Re: [PATCH 2/7] sparse-index: update command for expand/collapse test

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 30, 2021, 21:32 UTC
Message-ID: <xmqqk0ixagw8.fsf@gitster.g>
In-Reply-To: <6e9843d5-bc04-e69c-9e53-7bf18ca30fc8@github.com>

Victoria Dye <vdye@github.com> writes:

Show 20 quoted lines

> Taylor Blau wrote:
>> On Thu, Sep 30, 2021 at 02:50:56PM +0000, Victoria Dye via GitGitGadget wrote:
>>> From: Victoria Dye <vdye@github.com>
>>>
>>> In anticipation of multiple commands being fully integrated with sparse
>>> index, update the test for index expand and collapse for non-sparse index
>>> integrated commands to use `mv`.
>>> ...
>>>  	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
>>> -		git -C sparse-index -c core.fsmonitor="" reset --hard &&
>>> +		git -C sparse-index -c core.fsmonitor="" mv a b &&
>> 
>> Double-checking my understanding as somebody who is not so familiar with
>> t1092: this test is to ensure that commands which don't yet understand
>> the sparse index can temporarily expand it in order to do their work?
>
> Exactly - if a command doesn't explicitly enable use of the sparse index by
> setting `command_requires_full_index` to 0, the index is expanded if/when it
> is first read during the command's execution and collapsed if/when it is
> written to disk. This test makes sure that mechanism works as intended.

Sorry, I do not quite follow.

So is this "before this series of patches, 'reset --hard' can be used to as a sample of a command that expands and then collapses, but because it no longer is a good sample of a command so we replace it with 'mv a b'"? Do we need to update this further when "mv a b" learns to expand and then collapse?