat, fat_time_fat2unix wasn't previously
> exported, so this patch exports it as well. This is required for the
> case where we're building the fat and fat_test as modules.
> 
> [1]:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/ext4/inode-test.c
> 
> Signed-off-by: David Gow <davidgow@...gle.com>
> Acked-by: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>

Aside from the nit above, and the *potential* nit and question below.
Everything here looks good to me.

Reviewed-by: Brendan Higgins <brendanhiggins@...gle.com>

> ---
> 
> It's been a while, but this hopefully is a final version of the FAT KUnit
> patchset. It has a number of changes to keep it up-to-date with current
> KUnit standards, notably the use of parameterised tests and the addition
> of a '.kunitconfig' file to allow for easy testing. It also fixes an
> endianness tagging issue picked up by the kernel test robot under sparse
> on pa-risc.
> 
> Cheers,
> -- David

[...]

> diff --git a/fs/fat/fat_test.c b/fs/fat/fat_test.c
> new file mode 100644
> index 000000000000..febd25f57d4b
> --- /dev/null
> +++ b/fs/fat/fat_test.c
> @@ -0,0 +1,197 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * KUnit tests for FAT filesystems.
> + *
> + * Copyright (C) 2020 Google LLC.

Nit: I know you wrote this last year, but I have had other maintainers
tell me the Copyright date should be set to when the final version of
the patch is sent out.

I personally don't care, and I don't think you should resend this patch
just for that, but figured I would mention.

> + * Author: David Gow <davidgow@...gle.com>
> + */
> +
> +#include <kunit/test.h>
> +
> +#include "fat.h"
> +
> +static void fat_checksum_test(struct kunit *test)
> +{
> +	/* With no extension. */
> +	KUNIT_EXPECT_EQ(test, fat_checksum("VMLINUX    "), (u8)44);
> +	/* With 3-letter extension. */
> +	KUNIT_EXPECT_EQ(test, fat_checksum("README  TXT"), (u8)115);
> +	/* With short (1-letter) extension. */
> +	KUNIT_EXPECT_EQ(test, fat_checksum("ABCDEFGHA  "), (u8)98);

How do you get the magic values? Or is this just supposed to be a
regression test?

Not going to pretend I understand FAT, but everything else in this test
makes sense from a logical/testing/readability point of view.

Cheers!

[...]