Merge branch 'jl/submodule-tests'

* jl/submodule-tests:
  revert: add t3513 for submodule updates
  stash: add t3906 for submodule updates
  am: add t4255 for submodule updates
  cherry-pick: add t3512 for submodule updates
  pull: add t5572 for submodule updates
  rebase: add t3426 for submodule updates
  merge: add t7613 for submodule updates
  bisect: add t6041 for submodule updates
  reset: add t7112 for submodule updates
  read-tree: add t1013 for submodule updates
  apply: add t4137 for submodule updates
  checkout: call the new submodule update test framework
  submodules: add the lib-submodule-update.sh test library
  test-lib: add test_dir_is_empty()

t/t1013-read-tree-submodule.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+test_description='read-tree can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+test_submodule_switch "git read-tree -u -m"
+
+test_submodule_forced_switch "git read-tree -u --reset"
+
+test_done

t/t2013-checkout-submodule.sh

@@ -3,6 +3,7 @@
 test_description='checkout can handle submodules'
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
 
 test_expect_success 'setup' '
 	mkdir submodule &&
@@ -62,4 +63,8 @@ test_expect_success '"checkout <submodule>" honors submodule.*.ignore from .git/
 	! test -s actual
 '
 
+test_submodule_switch "git checkout"
+
+test_submodule_forced_switch "git checkout -f"
+
 test_done

t/t3426-rebase-submodule.sh

@@ -0,0 +1,46 @@
+#!/bin/sh
+
+test_description='rebase can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+. "$TEST_DIRECTORY"/lib-rebase.sh
+
+git_rebase () {
+	git status -su >expect &&
+	ls -1pR * >>expect &&
+	git checkout -b ours HEAD &&
+	echo x >>file1 &&
+	git add file1 &&
+	git commit -m add_x &&
+	git revert HEAD &&
+	git status -su >actual &&
+	ls -1pR * >>actual &&
+	test_cmp expect actual &&
+	git rebase "$1"
+}
+
+test_submodule_switch "git_rebase"
+
+git_rebase_interactive () {
+	git status -su >expect &&
+	ls -1pR * >>expect &&
+	git checkout -b ours HEAD &&
+	echo x >>file1 &&
+	git add file1 &&
+	git commit -m add_x &&
+	git revert HEAD &&
+	git status -su >actual &&
+	ls -1pR * >>actual &&
+	test_cmp expect actual &&
+	set_fake_editor &&
+	echo "fake-editor.sh" >.git/info/exclude &&
+	git rebase -i "$1"
+}
+
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+# The real reason "replace directory with submodule" fails is because a
+# directory "sub1" exists, but we reuse the suppression added for merge here
+test_submodule_switch "git_rebase_interactive"
+
+test_done

t/t3512-cherry-pick-submodule.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+test_description='cherry-pick can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT=1
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+KNOWN_FAILURE_NOFF_MERGE_ATTEMPTS_TO_MERGE_REMOVED_SUBMODULE_FILES=1
+test_submodule_switch "git cherry-pick"
+
+test_done

t/t3513-revert-submodule.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+test_description='revert can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+# Create a revert that moves from HEAD (including any test modifications to
+# the work tree) to $1 by first checking out $1 and reverting it. Reverting
+# the revert is the transition we test for. We tar the current work tree
+# first so we can restore the work tree test setup after doing the checkout
+# and revert.  We test here that the restored work tree content is identical
+# to that at the beginning. The last revert is then tested by the framework.
+git_revert () {
+	git status -su >expect &&
+	ls -1pR * >>expect &&
+	tar czf "$TRASH_DIRECTORY/tmp.tgz" * &&
+	git checkout "$1" &&
+	git revert HEAD &&
+	rm -rf * &&
+	tar xzf "$TRASH_DIRECTORY/tmp.tgz" &&
+	git status -su >actual &&
+	ls -1pR * >>actual &&
+	test_cmp expect actual &&
+	git revert HEAD
+}
+
+KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT=1
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+test_submodule_switch "git_revert"
+
+test_done

t/t3906-stash-submodule.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+test_description='stash apply can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+git_stash () {
+	git status -su >expect &&
+	ls -1pR * >>expect &&
+	git read-tree -u -m "$1" &&
+	git stash &&
+	git status -su >actual &&
+	ls -1pR * >>actual &&
+	test_cmp expect actual &&
+	git stash apply
+}
+
+KNOWN_FAILURE_STASH_DOES_IGNORE_SUBMODULE_CHANGES=1
+KNOWN_FAILURE_CHERRY_PICK_SEES_EMPTY_COMMIT=1
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+test_submodule_switch "git_stash"
+
+test_done

t/t4137-apply-submodule.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+test_description='git apply 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

t/t4255-am-submodule.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+test_description='git am handling submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+am () {
+	git format-patch --stdout --ignore-submodules=dirty "..$1" | git am -
+}
+
+test_submodule_switch "am"
+
+am_3way () {
+	git format-patch --stdout --ignore-submodules=dirty "..$1" | git am --3way -
+}
+
+KNOWN_FAILURE_NOFF_MERGE_ATTEMPTS_TO_MERGE_REMOVED_SUBMODULE_FILES=1
+test_submodule_switch "am_3way"
+
+test_done

t/t5572-pull-submodule.sh

@@ -0,0 +1,45 @@
+#!/bin/sh
+
+test_description='pull can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+reset_branch_to_HEAD () {
+	git branch -D "$1" &&
+	git checkout -b "$1" HEAD &&
+	git branch --set-upstream-to="origin/$1" "$1"
+}
+
+git_pull () {
+	reset_branch_to_HEAD "$1" &&
+	git pull
+}
+
+# pulls without conflicts
+test_submodule_switch "git_pull"
+
+git_pull_ff () {
+	reset_branch_to_HEAD "$1" &&
+	git pull --ff
+}
+
+test_submodule_switch "git_pull_ff"
+
+git_pull_ff_only () {
+	reset_branch_to_HEAD "$1" &&
+	git pull --ff-only
+}
+
+test_submodule_switch "git_pull_ff_only"
+
+git_pull_noff () {
+	reset_branch_to_HEAD "$1" &&
+	git pull --no-ff
+}
+
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+KNOWN_FAILURE_NOFF_MERGE_ATTEMPTS_TO_MERGE_REMOVED_SUBMODULE_FILES=1
+test_submodule_switch "git_pull_noff"
+
+test_done

t/t6041-bisect-submodule.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+test_description='bisect can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+git_bisect () {
+	git status -su >expect &&
+	ls -1pR * >>expect &&
+	tar czf "$TRASH_DIRECTORY/tmp.tgz" * &&
+	GOOD=$(git rev-parse --verify HEAD) &&
+	git checkout "$1" &&
+	echo "foo" >bar &&
+	git add bar &&
+	git commit -m "bisect bad" &&
+	BAD=$(git rev-parse --verify HEAD) &&
+	git reset --hard HEAD^^ &&
+	git submodule update &&
+	git bisect start &&
+	git bisect good $GOOD &&
+	rm -rf * &&
+	tar xzf "$TRASH_DIRECTORY/tmp.tgz" &&
+	git status -su >actual &&
+	ls -1pR * >>actual &&
+	test_cmp expect actual &&
+	git bisect bad $BAD
+}
+
+test_submodule_switch "git_bisect"
+
+test_done

t/t7112-reset-submodule.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+test_description='reset can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+test_submodule_switch "git reset --keep"
+
+test_submodule_switch "git reset --merge"
+
+test_submodule_forced_switch "git reset --hard"
+
+test_done

t/t7613-merge-submodule.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+test_description='merge can handle submodules'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-submodule-update.sh
+
+# merges without conflicts
+test_submodule_switch "git merge"
+
+test_submodule_switch "git merge --ff"
+
+test_submodule_switch "git merge --ff-only"
+
+KNOWN_FAILURE_NOFF_MERGE_DOESNT_CREATE_EMPTY_SUBMODULE_DIR=1
+KNOWN_FAILURE_NOFF_MERGE_ATTEMPTS_TO_MERGE_REMOVED_SUBMODULE_FILES=1
+test_submodule_switch "git merge --no-ff"
+
+test_done

t/test-lib-functions.sh

@@ -489,6 +489,17 @@ test_path_is_dir () {
 	fi
 }
 
+# Check if the directory exists and is empty as expected, barf otherwise.
+test_dir_is_empty () {
+	test_path_is_dir "$1" &&
+	if test -n "$(ls -a1 "$1" | egrep -v '^\.\.?$')"
+	then
+		echo "Directory '$1' is not empty, it contains:"
+		ls -la "$1"
+		return 1
+	fi
+}
+
 test_path_is_missing () {
 	if [ -e "$1" ]
 	then