morph branch: Fail if branch already exists in the system repo

4 files changed, 53 insertions, 0 deletions

diff --git a/morphlib/git.py b/morphlib/git.py
index 0a4b01f4..f5722ebe 100644
--- a/morphlib/git.py
+++ b/morphlib/git.py
@@ -150,6 +150,14 @@ def checkout_ref(runcmd, gitdir, ref):
     '''Checks out a specific ref/SHA1 in a git working tree.'''
     runcmd(['git', 'checkout', ref], cwd=gitdir)
 
+def ref_exists(runcmd, gitdir, ref):
+    '''Check if specific ref exists locally or in a remote.'''
+    try:
+        runcmd(['git', 'show-ref', '--quiet', ref], cwd=gitdir)
+    except cliapp.AppException:
+        return False
+    return True
+
 def reset_workdir(runcmd, gitdir):
     '''Removes any differences between the current commit '''
     '''and the status of the working directory'''
diff --git a/morphlib/plugins/branch_and_merge_plugin.py b/morphlib/plugins/branch_and_merge_plugin.py
index 714f2838..cb55ade5 100644
--- a/morphlib/plugins/branch_and_merge_plugin.py
+++ b/morphlib/plugins/branch_and_merge_plugin.py
@@ -408,6 +408,11 @@ class BranchAndMergePlugin(cliapp.Plugin):
             repo_dir = os.path.join(branch_dir, self.convert_uri_to_path(repo))
             self.clone_to_directory(repo_dir, repo, commit)
 
+            # Check if branch already exists locally or in a remote
+            if morphlib.git.ref_exists(self.app.runcmd, repo_dir, new_branch):
+                raise cliapp.AppException('branch %s already exists in '
+                                          'repository %s' % (new_branch, repo))
+
             # Create a new branch in the local morphs repository.
             self.app.runcmd(['git', 'checkout', '-b', new_branch, commit],
                             cwd=repo_dir)
diff --git a/tests.branching/branch-fails-if-branch-exists.script b/tests.branching/branch-fails-if-branch-exists.script
new file mode 100755
index 00000000..c9a18633
--- /dev/null
+++ b/tests.branching/branch-fails-if-branch-exists.script
@@ -0,0 +1,39 @@
+#!/bin/sh
+# Copyright (C) 2012  Codethink Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+# Make sure "morph branch" fails if the system branch already exists in the
+# branch root (morphologies repo).
+
+set -eu
+
+cd "$DATADIR/morphs"
+git checkout --quiet -b baserock/existing-branch
+
+cd "$DATADIR/workspace"
+"$SRCDIR/scripts/test-morph" init
+
+# We create a valid branch inside the same prefix first so we can check it
+# doesn't get caught up in the deletion of the invalid branch directory
+
+"$SRCDIR/scripts/test-morph" branch baserock:morphs baserock/new-branch
+
+[ -d "$DATADIR/workspace/baserock/new-branch" ]
+
+"$SRCDIR/scripts/test-morph" branch baserock:morphs \
+    baserock/existing-branch || true
+
+[ -d "$DATADIR/workspace/baserock/new-branch" ]
+[ ! -d "$DATADIR/workspace/baserock/existing-branch" ]
diff --git a/tests.branching/branch-fails-if-branch-exists.stderr b/tests.branching/branch-fails-if-branch-exists.stderr
new file mode 100644
index 00000000..c2ae2d9e
--- /dev/null
+++ b/tests.branching/branch-fails-if-branch-exists.stderr
@@ -0,0 +1 @@
+ERROR: branch baserock/existing-branch already exists in repository baserock:morphs