add tests for checkout -b

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/t2018-checkout-branch.sh b/t/t2018-checkout-branch.sh
new file mode 100755 (executable)
index 0000000..3c13065
--- /dev/null
+++ b/t/t2018-checkout-branch.sh
@@ -0,0 +1,121 @@
+#!/bin/sh
+
+test_description='checkout '
+
+. ./test-lib.sh
+
+# Arguments: <branch> <sha> [<checkout options>]
+#
+# Runs "git checkout" to switch to <branch>, testing that
+#
+#   1) we are on the specified branch, <branch>;
+#   2) HEAD is <sha>; if <sha> is not specified, the old HEAD is used.
+#
+# If <checkout options> is not specified, "git checkout" is run with -b.
+do_checkout() {
+       exp_branch=$1 &&
+       exp_ref="refs/heads/$exp_branch" &&
+
+       # if <sha> is not specified, use HEAD.
+       exp_sha=${2:-$(git rev-parse --verify HEAD)} &&
+
+       # default options for git checkout: -b
+       if [ -z "$3" ]; then
+               opts="-b"
+       else
+               opts="$3"
+       fi
+
+       git checkout $opts $exp_branch $exp_sha &&
+
+       test $exp_ref = $(git rev-parse --symbolic-full-name HEAD) &&
+       test $exp_sha = $(git rev-parse --verify HEAD)
+}
+
+test_dirty_unmergeable() {
+       ! git diff --exit-code >/dev/null
+}
+
+setup_dirty_unmergeable() {
+       echo >>file1 change2
+}
+
+test_dirty_mergeable() {
+       ! git diff --cached --exit-code >/dev/null
+}
+
+setup_dirty_mergeable() {
+       echo >file2 file2 &&
+       git add file2
+}
+
+test_expect_success 'setup' '
+       test_commit initial file1 &&
+       HEAD1=$(git rev-parse --verify HEAD) &&
+
+       test_commit change1 file1 &&
+       HEAD2=$(git rev-parse --verify HEAD) &&
+
+       git branch -m branch1
+'
+
+test_expect_success 'checkout -b to a new branch, set to HEAD' '
+       do_checkout branch2
+'
+
+test_expect_success 'checkout -b to a new branch, set to an explicit ref' '
+       git checkout branch1 &&
+       git branch -D branch2 &&
+
+       do_checkout branch2 $HEAD1
+'
+
+test_expect_success 'checkout -b to a new branch with unmergeable changes fails' '
+       git checkout branch1 &&
+
+       # clean up from previous test
+       git branch -D branch2 &&
+
+       setup_dirty_unmergeable &&
+       test_must_fail do_checkout branch2 $HEAD1 &&
+       test_dirty_unmergeable
+'
+
+test_expect_success 'checkout -f -b to a new branch with unmergeable changes discards changes' '
+       # still dirty and on branch1
+       do_checkout branch2 $HEAD1 "-f -b" &&
+       test_must_fail test_dirty_unmergeable
+'
+
+test_expect_success 'checkout -b to a new branch preserves mergeable changes' '
+       git checkout branch1 &&
+
+       # clean up from previous test
+       git branch -D branch2 &&
+
+       setup_dirty_mergeable &&
+       do_checkout branch2 $HEAD1 &&
+       test_dirty_mergeable
+'
+
+test_expect_success 'checkout -f -b to a new branch with mergeable changes discards changes' '
+       # clean up from previous test
+       git reset --hard &&
+
+       git checkout branch1 &&
+
+       # clean up from previous test
+       git branch -D branch2 &&
+
+       setup_dirty_mergeable &&
+       do_checkout branch2 $HEAD1 "-f -b" &&
+       test_must_fail test_dirty_mergeable
+'
+
+test_expect_success 'checkout -b to an existing branch fails' '
+       git reset --hard HEAD &&
+
+       test_must_fail do_checkout branch2 $HEAD2
+'
+
+test_done