t1092: add tests for git diff-files

Before integrating the 'git diff-files' builtin
with the sparse index feature, add tests to
t1092-sparse-checkout-compatibility.sh to ensure it currently works
with sparse-checkout and will still work with sparse index
after that integration.

When adding tests against a sparse-checkout
definition, we test two modes: all changes are
within the sparse-checkout cone and some changes are outside
the sparse-checkout cone.

In order to have staged changes outside of
the sparse-checkout cone, create a 'newdirectory/testfile' and
add it to the index, while leaving it outside of
the sparse-checkout definition.Test 'newdirectory/testfile'
being present on-disk without modifications, then change content inside
'newdirectory/testfile' in order to test 'newdirectory/testfile'
being present on-disk with modifications.

Signed-off-by: Shuqi Liang <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Cheskaqiqi

t/t1092-sparse-checkout-compatibility.sh

@@ -2055,4 +2055,52 @@ test_expect_success 'grep sparse directory within submodules' '
 	test_cmp actual expect
 '
 
+test_expect_success 'diff-files with pathspec inside sparse definition' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>"$1"
+	EOF
+
+	run_on_all ../edit-contents deep/a &&
+
+	test_all_match git diff-files &&
+
+	test_all_match git diff-files deep/a
+
+'
+
+test_expect_success 'diff-files with pathspec outside sparse definition' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>"$1"
+	EOF
+
+	# add file to the index but outside of cone
+	run_on_sparse mkdir newdirectory &&
+	run_on_sparse ../edit-contents newdirectory/testfile &&
+	test_sparse_match git add --sparse newdirectory/testfile &&
+
+	# file present on-disk without modifications
+	test_sparse_match git diff-files &&
+	test_must_be_empty sparse-checkout-out &&
+	test_must_be_empty sparse-checkout-err &&
+	test_sparse_match git diff-files newdirectory/testfile &&
+	test_must_be_empty sparse-checkout-out &&
+	test_must_be_empty sparse-checkout-err &&
+
+	# file present on-disk with modifications
+	FN=newdirectory/testfile &&
+	OID=$(git -C sparse-checkout hash-object $FN) &&
+	ZERO=$(test_oid zero) &&
+	echo ":100644 100644 $OID $ZERO M	$FN" >expect &&
+
+	run_on_sparse ../edit-contents newdirectory/testfile &&
+	test_sparse_match git diff-files &&
+	test_cmp expect sparse-checkout-out &&
+	test_sparse_match git diff-files newdirectory/testfile &&
+	test_cmp expect sparse-checkout-out
+'
+
 test_done