diff -r c936a243346a -r b4dfafda72c2 hgext/evolve.py
--- a/hgext/evolve.py	Wed Sep 09 22:25:37 2015 -0400
+++ b/hgext/evolve.py	Thu Sep 10 16:24:50 2015 -0400
@@ -1988,12 +1988,14 @@
 @command('^previous',
          [('B', 'move-bookmark', False,
              _('move active bookmark after update')),
-          ('', 'merge', False, _('bring uncommitted change along'))],
-         '[-B]')
+          ('', 'merge', False, _('bring uncommitted change along')),
+          ('n', 'dry-run', False, _('do not perform actions, just print what would be done'))],
+         '[OPTION]...')
 def cmdprevious(ui, repo, **opts):
     """update to parent and display summary lines"""
     wkctx = repo[None]
     wparents = wkctx.parents()
+    dryrunopt = opts['dry_run']
     if len(wparents) != 1:
         raise util.Abort('merge in progress')
     if not opts['merge']:
@@ -2009,13 +2011,18 @@
         p = parents[0]
         bm = bmactive(repo)
         shouldmove = opts.get('move_bookmark') and bm is not None
-        ret = hg.update(repo, p.rev())
-        if not ret:
+        if dryrunopt:
+            ui.write('hg update %s;\n' % p.rev())
             if shouldmove:
-                repo._bookmarks[bm] = p.node()
-                repo._bookmarks.write()
-            else:
-                bmdeactivate(repo)
+                ui.write('hg bookmark %s -r %s;\n' % (bm, p.rev()))
+        else:
+            ret = hg.update(repo, p.rev())
+            if not ret:
+                if shouldmove:
+                    repo._bookmarks[bm] = p.node()
+                    repo._bookmarks.write()
+                else:
+                    bmdeactivate(repo)
         displayer.show(p)
         return 0
     else:
@@ -2028,8 +2035,9 @@
          [('B', 'move-bookmark', False,
              _('move active bookmark after update')),
           ('', 'merge', False, _('bring uncommitted change along')),
-          ('', 'evolve', False, _('evolve the next changeset if necessary'))],
-         '[-B]')
+          ('', 'evolve', False, _('evolve the next changeset if necessary')),
+          ('n', 'dry-run', False, _('do not perform actions, just print what would be done'))],
+         '[OPTION]...')
 def cmdnext(ui, repo, **opts):
     """update to next child
 
@@ -2038,6 +2046,7 @@
     The summary line of the destination is displayed for clarity"""
     wkctx = repo[None]
     wparents = wkctx.parents()
+    dryrunopt = opts['dry_run']
     if len(wparents) != 1:
         raise util.Abort('merge in progress')
     if not opts['merge']:
@@ -2053,13 +2062,18 @@
         c = children[0]
         bm = bmactive(repo)
         shouldmove = opts.get('move_bookmark') and bm is not None
-        ret = hg.update(repo, c.rev())
-        if not ret:
+        if dryrunopt:
+            ui.write('hg update %s;\n' % c.rev())
             if shouldmove:
-                repo._bookmarks[bm] = c.node()
-                repo._bookmarks.write()
-            else:
-                bmdeactivate(repo)
+                ui.write('hg bookmark %s -r %s;\n' % (bm, c.rev()))
+        else:
+            ret = hg.update(repo, c.rev())
+            if not ret:
+                if shouldmove:
+                    repo._bookmarks[bm] = c.node()
+                    repo._bookmarks.write()
+                else:
+                    bmdeactivate(repo)
         displayer.show(c)
         result = 0
     elif children:
@@ -2085,7 +2099,7 @@
             return 1
         else:
             cmdutil.bailifchanged(repo)
-            result = _solveone(ui, repo, repo[aspchildren[0]], False,
+            result = _solveone(ui, repo, repo[aspchildren[0]], dryrunopt,
                                False, lambda:None, category='unstable')
             if not result:
                 ui.status(_('working directory now at %s\n') % repo['.'])