[StGit PATCH 09/13] Clear up the semantics of Series.new_patch

["David Kågedal" <davidk@lysator.liu.se>]

This patch adds a number of assertions to document and verify the
complex restrictions of the input parameters to the Series.new_patch
function. It also adds the requirement that 'before_existing' and
'commit' cannot be true at the same time when calling it, instead of
updating 'commit' inside the function.

Signed-off-by: David Kågedal <davidk@lysator.liu.se>
---

 stgit/commands/uncommit.py |    1 +
 stgit/stack.py             |   14 ++++++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)


diff --git a/stgit/commands/uncommit.py b/stgit/commands/uncommit.py
index 3cf2f0a..0cd0fb0 100644
--- a/stgit/commands/uncommit.py
+++ b/stgit/commands/uncommit.py
@@ -129,6 +129,7 @@ def func(parser, options, args):
                      name_email_date(commit.get_author())
         crt_series.new_patch(patchname,
                              can_edit = False, before_existing = True,
+                             commit = False,
                              top = commit_id, bottom = parent,
                              message = commit.get_log(),
                              author_name = author_name,
diff --git a/stgit/stack.py b/stgit/stack.py
index fd19a82..733a241 100644
--- a/stgit/stack.py
+++ b/stgit/stack.py
@@ -833,9 +833,16 @@ class Series(PatchSet):
                   author_name = None, author_email = None, author_date = None,
                   committer_name = None, committer_email = None,
                   before_existing = False):
-        """Creates a new patch
+        """Creates a new patch, either pointing to an existing commit object,
+        or by creating a new commit object.
         """
 
+        assert commit or (top and bottom)
+        assert not before_existing or (top and bottom)
+        assert not (commit and before_existing)
+        assert (top and bottom) or (not top and not bottom)
+        assert not top or (bottom == git.get_commit(top).get_parent())
+
         if name != None:
             self.__patch_name_valid(name)
             if self.patch_exists(name):
@@ -873,9 +880,6 @@ class Series(PatchSet):
 
         if before_existing:
             insert_string(self.__applied_file, patch.get_name())
-            # no need to commit anything as the object is already
-            # present (mainly used by 'uncommit')
-            commit = False
         elif unapplied:
             patches = [patch.get_name()] + self.get_unapplied()
             write_strings(self.__unapplied_file, patches)
@@ -900,6 +904,8 @@ class Series(PatchSet):
                                    committer_email = committer_email)
             # set the patch top to the new commit
             patch.set_top(commit_id)
+        else:
+            assert top != bottom
 
         self.log_patch(patch, 'new')