[PATCH 6 of 6 RFC] destutil: choose non-closed branch head as default update destination (BC)

[FUJIWARA Katsunori]

# HG changeset patch
# User FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
# Date 1456322433 -32400
#      Wed Feb 24 23:00:33 2016 +0900
# Node ID ae5d291a6dcb96683eae3c4e33575297fa113fbb
# Parent  1f9b3d38e380b018cbe10ed1acee882c014e3763
destutil: choose non-closed branch head as default update destination (BC)

Before this patch, destupdate() returns the tipmost (descendant)
branch head regardless of closed or not. But updating to closed branch
head isn't reasonable for ordinary workflow, because:

  - "hg heads" doesn't show closed heads (= updated parent itself) by
    default

  - subsequent committing on it re-opens closed branch

    even if inactivation of closed head is needed, update destination
    isn't it, because it should be merged into to another branch in
    such case.

This patch chooses non-closed branch head as default update
destination.

This patch changes not only normal lookup code path, but also "no
default branch" code path, for consistency.

If no appropriate default update destination is found, destupdate()
returns '.' as destination to work as no-op at updating. 'None' isn't
reasonable for this purpose, because:

  - repo[node] returns useless rev/node if node=None
  - merge.update() re-invokes destupdate() for None destination

diff --git a/mercurial/destutil.py b/mercurial/destutil.py
--- a/mercurial/destutil.py
+++ b/mercurial/destutil.py
@@ -93,14 +93,15 @@ def _destupdatebranch(repo, clean, check
     movemark = node = None
     currentbranch = wc.branch()
     if currentbranch in repo.branchmap():
-        heads = repo.branchheads(currentbranch, closed=True)
+        heads = repo.branchheads(currentbranch)
         if heads:
             node = repo.revs('max(.::(%ln))', heads).first()
         if bookmarks.isactivewdirparent(repo):
             movemark = repo['.'].node()
     else:
         if currentbranch == 'default': # no default branch!
-            node = repo.lookup('tip') # update to tip
+            # update to the tipmost non-closed branch head
+            node = repo.revs('max(head() and not closed())').first()
         else:
             raise error.Abort(_("branch %s not found") % currentbranch)
     return node, movemark, None
@@ -130,6 +131,11 @@ def destupdate(repo, clean=False, check=
         node, movemark, activemark = destupdatestepmap[step](repo, clean, check)
         if node is not None:
             break
+    else:
+        # udate to current parent (= no-op), because no appropriate
+        # default destination is found
+        node = '.'
+
     rev = repo[node].rev()
 
     _destupdatevalidate(repo, rev, clean, check)
@@ -366,6 +372,16 @@ def _statusotherbranchheads(ui, repo):
         if otherheads:
             ui.status(_('%i other heads for branch "%s"\n') %
                       (len(otherheads), currentbranch))
+    elif len(repo): # omit redundant message in empty repository
+        if not heads:
+            if currentbranch not in repo.branchmap():
+                # this is "update to the tipmost non-closed branch head" case
+                ui.status(_('all branches are closed\n'))
+            else:
+                ui.status(_('all heads of branch "%s" are closed\n') %
+                          currentbranch)
+        elif not len(repo.revs('parents()::(%ln)', heads)):
+            ui.status(_('all descendant branch heads are closed\n'))
 
 def statusotherdests(ui, repo):
     """Print message about other head"""
diff --git a/tests/test-update-branches.t b/tests/test-update-branches.t
--- a/tests/test-update-branches.t
+++ b/tests/test-update-branches.t
@@ -196,6 +196,24 @@ if on the closed branch head:
   1 other heads for branch "default"
   parent=6
 
+if only one descendant non-closed branch head exists:
+- update to it, even if its revision is less than closed one
+- "N other heads for ...." message isn't displayed
+
+  $ norevtest "non-closed 2 should be chosen" clean 1
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  parent=2
+
+if all descendant branch heads are closed:
+- updating is no-op
+- "N other heads for ...." message isn't displayed
+- "all descendant branch ...." is displayed
+
+  $ norevtest "all descendant branch heads are closed" clean 3
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  all descendant branch heads are closed
+  parent=3
+
 Test updating if all branch heads are closed
 
 if on the closed branch head:
@@ -208,6 +226,55 @@ if on the closed branch head:
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   parent=6
 
+if not on the closed branch head:
+- updating is no-op
+- "all heads of branch ...." message is displayed
+
+  $ norevtest "all heads of branch default are closed" clean 1
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  all heads of branch "default" are closed
+  parent=1
+
+  $ cd ..
+
+Test updating if "default" branch doesn't exist and no revision is
+checked out (= "default" is used as current branch)
+
+  $ hg init no-default-branch
+  $ cd no-default-branch
+
+  $ hg branch foobar
+  marked working directory as branch foobar
+  (branches are permanent and global, did you want a bookmark?)
+  $ echo a > a
+  $ hg commit -m "#0" -A
+  adding a
+  $ echo 1 >> a
+  $ hg commit -m "#1"
+  $ hg update -q 0
+  $ echo 3 >> a
+  $ hg commit -m "#2"
+  created new head
+  $ hg commit --close-branch -m "#3"
+
+if there is at least one non-closed branch head:
+- update to the tipmost branch head
+
+  $ norevtest "non-closed 1 should be chosen" clean null
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  parent=1
+
+if all branch heads are closed
+- updating is no-op
+- "all branches are closed" message is displayed
+
+  $ hg update -q -C 1
+  $ hg commit --close-branch -m "#4"
+
+  $ norevtest "all branches are closed" clean null
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  all branches are closed
+
   $ cd ../b1
 
 Test obsolescence behavior