Merge branch 'em/checkout-orphan'

* em/checkout-orphan:
  git checkout: create unparented branch by --orphan

t/t2017-checkout-orphan.sh

@@ -0,0 +1,90 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Erick Mattos
+#
+
+test_description='git checkout --orphan
+
+Main Tests for --orphan functionality.'
+
+. ./test-lib.sh
+
+TEST_FILE=foo
+
+test_expect_success 'Setup' '
+	echo "Initial" >"$TEST_FILE" &&
+	git add "$TEST_FILE" &&
+	git commit -m "First Commit"
+	test_tick &&
+	echo "State 1" >>"$TEST_FILE" &&
+	git add "$TEST_FILE" &&
+	test_tick &&
+	git commit -m "Second Commit"
+'
+
+test_expect_success '--orphan creates a new orphan branch from HEAD' '
+	git checkout --orphan alpha &&
+	test_must_fail git rev-parse --verify HEAD &&
+	test "refs/heads/alpha" = "$(git symbolic-ref HEAD)" &&
+	test_tick &&
+	git commit -m "Third Commit" &&
+	test_must_fail git rev-parse --verify HEAD^ &&
+	git diff-tree --quiet master alpha
+'
+
+test_expect_success '--orphan creates a new orphan branch from <start_point>' '
+	git checkout master &&
+	git checkout --orphan beta master^ &&
+	test_must_fail git rev-parse --verify HEAD &&
+	test "refs/heads/beta" = "$(git symbolic-ref HEAD)" &&
+	test_tick &&
+	git commit -m "Fourth Commit" &&
+	test_must_fail git rev-parse --verify HEAD^ &&
+	git diff-tree --quiet master^ beta
+'
+
+test_expect_success '--orphan must be rejected with -b' '
+	git checkout master &&
+	test_must_fail git checkout --orphan new -b newer &&
+	test refs/heads/master = "$(git symbolic-ref HEAD)"
+'
+
+test_expect_success '--orphan is rejected with an existing name' '
+	git checkout master &&
+	test_must_fail git checkout --orphan master &&
+	test refs/heads/master = "$(git symbolic-ref HEAD)"
+'
+
+test_expect_success '--orphan refuses to switch if a merge is needed' '
+	git checkout master &&
+	git reset --hard &&
+	echo local >>"$TEST_FILE" &&
+	cat "$TEST_FILE" >"$TEST_FILE.saved" &&
+	test_must_fail git checkout --orphan gamma master^ &&
+	test refs/heads/master = "$(git symbolic-ref HEAD)" &&
+	test_cmp "$TEST_FILE" "$TEST_FILE.saved" &&
+	git diff-index --quiet --cached HEAD &&
+	git reset --hard
+'
+
+test_expect_success '--orphan does not mix well with -t' '
+	git checkout master &&
+	test_must_fail git checkout -t master --orphan gamma &&
+	test refs/heads/master = "$(git symbolic-ref HEAD)"
+'
+
+test_expect_success '--orphan ignores branch.autosetupmerge' '
+	git checkout -f master &&
+	git config branch.autosetupmerge always &&
+	git checkout --orphan delta &&
+	test -z "$(git config branch.delta.merge)" &&
+	test refs/heads/delta = "$(git symbolic-ref HEAD)" &&
+	test_must_fail git rev-parse --verify HEAD^
+'
+
+test_expect_success '--orphan does not mix well with -l' '
+	git checkout -f master &&
+	test_must_fail git checkout -l --orphan gamma
+'
+
+test_done