--- /dev/null
+#!/bin/sh
+
+test_description='git-merge
+
+Do not overwrite changes.'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+ echo c0 > c0.c &&
+ git add c0.c &&
+ git commit -m c0 &&
+ git tag c0 &&
+ echo c1 > c1.c &&
+ git add c1.c &&
+ git commit -m c1 &&
+ git tag c1 &&
+ git reset --hard c0 &&
+ echo c2 > c2.c &&
+ git add c2.c &&
+ git commit -m c2 &&
+ git tag c2 &&
+ git reset --hard c1 &&
+ echo "c1 a" > c1.c &&
+ git add c1.c &&
+ git commit -m "c1 a" &&
+ git tag c1a &&
+ echo "VERY IMPORTANT CHANGES" > important
+'
+
+test_expect_success 'will not overwrite untracked file' '
+ git reset --hard c1 &&
+ cat important > c2.c &&
+ ! git merge c2 &&
+ test_cmp important c2.c
+'
+
+test_expect_success 'will not overwrite new file' '
+ git reset --hard c1 &&
+ cat important > c2.c &&
+ git add c2.c &&
+ ! git merge c2 &&
+ test_cmp important c2.c
+'
+
+test_expect_success 'will not overwrite staged changes' '
+ git reset --hard c1 &&
+ cat important > c2.c &&
+ git add c2.c &&
+ rm c2.c &&
+ ! git merge c2 &&
+ git checkout c2.c &&
+ test_cmp important c2.c
+'
+
+test_expect_failure 'will not overwrite removed file' '
+ git reset --hard c1 &&
+ git rm c1.c &&
+ git commit -m "rm c1.c" &&
+ cat important > c1.c &&
+ ! git merge c1a &&
+ test_cmp important c1.c
+'
+
+test_expect_success 'will not overwrite re-added file' '
+ git reset --hard c1 &&
+ git rm c1.c &&
+ git commit -m "rm c1.c" &&
+ cat important > c1.c &&
+ git add c1.c &&
+ ! git merge c1a &&
+ test_cmp important c1.c
+'
+
+test_expect_success 'will not overwrite removed file with staged changes' '
+ git reset --hard c1 &&
+ git rm c1.c &&
+ git commit -m "rm c1.c" &&
+ cat important > c1.c &&
+ git add c1.c &&
+ rm c1.c &&
+ ! git merge c1a &&
+ git checkout c1.c &&
+ test_cmp important c1.c
+'
+
+test_done