dch: Create changelog if missing

Closes: #669171
Thanks: Daniel Dehennin for the groundwork on this

3 files changed, 33 insertions, 2 deletions

diff --git a/docs/manpages/gbp-dch.xml b/docs/manpages/gbp-dch.xml
index 24773b15..e85cb777 100644
--- a/docs/manpages/gbp-dch.xml
+++ b/docs/manpages/gbp-dch.xml
@@ -137,6 +137,10 @@
       or upstream's tagging pattern (when using upstream's git
       directly).
     </para>
+    <para>
+      If not changelog exists yet it is created and the version number
+      is derived from the last upstream tag if found.
+    </para>
   </refsect1>
   <refsect1>
     <title>OPTIONS</title>
diff --git a/gbp/scripts/dch.py b/gbp/scripts/dch.py
index 0d66a801..a086464c 100644
--- a/gbp/scripts/dch.py
+++ b/gbp/scripts/dch.py
@@ -304,6 +304,26 @@ def changelog_commit_msg(options, version):
     return options.commit_msg % dict(version=version)
 
 
+def create_changelog(repo, source, options):
+    try:
+        name = source.control.name
+    except DebianSourceError:
+        raise GbpError("Did not find debian/changelog or debian/source. Is this a Debian package?")
+    version = guess_version_from_upstream(repo, options.upstream_tag,
+                                          options.upstream_branch, None)
+    return ChangeLog.create(name, version)
+
+
+def maybe_create_changelog(repo, source, options):
+    """
+    Get the changelog or create a new one if it does not exist yet
+    """
+    try:
+        return source.changelog
+    except DebianSourceError:
+        return create_changelog(repo, source, options)
+
+
 def build_parser(name):
     try:
         parser = GbpOptionParserDebian(command=os.path.basename(name),
@@ -452,7 +472,7 @@ def main(argv):
             raise GbpError("Use --ignore-branch to ignore or --debian-branch to set the branch name.")
 
         source = DebianSource('.')
-        cp = source.changelog
+        cp = maybe_create_changelog(repo, source, options)
 
         if options.since:
             since = options.since
diff --git a/tests/11_test_dch_main.py b/tests/11_test_dch_main.py
index bebb1e4c..d9023c3c 100644
--- a/tests/11_test_dch_main.py
+++ b/tests/11_test_dch_main.py
@@ -404,4 +404,11 @@ class TestScriptDch(DebianGitTestRepo):
 
     def test_dch_subdir(self):
         os.chdir('debian/')
-        self.run_dch()
+        lines = self.run_dch()
+        self.assertEqual("test-package (1.0-1) UNRELEASED; urgency=%s\n" % default_urgency, lines[0])
+        self.assertIn("""  * added debian/control\n""", lines)
+
+    def test_dch_create_changelog(self):
+        os.unlink('debian/changelog')
+        lines = self.run_dch()
+        self.assertEqual("test-package (1.0-1) UNRELEASED; urgency=%s\n" % default_urgency, lines[0])