Changes since v8:

* Fix white space problem.

* Simplified the refactored function based on Victoria's suggestion.

Shuqi Liang (2):
  t1092: add tests for `git diff-files`
  diff-files: integrate with sparse index

 builtin/diff-files.c                     |  4 ++
 t/perf/p2000-sparse-operations.sh        |  2 +
 t/t1092-sparse-checkout-compatibility.sh | 73 +++++++++++++++++++++++-
 3 files changed, 77 insertions(+), 2 deletions(-)

Range-diff against v8:
1:  d7f921c1a6 ! 1:  d78513af83 t1092: add tests for `git diff-files`
    @@ t/t1092-sparse-checkout-compatibility.sh: test_expect_success 'sparse-index is n
     +
     +	test_all_match git diff-files &&
     +
    -+	test_all_match git diff-files deep/a && 
    ++	test_all_match git diff-files deep/a &&
     +
     +	# test wildcard
     +	test_all_match git diff-files "deep/*"
    @@ t/t1092-sparse-checkout-compatibility.sh: test_expect_success 'sparse-index is n
     +	EOF
     +
     +	# Add file to the index but outside of cone for sparse-checkout cases.
    -+	# Add file to the index without sparse-checkout cases to ensure all have 
    ++	# Add file to the index without sparse-checkout cases to ensure all have
     +	# same output.
     +	run_on_all mkdir -p folder1 &&
     +	run_on_all cp a folder1/a &&
    @@ t/t1092-sparse-checkout-compatibility.sh: test_expect_success 'sparse-index is n
     +	run_on_all ../edit-contents folder1/a &&
     +	test_all_match git diff-files &&
     +	test_all_match git diff-files folder1/a &&
    -+	test_all_match git diff-files "folder*/a" 
    ++	test_all_match git diff-files "folder*/a"
     +'
     +
      test_done
2:  b44384ac94 ! 2:  a2454befa0 diff-files: integrate with sparse index
    @@ t/t1092-sparse-checkout-compatibility.sh: test_expect_success 'index.sparse disa
      '
      
     -ensure_not_expanded () {
    -+ensure_index_state () {
    -+	local expected_expansion="$1"
    -+	shift
    -+
    ++run_sparse_index_trace2 () {
      	rm -f trace2.txt &&
      	if test -z "$WITHOUT_UNTRACKED_TXT"
      	then
     @@ t/t1092-sparse-checkout-compatibility.sh: ensure_not_expanded () {
    + 			git -C sparse-index "$@" \
      			>sparse-index-out \
      			2>sparse-index-error || return 1
    - 	fi &&
    --	test_region ! index ensure_full_index trace2.txt
    -+
    -+	if [ "$expected_expansion" = "expanded" ]
    -+	then
    -+		test_region index ensure_full_index trace2.txt
    -+	else
    -+		test_region ! index ensure_full_index trace2.txt
    +-	fi &&
     +	fi
     +}
     +
     +ensure_expanded () {
    -+	ensure_index_state "expanded" "$@"
    ++	run_sparse_index_trace2 "$@" &&
    ++	test_region index ensure_full_index trace2.txt
     +}
     +
     +ensure_not_expanded () {
    -+	ensure_index_state "not_expanded" "$@"
    ++	run_sparse_index_trace2 "$@" &&
    + 	test_region ! index ensure_full_index trace2.txt
      }
      
    - test_expect_success 'sparse-index is not expanded' '
     @@ t/t1092-sparse-checkout-compatibility.sh: test_expect_success 'diff-files with pathspec outside sparse definition' '
    - 	test_all_match git diff-files "folder*/a" 
    + 	test_all_match git diff-files "folder*/a"
      '
      
     +test_expect_success 'sparse index is not expanded: diff-files' '
-- 
2.39.0