rebase: improve error message when upstream argument is missing

diff --git a/t/t4041-diff-submodule.sh b/t/t4041-diff-submodule.sh
index 11b19972ca89f20faaa35b8a2c9fcd7f97181f78..019acb926d6765bf24e1dfe4bea2a9dba28ca797 100755 (executable)
--- a/t/t4041-diff-submodule.sh
+++ b/t/t4041-diff-submodule.sh
@@ -329,4 +329,19 @@ index 0000000..$head7
 EOF
 "
 
+test_expect_success 'setup .git file for sm2' '
+       (cd sm2 &&
+        REAL="$(pwd)/../.real" &&
+        mv .git "$REAL"
+        echo "gitdir: $REAL" >.git)
+'
+
+test_expect_success 'diff --submodule with .git file' '
+       git diff --submodule HEAD^ >actual &&
+       diff actual - <<-EOF
+Submodule sm1 $head6...0000000 (submodule deleted)
+Submodule sm2 0000000...$head7 (new submodule)
+EOF
+'
+
 test_done