Add -n flag to `ls` to limit the number of todos to be printed.

If given, the -n flag overrides the list_limit configuration flag to
limit the number of todos printed by ls.

In combination with -x, -n does not do anything. Rationale is to keep
the behavior of -x intact, matching the semantics of the original
todo.txt CLI.

test/TestListCommand.py

@@ -226,6 +226,48 @@ class ListCommandTest(CommandTest):
         self.assertFalse(self.todolist.is_dirty())
         self.assertEqual(self.output, '|  1| Foo.\n')
 
+    def test_list31(self):
+        """ Don't show any todos with -n 0 """
+        command = ListCommand(["-n", "0"], self.todolist, self.out, self.error)
+        command.execute()
+
+        self.assertEqual(self.output, "")
+        self.assertEqual(self.errors, "")
+
+    def test_list32(self):
+        """ Only show the top todo. """
+        command = ListCommand(["-n", "1"], self.todolist, self.out, self.error)
+        command.execute()
+
+        self.assertEqual(self.output, "|  1| (C) Foo @Context2 Not@Context +Project1 Not+Project\n")
+        self.assertEqual(self.errors, "")
+
+    def test_list33(self):
+        """ Negative values result in showing all relevent todos. """
+        command = ListCommand(["-n", "-1"], self.todolist, self.out, self.error)
+        command.execute()
+
+        self.assertEqual(self.output, "|  1| (C) Foo @Context2 Not@Context +Project1 Not+Project\n|  4| (C) Drink beer @ home\n|  5| (C) 13 + 29 = 42\n|  2| (D) Bar @Context1 +Project2\n")
+        self.assertEqual(self.errors, "")
+
+    def test_list34(self):
+        """ Test non-integer value for -n """
+        config(p_overrides={('ls', 'list_limit'): '2'})
+
+        command = ListCommand(["-n", "foo"], self.todolist, self.out, self.error)
+        command.execute()
+
+        self.assertEqual(self.output, "|  1| (C) Foo @Context2 Not@Context +Project1 Not+Project\n|  4| (C) Drink beer @ home\n")
+        self.assertEqual(self.errors, "")
+
+    def test_list35(self):
+        """ -x flag takes precedence over -n """
+        command = ListCommand(["-x", "-n", "foo"], self.todolist, self.out, self.error)
+        command.execute()
+
+        self.assertEqual(self.output, "|  1| (C) Foo @Context2 Not@Context +Project1 Not+Project\n|  3| (C) Baz @Context1 +Project1 key:value\n|  4| (C) Drink beer @ home\n|  5| (C) 13 + 29 = 42\n|  2| (D) Bar @Context1 +Project2\n|  6| x 2014-12-12 Completed but with date:2014-12-12\n")
+        self.assertEqual(self.errors, "")
+
     def test_help(self):
         command = ListCommand(["help"], self.todolist, self.out, self.error)
         command.execute()

topydo/commands/ListCommand.py

@@ -49,7 +49,7 @@ class ListCommand(ExpressionCommand):
         return True
 
     def _process_flags(self):
-        opts, args = self.getopt('f:s:x')
+        opts, args = self.getopt('f:n:s:x')
 
         for opt, value in opts:
             if opt == '-x':
@@ -64,6 +64,11 @@ class ListCommand(ExpressionCommand):
                         self.printer = IcalPrinter(self.todolist)
                 else:
                     self.printer = None
+            elif opt == '-n':
+                try:
+                    self.limit = int(value)
+                except ValueError:
+                    pass # use default value in configuration
 
         self.args = args
 

topydo/lib/ExpressionCommand.py

@@ -37,6 +37,7 @@ class ExpressionCommand(Command):
 
         self.sort_expression = config().sort_string()
         self.show_all = False
+        self.limit = config().list_limit()
         # Commands using last argument differently (i.e as something other than
         # todo ID/expression) have to set attribute below to True.
         self.last_argument = False
@@ -75,7 +76,7 @@ class ExpressionCommand(Command):
         filters += arg_filters()
 
         if not self.show_all:
-            filters.append(Filter.LimitFilter(config().list_limit()))
+            filters.append(Filter.LimitFilter(self.limit))
 
         return filters