core/views: Add SpoilerView class and corresponding show_* function.

Author: rsashank

tests/ui_tools/test_popups.py

@@ -24,6 +24,7 @@
     MsgInfoView,
     PopUpConfirmationView,
     PopUpView,
+    SpoilerView,
     StreamInfoView,
     StreamMembersView,
     UserInfoView,
@@ -917,6 +918,47 @@ def test_keypress_exit_popup(
         assert self.controller.exit_popup.called
 
 
+class TestSpoilerView:
+    @pytest.fixture(autouse=True)
+    def mock_external_classes(self, mocker: MockerFixture) -> None:
+        self.controller = mocker.Mock()
+        mocker.patch.object(
+            self.controller, "maximum_popup_dimensions", return_value=(64, 64)
+        )
+        mocker.patch(MODULE + ".urwid.SimpleFocusListWalker", return_value=[])
+        self.spoiler_view = SpoilerView(self.controller, "Spoiler View", "")
+
+    def test_keypress_any_key(
+        self, widget_size: Callable[[Widget], urwid_Size]
+    ) -> None:
+        key = "a"
+        size = widget_size(self.spoiler_view)
+        self.spoiler_view.keypress(size, key)
+        assert not self.controller.exit_popup.called
+
+    @pytest.mark.parametrize(
+        "key", {*keys_for_command("GO_BACK"), *keys_for_command("ENTER")}
+    )
+    def test_keypress_exit_popup(
+        self, key: str, widget_size: Callable[[Widget], urwid_Size]
+    ) -> None:
+        size = widget_size(self.spoiler_view)
+        self.spoiler_view.keypress(size, key)
+        assert self.controller.exit_popup.called
+
+    def test_keypress_navigation(
+        self,
+        mocker: MockerFixture,
+        widget_size: Callable[[Widget], urwid_Size],
+        navigation_key_expected_key_pair: Tuple[str, str] = ("ENTER", "ENTER"),
+    ) -> None:
+        key, expected_key = navigation_key_expected_key_pair
+        size = widget_size(self.spoiler_view)
+        super_keypress = mocker.patch(MODULE + ".urwid.ListBox.keypress")
+        self.spoiler_view.keypress(size, key)
+        super_keypress.assert_called_once_with(size, expected_key)
+
+
 class TestMsgInfoView:
     @pytest.fixture(autouse=True)
     def mock_external_classes(

zulipterminal/core.py

@@ -42,6 +42,7 @@
     MsgInfoView,
     NoticeView,
     PopUpConfirmationView,
+    SpoilerView,
     StreamInfoView,
     StreamMembersView,
     UserInfoView,
@@ -481,6 +482,11 @@ def report_warning(
         """
         self.view.set_footer_text(text, "task:warning", duration)
 
+    def show_spoiler(self, content: str) -> None:
+        self.show_pop_up(
+            SpoilerView(self, "Spoiler (up/down scrolls)", content), "area:msg"
+        )
+
     def show_media_confirmation_popup(
         self, func: Any, tool: str, media_path: str
     ) -> None:

zulipterminal/ui_tools/views.py

@@ -1076,6 +1076,14 @@ def __init__(
         super().__init__(controller, widgets, "GO_BACK", width, title)
 
 
+class SpoilerView(PopUpView):
+    def __init__(self, controller: Any, title: str, content: str) -> None:
+        width, _ = controller.maximum_popup_dimensions()
+        widget = [urwid.Text(content)]
+
+        super().__init__(controller, widget, "ENTER", width, title)
+
+
 class AboutView(PopUpView):
     def __init__(
         self,