Hide spoilers from desktop notifications (#31699)

* Hide spoilers from desktop notifications

* Replace unicode blocks with spoiler tag

* Run prettier

* Add comments

apps/web/test/unit-tests/Notifier-test.ts

@@ -358,6 +358,46 @@ describe("Notifier", () => {
                 reply,
             );
         });
+
+        it.each([
+            ["This was a triumph", "This was a triumph", "This was a triumph"],
+            ["This was a triumph", "<span data-mx-spoiler>This was a triumph</span>", "[Spoiler]"],
+            ["This was a triumph", '<span data-mx-spoiler="triumph">This was a triumph</span>', "[Spoiler]"],
+            ["foo bar baz", "foo <span data-mx-spoiler>bar</span> baz", "foo [Spoiler] baz"],
+            ["foo foo foo", "foo <span data-mx-spoiler>foo</span> foo", "foo [Spoiler] foo"],
+            [
+                "a b c d e",
+                "a <span data-mx-spoiler>b</span> c <span data-mx-spoiler>d</span> e",
+                "a [Spoiler] c [Spoiler] e",
+            ],
+            ["foo  foo", "foo <span data-mx-spoiler></span> foo", "foo [Spoiler] foo"],
+            ["foo bar baz", "foo <span data-mx-spoiler>b<em>a</em>r</span> baz", "foo [Spoiler] baz"],
+            ["foobar", "<span data-mx-spoiler>foo</span><span data-mx-spoiler>bar</span>", "[Spoiler][Spoiler]"],
+            ["foo bar baz", "<strong>foo <span data-mx-spoiler>bar</span> baz</strong>", "foo [Spoiler] baz"],
+            ["foo <bar> baz", "foo <span data-mx-spoiler>&lt;bar&gt;</span> baz", "foo [Spoiler] baz"],
+            ["foo\nbar\nbaz", "foo<span data-mx-spoiler><br>bar<br></span>baz", "foo[Spoiler]baz"],
+        ])("should hide spoilers in notification", (body, formattedBody, expected) => {
+            const spoilerEvent = mkEvent({
+                event: true,
+                type: EventType.RoomMessage,
+                user: mockClient.getSafeUserId(),
+                room: testRoom.roomId,
+                content: {
+                    msgtype: MsgType.Text,
+                    body: body,
+                    format: "org.matrix.custom.html",
+                    formatted_body: formattedBody,
+                },
+            });
+            Notifier.displayPopupNotification(spoilerEvent, testRoom);
+            expect(MockPlatform.displayNotification).toHaveBeenCalledWith(
+                "@bob:example.org (!room1:server)",
+                expected,
+                expect.any(String),
+                testRoom,
+                spoilerEvent,
+            );
+        });
     });
 
     describe("getSoundForRoom", () => {