[PATCHv2 1/8] t2024: Add tests verifying current DWIM behavior of 'git checkout <branch>'

@@ -0,0 +1,66 @@
+#!/bin/sh
+
+test_description='checkout <branch>
+
+Ensures that checkout on an unborn branch does what the user expects'
+
+. ./test-lib.sh
+
+# Arguments: <branch> <remote> <remote-tracking>
+#
+# Verify that we have checked out <branch>, and that it is at the same
+# commit as <remote-tracking>, and that has appropriate tracking config
+# setup against <remote>
+test_tracking_branch() {
+	branch=$1 &&
+	remote=$2 &&
+	remote_track=$3 &&
+	test "refs/heads/$branch" = "$(git rev-parse --symbolic-full-name HEAD)" &&
+	test "$(git rev-parse --verify HEAD)" = "$(git rev-parse --verify "$remote_track")" &&
+	test "$remote" = "$(git config "branch.$branch.remote")" &&
+	test "refs/heads/$branch" = "$(git config "branch.$branch.merge")"
+}
+
+test_expect_success 'setup' '
+	(git init repo_a &&
+	 cd repo_a &&
+	 test_commit a_master &&
+	 git checkout -b foo &&
+	 test_commit a_foo &&
+	 git checkout -b bar &&
+	 test_commit a_bar
+	) &&
+	(git init repo_b &&
+	 cd repo_b &&
+	 test_commit b_master &&
+	 git checkout -b foo &&
+	 test_commit b_foo &&
+	 git checkout -b baz &&
+	 test_commit b_baz
+	) &&
+	git remote add repo_a repo_a &&
+	git remote add repo_b repo_b &&
+	git config remote.repo_b.fetch \
+		"+refs/heads/*:refs/remotes/other_b/*" &&
+	git fetch --all
+'
+
+test_expect_success 'checkout of non-existing branch fails' '
+	test_must_fail git checkout xyzzy
+'
+
+test_expect_success 'checkout of branch from multiple remotes fails' '
+	test_must_fail git checkout foo
+'
+
+test_expect_success 'checkout of branch from a single remote succeeds #1' '
+	git checkout bar &&
+	test_tracking_branch bar repo_a refs/remotes/repo_a/bar
+'
+
+test_expect_success 'checkout of branch from a single remote succeeds #2' '
+	git checkout baz &&
+	test_tracking_branch baz repo_b refs/remotes/other_b/baz
+'
+
+test_done