+test_expect_success 'trivial merge with custom strategy' '
+ git reset --hard c1 &&
+
+ git rev-parse c1 >head.old &&
+ git rev-parse c3 >second-parent.expected &&
+ git rev-parse c3^{tree} >tree.expected &&
+ git merge -s theirs c3 &&
+
+ git rev-parse HEAD >head &&
+ git rev-parse HEAD^1 >first-parent &&
+ git rev-parse HEAD^2 >second-parent &&
+ git rev-parse HEAD^{tree} >tree &&
+ git update-index --refresh &&
+ git diff --exit-code &&
+ git diff --exit-code c3 HEAD &&
+ git diff --exit-code c3 &&
+
+ ! test_cmp head.old head &&
+ test_cmp head.old first-parent &&
+ test_cmp second-parent.expected second-parent &&
+ test_cmp tree.expected tree &&
+ test -f c0.c &&
+ ! test -e c1.c &&
+ test -f c3.c
+'
+