[RFC/PATCH 4/4] apply: add t4137 for submodule updates

Test that the apply command updates the work tree as expected for the
'--index' and the '--3way' options (for submodule changes which don't
result in conflicts).

Signed-off-by: Jens Lehmann <redacted>
---

And this shows how to use the new framework when more than a single command
is needed to switch to a new work tree.

 t/t4137-apply-submodule.sh | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100755 t/t4137-apply-submodule.sh

diff --git a/t/t4137-apply-submodule.sh b/t/t4137-apply-submodule.sh
new file mode 100755
index 0000000..f0a0500
--- /dev/null
+++ b/t/t4137-apply-submodule.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+test_description='git am handling submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+apply_index () {
+    git diff --ignore-submodules=dirty "..$1" | git apply --index -
+}
+
+test_submodule_switch "apply_index"
+
+apply_3way () {
+    git diff --ignore-submodules=dirty "..$1" | git apply --3way -
+}
+
+test_submodule_switch "apply_3way"
+
+test_done

-- 
1.9.1.327.g3d8d896