Make 0 a usable count for :tab-focus

Fixes #1768

qutebrowser/browser/commands.py

@@ -956,7 +956,7 @@ class CommandDispatcher:
 
     @cmdutils.register(instance='command-dispatcher', scope='window')
     @cmdutils.argument('index', choices=['last'])
-    @cmdutils.argument('count', count=True)
+    @cmdutils.argument('count', count=True, zero_count=True)
     def tab_focus(self, index: typing.Union[str, int]=None, count=None):
         """Select the tab given as argument/[count].
 
@@ -969,6 +969,7 @@ class CommandDispatcher:
                    Negative indices count from the end, such that -1 is the
                    last tab.
             count: The tab index to focus, starting with 1.
+                   The special value 0 focuses the rightmost tab.
         """
         if index == 'last':
             self._tab_focus_last()
@@ -977,7 +978,10 @@ class CommandDispatcher:
         if index is None:
             self.tab_next()
             return
-        if index < 0:
+        elif index == 0:
+            index = self._count()
+
+        elif index < 0:
             index = self._count() + index + 1
 
         if 1 <= index <= self._count():

qutebrowser/commands/command.py

@@ -33,12 +33,15 @@ class ArgInfo:
 
     """Information about an argument."""
 
-    def __init__(self, win_id=False, count=False, flag=None, hide=False,
+    def __init__(self, win_id=False, count=False, hide=False, metavar=None,
-                 metavar=None, completion=None, choices=None):
+                 zero_count=False, flag=None, completion=None, choices=None):
         if win_id and count:
             raise TypeError("Argument marked as both count/win_id!")
+        if zero_count and not count:
+            raise TypeError("zero_count argument cannot exist without count!")
         self.win_id = win_id
         self.count = count
+        self.zero_count = zero_count
         self.flag = flag
         self.hide = hide
         self.metavar = metavar
@@ -48,6 +51,7 @@ class ArgInfo:
     def __eq__(self, other):
         return (self.win_id == other.win_id and
                 self.count == other.count and
+                self.zero_count == other.zero_count and
                 self.flag == other.flag and
                 self.hide == other.hide and
                 self.metavar == other.metavar and
@@ -57,6 +61,7 @@ class ArgInfo:
     def __repr__(self):
         return utils.get_repr(self, win_id=self.win_id, count=self.count,
                               flag=self.flag, hide=self.hide,
+                              zero_count=self.zero_count,
                               metavar=self.metavar, completion=self.completion,
                               choices=self.choices, constructor=True)
 
@@ -137,6 +142,7 @@ class Command:
         self.opt_args = collections.OrderedDict()
         self.namespace = None
         self._count = None
+        self._zero_count = None
         self.pos_args = []
         self.desc = None
         self.flags_with_args = []
@@ -148,7 +154,7 @@ class Command:
 
         self._inspect_func()
 
-    def _check_prerequisites(self, win_id):
+    def _check_prerequisites(self, win_id, count):
         """Check if the command is permitted to run currently.
 
         Args:
@@ -164,6 +170,11 @@ class Command:
                 "{}: Only available with {} "
                 "backend.".format(self.name, self.backend.name))
 
+        if count == 0 and not self._zero_count:
+            raise cmdexc.PrerequisitesError(
+                "{}: A zero count is not allowed for this command!"
+                .format(self.name))
+
         if self.deprecated:
             message.warning('{} is deprecated - {}'.format(self.name,
                                                            self.deprecated))
@@ -235,6 +246,9 @@ class Command:
                 assert param.kind != inspect.Parameter.POSITIONAL_ONLY
                 if param.name == 'self':
                     continue
+                arg_info = self.get_arg_info(param)
+                if arg_info.count:
+                    self._zero_count = arg_info.zero_count
                 if self._inspect_special_param(param):
                     continue
                 if (param.kind == inspect.Parameter.KEYWORD_ONLY and
@@ -511,7 +525,7 @@ class Command:
                 e.status, e))
             return
         self._count = count
-        self._check_prerequisites(win_id)
+        self._check_prerequisites(win_id, count)
         posargs, kwargs = self._get_call_args(win_id)
         log.commands.debug('Calling {}'.format(
             debug_utils.format_call(self.handler, posargs, kwargs)))

qutebrowser/keyinput/basekeyparser.py

@@ -146,9 +146,6 @@ class BaseKeyParser(QObject):
             (countstr, cmd_input) = re.match(r'^(\d*)(.*)',
                                              self._keystring).groups()
             count = int(countstr) if countstr else None
-            if count == 0 and not cmd_input:
-                cmd_input = self._keystring
-                count = None
         else:
             cmd_input = self._keystring
             count = None

tests/end2end/features/tabs.feature

@@ -255,6 +255,17 @@ Feature: Tab management
             - data/numbers/2.txt (active)
             - data/numbers/3.txt
 
+    Scenario: :tab-focus with count 0
+        When I open data/numbers/1.txt
+        And I open data/numbers/2.txt in a new tab
+        And I open data/numbers/3.txt in a new tab
+        And I run :tab-focus with count 1
+        And I run :tab-focus with count 0
+        Then the following tabs should be open:
+            - data/numbers/1.txt
+            - data/numbers/2.txt
+            - data/numbers/3.txt (active)
+
     Scenario: :tab-focus with invalid negative index
         When I open data/numbers/1.txt
         And I open data/numbers/2.txt in a new tab

tests/unit/commands/test_cmdutils.py

@@ -423,6 +423,17 @@ class TestArgument:
 
         assert str(excinfo.value) == "Argument marked as both count/win_id!"
 
+    def test_count_and_zero_count_arg(self):
+        with pytest.raises(TypeError) as excinfo:
+            @cmdutils.argument('arg', count=False, zero_count=True)
+            def fun(arg=0):
+                """Blah."""
+                pass
+
+        expected = "zero_count argument cannot exist without count!"
+
+        assert str(excinfo.value) == expected
+
     def test_no_docstring(self, caplog):
         with caplog.at_level(logging.WARNING):
             @cmdutils.register()

tests/unit/keyinput/test_basekeyparser.py

@@ -246,9 +246,10 @@ class TestKeyChain:
         assert keyparser._keystring == ''
 
     def test_0_press(self, handle_text, keyparser):
-        handle_text((Qt.Key_0, '0'))
+        handle_text((Qt.Key_X, '0'),
+                    (Qt.Key_B, 'b'), (Qt.Key_A, 'a'))
         keyparser.execute.assert_called_once_with(
-            '0', keyparser.Type.chain, None)
+            'ba', keyparser.Type.chain, 0)
         assert keyparser._keystring == ''
 
     def test_ambiguous_keychain(self, qapp, handle_text, config_stub,
@@ -314,9 +315,8 @@ class TestCount:
 
     def test_count_0(self, handle_text, keyparser):
         handle_text((Qt.Key_0, '0'), (Qt.Key_B, 'b'), (Qt.Key_A, 'a'))
-        calls = [mock.call('0', keyparser.Type.chain, None),
+        keyparser.execute.assert_called_once_with(
-                 mock.call('ba', keyparser.Type.chain, None)]
+            'ba', keyparser.Type.chain, 0)
-        keyparser.execute.assert_has_calls(calls)
         assert keyparser._keystring == ''
 
     def test_count_42(self, handle_text, keyparser):