Add "morph merge" subcommand

This is highly simplisitic, and it's going to be highly painful
to use, but it does the very basics of what we need, I think.

4 files changed, 69 insertions, 2 deletions

diff --git a/doc/branching-merging-systems.mdwn b/doc/branching-merging-systems.mdwn
index 6fe4d590..3e781b5a 100644
--- a/doc/branching-merging-systems.mdwn
+++ b/doc/branching-merging-systems.mdwn
@@ -295,8 +295,9 @@ Usage:
 
     morph merge BRANCH
 
-This needs to be run inside a system branch directory, and `BRANCH`
-must be another system branch checked out in the morph mine.
+This needs to be run inside a system branch directory's `morphs`
+repository, and `BRANCH` must be another system branch checked out 
+in the morph mine.
 
 * In each git repository modified by the `BRANCH` system branch, 
   run `git merge --no-commit BRANCH`, then undo any changes to 
diff --git a/morph b/morph
index 5b632a0e..5f278cb4 100755
--- a/morph
+++ b/morph
@@ -469,7 +469,24 @@ class Morph(cliapp.Application):
         self._clone_to_directory(new_repo, repo, ref)
         self.runcmd(['git', 'checkout', '-b', system_branch, ref],
                     cwd=new_repo)
+
+    def cmd_merge(self, args):
+        '''Merge specified repositories from another system branch.'''
+        
+        if len(args) == 0:
+            raise cliapp.AppException('morph merge must get a branch name '
+                                        'and some repo names as arguments')
+
+        other_branch = args[0]
+        mine = self._deduce_mine_directory()
+        this_branch = self._deduce_system_branch()
         
+        for repo in args[1:]:
+            basename = os.path.basename(repo)
+            pull_from = os.path.join(mine, other_branch, basename)
+            repo_dir = os.path.join(mine, this_branch, basename)
+            self.runcmd(['git', 'pull', pull_from], cwd=repo_dir)
+
     def msg(self, msg):
         '''Show a message to the user about what is going on.'''
         logging.debug(msg)
diff --git a/tests.branching/merge-explicitly-named-repos.script b/tests.branching/merge-explicitly-named-repos.script
new file mode 100755
index 00000000..de6ecebc
--- /dev/null
+++ b/tests.branching/merge-explicitly-named-repos.script
@@ -0,0 +1,48 @@
+#!/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.
+
+
+# Check that "morph merge" merges explicitly named repositories.
+
+
+set -eu
+
+
+# Create system branch.
+cd "$DATADIR/mine"
+"$SRCDIR/scripts/test-morph" init
+"$SRCDIR/scripts/test-morph" branch newbranch
+
+# Make a change to a chunk.
+cd newbranch/morphs
+"$SRCDIR/scripts/test-morph" edit hello master
+cd ../hello
+touch newfile.txt
+git add newfile.txt
+git commit -m foo --quiet
+
+# Merge changes to a new system branch.
+cd "$DATADIR/mine"
+"$SRCDIR/scripts/test-morph" branch otherbranch
+cd otherbranch/morphs
+"$SRCDIR/scripts/test-morph" edit hello master
+"$SRCDIR/scripts/test-morph" merge newbranch hello
+
+# Check results.
+cd ../hello
+git status --short # make sure all changes are committed
+ls newfile.txt # make sure the new file is there
+
diff --git a/tests.branching/merge-explicitly-named-repos.stdout b/tests.branching/merge-explicitly-named-repos.stdout
new file mode 100644
index 00000000..cd2122c4
--- /dev/null
+++ b/tests.branching/merge-explicitly-named-repos.stdout
@@ -0,0 +1 @@
+newfile.txt