Add :tab-give and :tab-take commands and tests

doc/help/commands.asciidoc

@@ -85,11 +85,13 @@ It is possible to run or bind multiple commands by separating them with `;;`.
 |<<tab-close,tab-close>>|Close the current/[count]th tab.
 |<<tab-detach,tab-detach>>|Detach the current tab to its own window.
 |<<tab-focus,tab-focus>>|Select the tab given as argument/[count].
+|<<tab-give,tab-give>>|Give the current tab to another window.
 |<<tab-move,tab-move>>|Move the current tab according to the argument and [count].
 |<<tab-next,tab-next>>|Switch to the next tab, or switch [count] tabs forward.
 |<<tab-only,tab-only>>|Close all tabs except for the current one.
 |<<tab-pin,tab-pin>>|Pin/Unpin the current/[count]th tab.
 |<<tab-prev,tab-prev>>|Switch to the previous tab, or switch [count] tabs back.
+|<<tab-take,tab-take>>|Take a tab from another window.
 |<<unbind,unbind>>|Unbind a keychain.
 |<<undo,undo>>|Re-open a closed tab.
 |<<version,version>>|Show version information.
@@ -967,6 +969,15 @@ If neither count nor index are given, it behaves like tab-next. If both are give
 ==== count
 The tab index to focus, starting with 1.
 
+[[tab-give]]
+=== tab-give
+Syntax: +:tab-give 'win-id'+
+
+Give the current tab to another window.
+
+==== positional arguments
+* +'win-id'+: The window ID of the window to give the current tab to.
+
 [[tab-move]]
 === tab-move
 Syntax: +:tab-move ['index']+
@@ -1019,6 +1030,16 @@ Switch to the previous tab, or switch [count] tabs back.
 ==== count
 How many tabs to switch back.
 
+[[tab-take]]
+=== tab-take
+Syntax: +:tab-take 'index'+
+
+Take a tab from another window.
+
+==== positional arguments
+* +'index'+: The [win_id/]index of the tab to take. Or a substring in which case the closest match will be taken.
+
+
 [[unbind]]
 === unbind
 Syntax: +:unbind [*--mode* 'mode'] 'key'+

qutebrowser/browser/commands.py

@@ -523,6 +523,39 @@ class CommandDispatcher:
         cur_widget = self._current_widget()
         self._tabbed_browser.close_tab(cur_widget, add_undo=False)
 
+    @cmdutils.register(instance='command-dispatcher', scope='window')
+    @cmdutils.argument('index', completion=miscmodels.buffer)
+    def tab_take(self, index):
+        """Take a tab from another window.
+
+        Args:
+            index: The [win_id/]index of the tab to take. Or a substring
+                   in which case the closest match will be taken.
+        """
+        tabbed_browser, tab = self._resolve_buffer_index(index)
+
+        if tabbed_browser is self._tabbed_browser:
+            raise cmdexc.CommandError("Can't take a tab from the same window")
+
+        self._open(tab.url(), tab=True)
+        tabbed_browser.close_tab(tab, add_undo=False)
+
+    @cmdutils.register(instance='command-dispatcher', scope='window')
+    @cmdutils.argument('win_id', completion=miscmodels.window)
+    def tab_give(self, win_id: int):
+        """Give the current tab to another window.
+
+        Args:
+            win_id: The window ID of the window to give the current tab to.
+        """
+        if win_id == self._win_id:
+            raise cmdexc.CommandError("Can't give a tab to the same window")
+
+        tabbed_browser = objreg.get('tabbed-browser', scope='window',
+                                    window=win_id)
+        tabbed_browser.tabopen(self._current_url())
+        self._tabbed_browser.close_tab(self._current_widget(), add_undo=False)
+
     def _back_forward(self, tab, bg, window, count, forward):
         """Helper function for :back/:forward."""
         history = self._current_widget().history

qutebrowser/completion/models/miscmodels.py

@@ -122,3 +122,22 @@ def buffer(*, info=None):  # pylint: disable=unused-argument
         model.add_category(cat)
 
     return model
+
+
+def window(*, info=None):  # pylint: disable=unused-argument
+    """A model to complete on all open windows."""
+    model = completionmodel.CompletionModel(column_widths=(6, 30, 64))
+
+    windows = []
+
+    for win_id in objreg.window_registry:
+        tabbed_browser = objreg.get('tabbed-browser', scope='window',
+                                    window=win_id)
+        tab_titles = (tab.title() for tab in tabbed_browser.widgets())
+        windows.append(("{}".format(win_id),
+                        objreg.window_registry[win_id].windowTitle(),
+                        ", ".join(tab_titles)))
+
+    model.add_category(listcategory.ListCategory("Windows", windows))
+
+    return model

tests/end2end/features/tabs.feature

@@ -1010,6 +1010,56 @@ Feature: Tab management
         And I run :buffer "1/2/3"
         Then the error "No matching tab for: 1/2/3" should be shown
 
+    # :tab-take
+
+    @xfail_norun
+    Scenario: Take a tab from another window
+        Given I have a fresh instance
+        When I open data/numbers/1.txt
+        And I open data/numbers/2.txt in a new window
+        And I run :tab-take 0/1
+        Then the session should look like:
+            windows:
+            - tabs:
+              - history:
+                - url: about:blank
+            - tabs:
+              - history:
+                - url: http://localhost:*/data/numbers/2.txt
+              - history:
+                - url: http://localhost:*/data/numbers/1.txt
+
+    Scenario: Take a tab from the same window
+        Given I have a fresh instance
+        When I open data/numbers/1.txt
+        And I run :tab-take 0/1
+        Then the error "Can't take a tab from the same window" should be shown
+
+    # :tab-give
+
+    @xfail_norun
+    Scenario: Give a tab to another window
+        Given I have a fresh instance
+        When I open data/numbers/1.txt
+        And I open data/numbers/2.txt in a new window
+        And I run :tab-give 0
+        Then the session should look like:
+            windows:
+            - tabs:
+              - history:
+                - url: http://localhost:*/data/numbers/1.txt
+              - history:
+                - url: http://localhost:*/data/numbers/2.txt
+            - tabs:
+              - history:
+                - url: about:blank
+
+    Scenario: Give a tab to the same window
+        Given I have a fresh instance
+        When I open data/numbers/1.txt
+        And I run :tab-give 0
+        Then the error "Can't give a tab to the same window" should be shown
+
     # Other
 
     Scenario: Using :tab-next after closing last tab (#1448)