1 files changed, 110 insertions, 0 deletions
diff --git a/t/t4057-diff-combined-paths.sh b/t/t4057-diff-combined-paths.sh
new file mode 100755
index 0000000..9a7505c
--- /dev/null
+++ b/t/t4057-diff-combined-paths.sh
@@ -0,0 +1,110 @@
+#!/bin/sh
+
+test_description='combined diff show only paths that are different to all parents'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+TEST_PASSES_SANITIZE_LEAK=true
+. ./test-lib.sh
+
+# verify that diffc.expect matches output of
+# $(git diff -c --name-only HEAD HEAD^ HEAD^2)
+diffc_verify () {
+	git diff -c --name-only HEAD HEAD^ HEAD^2 >diffc.actual &&
+	test_cmp diffc.expect diffc.actual
+}
+
+test_expect_success 'trivial merge - combine-diff empty' '
+	for i in $(test_seq 1 9)
+	do
+		echo $i >$i.txt &&
+		git add $i.txt || return 1
+	done &&
+	git commit -m "init" &&
+	git checkout -b side &&
+	for i in $(test_seq 2 9)
+	do
+		echo $i/2 >>$i.txt || return 1
+	done &&
+	git commit -a -m "side 2-9" &&
+	git checkout main &&
+	echo 1/2 >1.txt &&
+	git commit -a -m "main 1" &&
+	git merge side &&
+	>diffc.expect &&
+	diffc_verify
+'
+
+
+test_expect_success 'only one truly conflicting path' '
+	git checkout side &&
+	for i in $(test_seq 2 9)
+	do
+		echo $i/3 >>$i.txt || return 1
+	done &&
+	echo "4side" >>4.txt &&
+	git commit -a -m "side 2-9 +4" &&
+	git checkout main &&
+	for i in $(test_seq 1 9)
+	do
+		echo $i/3 >>$i.txt || return 1
+	done &&
+	echo "4main" >>4.txt &&
+	git commit -a -m "main 1-9 +4" &&
+	test_must_fail git merge side &&
+	cat <<-\EOF >4.txt &&
+	4
+	4/2
+	4/3
+	4main
+	4side
+	EOF
+	git add 4.txt &&
+	git commit -m "merge side (2)" &&
+	echo 4.txt >diffc.expect &&
+	diffc_verify
+'
+
+test_expect_success 'merge introduces new file' '
+	git checkout side &&
+	for i in $(test_seq 5 9)
+	do
+		echo $i/4 >>$i.txt || return 1
+	done &&
+	git commit -a -m "side 5-9" &&
+	git checkout main &&
+	for i in $(test_seq 1 3)
+	do
+		echo $i/4 >>$i.txt || return 1
+	done &&
+	git commit -a -m "main 1-3 +4hello" &&
+	git merge side &&
+	echo "Hello World" >4hello.txt &&
+	git add 4hello.txt &&
+	git commit --amend &&
+	echo 4hello.txt >diffc.expect &&
+	diffc_verify
+'
+
+test_expect_success 'merge removed a file' '
+	git checkout side &&
+	for i in $(test_seq 5 9)
+	do
+		echo $i/5 >>$i.txt || return 1
+	done &&
+	git commit -a -m "side 5-9" &&
+	git checkout main &&
+	for i in $(test_seq 1 3)
+	do
+		echo $i/4 >>$i.txt || return 1
+	done &&
+	git commit -a -m "main 1-3" &&
+	git merge side &&
+	git rm 4.txt &&
+	git commit --amend &&
+	echo 4.txt >diffc.expect &&
+	diffc_verify
+'
+
+test_done