Re: [PATCH v1] read-cache: add GIT_TEST_INDEX_VERSION support

From: Ben Peart <peartben@gmail.com>
Date: Sep 13, 2018, 14:07 UTC
Message-ID: <4f8b4664-6108-db7f-cb40-2bc55d9edece@gmail.com>
In-Reply-To: <20180912223101.GA1719@hank.intra.tgummerer.com>

On 9/12/2018 6:31 PM, Thomas Gummerer wrote:

Show 17 quoted lines

> On 09/12, Ben Peart wrote:
>> Teach get_index_format_default() to support running the test suite
>> with specific index versions.  In particular, this enables the test suite
>> to be run using index version 4 which is not the default so gets less testing.
> 
> I found this commit message slightly misleading.  Running the test
> suite with specific index versions is already supported, by defining
> TEST_GIT_INDEX_VERSION in 'config.mak'.  What we're doing here is
> introduce an additional environment variable that can also be used to
> set the index format in tests.
> 
> Even setting TEST_GIT_INDEX_VERSION=4 in the environment does run the
> test suite with index-v4.  Admittedly the name is a bit strange
> compared to our usual GIT_TEST_* environment variable names, and it
> should probably be documented better (it's only documented in the
> Makefile currently), but I'm not sure we should introduce another
> environment variable for this purpose?

TEST_GIT_INDEX_VERSION enables the testing I was looking for but you're right, it isn't well documented and the atypical naming and implementation don't help either.

I checked the documentation and code but didn't see any way to test the V4 index code path so wrote this patch. I wonder if we can improve the discoverability of TEST_GIT_INDEX_VERSION through better naming and documentation.

How about this as an alternative?

diff --git a/Makefile b/Makefile
index 5a969f5830..9e84ef02f7 100644
--- a/Makefile
+++ b/Makefile
@@ -400,7 +400,7 @@ all::
  # (defaults to "man") if you want to have a different default when
  # "git help" is called without a parameter specifying the format.
  #
-# Define TEST_GIT_INDEX_VERSION to 2, 3 or 4 to run the test suite
+# Define GIT_TEST_INDEX_VERSION to 2, 3 or 4 to run the test suite
  # with a different indexfile format version.  If it isn't set the index
  # file format used is index-v[23].
  #
@@ -2599,8 +2599,8 @@ endif
  ifdef GIT_INTEROP_MAKE_OPTS
         @echo GIT_INTEROP_MAKE_OPTS=\''$(subst ','\'',$(subst 
','\'',$(GIT_INTEROP_MAKE_OPTS)))'\' >>$@+
  endif
-ifdef TEST_GIT_INDEX_VERSION
-       @echo TEST_GIT_INDEX_VERSION=\''$(subst ','\'',$(subst 
','\'',$(TEST_GIT_INDEX_VERSION)))'\' >>$@+
+ifdef GIT_TEST_INDEX_VERSION
+       @echo GIT_TEST_INDEX_VERSION=\''$(subst ','\'',$(subst 
','\'',$(GIT_TEST_INDEX_VERSION)))'\' >>$@+

  endif
         @if cmp $@+ $@ >/dev/null 2>&1; then $(RM) $@+; else mv $@+ $@; fi

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 44288cbb59..31698c01c4 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -134,9 +134,9 @@ export EDITOR
  GIT_TRACE_BARE=1
  export GIT_TRACE_BARE

-if test -n "${TEST_GIT_INDEX_VERSION:+isset}"
+if test -n "${GIT_TEST_INDEX_VERSION:+isset}"
  then
-       GIT_INDEX_VERSION="$TEST_GIT_INDEX_VERSION"
+       GIT_INDEX_VERSION="$GIT_TEST_INDEX_VERSION"
         export GIT_INDEX_VERSION
  fi

diff --git a/t/README b/t/README
index 9028b47d92..f872638a78 100644
--- a/t/README
+++ b/t/README
@@ -315,10 +315,14 @@ packs on demand. This normally only happens when 
the object size is
   over 2GB. This variable forces the code path on any object larger than
   <n> bytes.

-GIT_TEST_OE_DELTA_SIZE=<n> exercises the uncomon pack-objects code
+GIT_TEST_OE_DELTA_SIZE=<n> exercises the uncommon pack-objects code
   path where deltas larger than this limit require extra memory
   allocation for bookkeeping.

+GIT_TEST_INDEX_VERSION=<n> exercises the index read/write code path
+for the index version specified.  Can be set to any valid version
+but the non-default version 4 is probably the most beneficial.
+
   Naming Tests
   ------------