diff --git a/crates/matrix-sdk-ui/src/timeline/event_item/mod.rs b/crates/matrix-sdk-ui/src/timeline/event_item/mod.rs
index 475f5e23f..aa0ecbc54 100644
--- a/crates/matrix-sdk-ui/src/timeline/event_item/mod.rs
+++ b/crates/matrix-sdk-ui/src/timeline/event_item/mod.rs
@@ -716,23 +716,24 @@ impl ReactionsByKeyBySender {
 mod tests {
     use assert_matches::assert_matches;
     use assert_matches2::assert_let;
-    use matrix_sdk::test_utils::logged_in_client;
+    use matrix_sdk::test_utils::{events::EventFactory, logged_in_client};
     use matrix_sdk_base::{
         deserialized_responses::SyncTimelineEvent, latest_event::LatestEvent, sliding_sync::http,
         MinimalStateEvent, OriginalMinimalStateEvent,
     };
     use matrix_sdk_test::{async_test, sync_timeline_event};
     use ruma::{
+        event_id,
         events::{
             room::{
                 member::RoomMemberEventContent,
                 message::{MessageFormat, MessageType},
             },
-            AnySyncTimelineEvent,
+            AnySyncTimelineEvent, BundledMessageLikeRelations,
         },
         room_id,
         serde::Raw,
-        user_id, RoomId, UInt, UserId,
+        uint, user_id, MilliSecondsSinceUnixEpoch, RoomId, UInt, UserId,
     };
 
     use super::{EventTimelineItem, Profile};
@@ -773,48 +774,30 @@ mod tests {
         // contains a bundled edit,
         let room_id = room_id!("!q:x.uk");
         let user_id = user_id!("@t:o.uk");
-        let event = sync_timeline_event!({
-            "event_id": "$eventid6",
-            "sender": user_id,
-            "origin_server_ts": 42,
-            "type": "m.room.message",
-            "room_id": room_id,
-            "content": {
-                "body":  "**My M**",
-                "format": "org.matrix.custom.html",
-                "formatted_body": "<b>My M</b>" ,
-                "msgtype": "m.text"
-            },
-            "unsigned": {
-                "m.relations": {
-                  "m.replace" : {
-                    "sender" : user_id,
-                    "content" : {
-                      "format" : "org.matrix.custom.html",
-                      "formatted_body" : " * <b>Updated!</b>",
-                      "m.relates_to" : {
-                        "event_id" : "$eventid6",
-                        "rel_type" : "m.replace"
-                      },
-                      "m.new_content": {
-                        "body" : "Updated!",
-                        "formatted_body" : "<b>Updated!</b>",
-                        "msgtype" : "m.text",
-                        "format" : "org.matrix.custom.html"
-                      },
-                      "msgtype" : "m.text",
-                      "body" : " * Updated!"
-                    },
-                    "origin_server_ts" : 43,
-                    "room_id" : room_id,
-                    "event_id" : "$edit-event-id",
-                    "user_id" : user_id,
-                    "type" : "m.room.message",
-                  }
-                }
-            }
-        })
-        .into();
+
+        let f = EventFactory::new();
+
+        let original_event_id = event_id!("$original");
+
+        let mut relations = BundledMessageLikeRelations::new();
+        relations.replace = Some(Box::new(
+            f.text_html(" * Updated!", " * <b>Updated!</b>")
+                .edit(
+                    original_event_id,
+                    MessageType::text_html("Updated!", "<b>Updated!</b>").into(),
+                )
+                .event_id(event_id!("$edit"))
+                .sender(user_id)
+                .into_raw_sync(),
+        ));
+
+        let event = f
+            .text_html("**My M**", "<b>My M</b>")
+            .sender(user_id)
+            .event_id(original_event_id)
+            .bundled_relations(relations)
+            .server_ts(MilliSecondsSinceUnixEpoch(uint!(42)))
+            .into_sync();
 
         let client = logged_in_client(None).await;
 
diff --git a/crates/matrix-sdk-ui/src/timeline/tests/edit.rs b/crates/matrix-sdk-ui/src/timeline/tests/edit.rs
index 33fa44f02..ddfcdead8 100644
--- a/crates/matrix-sdk-ui/src/timeline/tests/edit.rs
+++ b/crates/matrix-sdk-ui/src/timeline/tests/edit.rs
@@ -19,11 +19,13 @@ use eyeball_im::VectorDiff;
 use matrix_sdk::deserialized_responses::{
     AlgorithmInfo, EncryptionInfo, VerificationLevel, VerificationState,
 };
-use matrix_sdk_test::{async_test, sync_timeline_event, ALICE};
+use matrix_sdk_test::{async_test, ALICE};
 use ruma::{
     event_id,
-    events::room::message::{MessageType, RedactedRoomMessageEventContent},
-    server_name, EventId,
+    events::{
+        room::message::{MessageType, RedactedRoomMessageEventContent},
+        BundledMessageLikeRelations,
+    },
 };
 use stream_assert::{assert_next_matches, assert_pending};
 
@@ -108,45 +110,36 @@ async fn test_aggregated_sanitized() {
     let timeline = TestTimeline::new();
     let mut stream = timeline.subscribe().await;
 
-    let original_event_id = EventId::new(server_name!("dummy.server"));
-    let ev = sync_timeline_event!({
-        "content": {
-            "formatted_body": "<strong>original</strong> message",
-            "format": "org.matrix.custom.html",
-            "body": "**original** message",
-            "msgtype": "m.text"
-        },
-        "event_id": &original_event_id,
-        "origin_server_ts": timeline.event_builder.next_server_ts(),
-        "sender": *ALICE,
-        "type": "m.room.message",
-        "unsigned": {
-            "m.relations": {
-                "m.replace": {
-                    "content": {
-                        "formatted_body": "* <edited/> <strong>better</strong> message",
-                        "format": "org.matrix.custom.html",
-                        "body": "* !!edited!! **better** message",
-                        "m.new_content": {
-                            "formatted_body": "<edited/> <strong>better</strong> message",
-                            "format": "org.matrix.custom.html",
-                            "body": "!!edited!! **better** message",
-                            "msgtype": "m.text"
-                        },
-                        "m.relates_to": {
-                            "event_id": original_event_id,
-                            "rel_type": "m.replace"
-                        },
-                        "msgtype": "m.text"
-                    },
-                    "event_id": EventId::new(server_name!("dummy.server")),
-                    "origin_server_ts": timeline.event_builder.next_server_ts(),
-                    "sender": *ALICE,
-                    "type": "m.room.message",
-                }
-            }
-        }
-    });
+    let original_event_id = event_id!("$original");
+    let edit_event_id = event_id!("$edit");
+
+    let f = &timeline.factory;
+
+    let mut relations = BundledMessageLikeRelations::new();
+    relations.replace = Some(Box::new(
+        f.text_html(
+            "* !!edited!! **better** message",
+            "* <edited/> <strong>better</strong> message",
+        )
+        .edit(
+            original_event_id,
+            MessageType::text_html(
+                "!!edited!! **better** message",
+                "<edited/> <strong>better</strong> message",
+            )
+            .into(),
+        )
+        .event_id(edit_event_id)
+        .sender(*ALICE)
+        .into_raw_sync(),
+    ));
+
+    let ev = f
+        .text_html("**original** message", "<strong>original</strong> message")
+        .sender(*ALICE)
+        .event_id(original_event_id)
+        .bundled_relations(relations);
+
     timeline.handle_live_event(ev).await;
 
     let item = assert_next_matches!(stream, VectorDiff::PushBack { value } => value);
@@ -246,38 +239,21 @@ async fn test_relations_edit_overrides_pending_edit() {
     assert_pending!(stream);
 
     // Now we receive the original event, with a bundled relations group.
-    let ev = sync_timeline_event!({
-        "content": {
-            "body": "original",
-            "msgtype": "m.text"
-        },
-        "event_id": &original_event_id,
-        "origin_server_ts": timeline.event_builder.next_server_ts(),
-        "sender": *ALICE,
-        "type": "m.room.message",
-        "unsigned": {
-            "m.relations": {
-                "m.replace": {
-                    "content": {
-                        "body": "* edit 2",
-                        "m.new_content": {
-                            "body": "edit 2",
-                            "msgtype": "m.text"
-                        },
-                        "m.relates_to": {
-                            "event_id": original_event_id,
-                            "rel_type": "m.replace"
-                        },
-                        "msgtype": "m.text"
-                    },
-                    "event_id": edit2_event_id,
-                    "origin_server_ts": timeline.event_builder.next_server_ts(),
-                    "sender": *ALICE,
-                    "type": "m.room.message",
-                }
-            }
-        }
-    });
+    let mut relations = BundledMessageLikeRelations::new();
+    relations.replace = Some(Box::new(
+        f.text_msg("* edit 2")
+            .edit(original_event_id, MessageType::text_plain("edit 2").into())
+            .event_id(edit2_event_id)
+            .sender(*ALICE)
+            .into_raw_sync(),
+    ));
+
+    let ev = f
+        .text_msg("original")
+        .sender(*ALICE)
+        .event_id(original_event_id)
+        .bundled_relations(relations);
+
     timeline.handle_live_event(ev).await;
 
     let item = assert_next_matches!(stream, VectorDiff::PushBack { value } => value);
diff --git a/crates/matrix-sdk/src/test_utils/events.rs b/crates/matrix-sdk/src/test_utils/events.rs
index ce7b0bb5f..260e210b4 100644
--- a/crates/matrix-sdk/src/test_utils/events.rs
+++ b/crates/matrix-sdk/src/test_utils/events.rs
@@ -34,7 +34,7 @@ use ruma::{
             message::{Relation, RoomMessageEventContent, RoomMessageEventContentWithoutRelation},
             redaction::RoomRedactionEventContent,
         },
-        AnySyncTimelineEvent, AnyTimelineEvent, EventContent,
+        AnySyncTimelineEvent, AnyTimelineEvent, BundledMessageLikeRelations, EventContent,
     },
     serde::Raw,
     server_name, EventId, MilliSecondsSinceUnixEpoch, OwnedEventId, OwnedRoomId,
@@ -43,18 +43,19 @@ use ruma::{
 use serde::Serialize;
 use serde_json::json;
 
-#[derive(Debug, Default, Serialize)]
+#[derive(Debug, Default)]
 struct Unsigned {
     transaction_id: Option<OwnedTransactionId>,
+    relations: Option<BundledMessageLikeRelations<Raw<AnySyncTimelineEvent>>>,
 }
 
 #[derive(Debug)]
-pub struct EventBuilder<E: EventContent> {
+pub struct EventBuilder<C: EventContent> {
     sender: Option<OwnedUserId>,
     room: Option<OwnedRoomId>,
     event_id: Option<OwnedEventId>,
     redacts: Option<OwnedEventId>,
-    content: E,
+    content: C,
     server_ts: MilliSecondsSinceUnixEpoch,
     unsigned: Option<Unsigned>,
     state_key: Option<String>,
@@ -90,6 +91,21 @@ where
         self
     }
 
+    /// Adds bundled relations to this event.
+    ///
+    /// Ideally, we'd type-check that an event passed as a relation is the same
+    /// type as this one, but it's not trivial to do so because this builder
+    /// is only generic on the event's *content*, not the event type itself;
+    /// doing so would require many changes, and this is testing code after
+    /// all.
+    pub fn bundled_relations(
+        mut self,
+        relations: BundledMessageLikeRelations<Raw<AnySyncTimelineEvent>>,
+    ) -> Self {
+        self.unsigned.get_or_insert_with(Default::default).relations = Some(relations);
+        self
+    }
+
     pub fn state_key(mut self, state_key: impl Into<String>) -> Self {
         self.state_key = Some(state_key.into());
         self
@@ -122,9 +138,23 @@ where
         if let Some(redacts) = self.redacts {
             map.insert("redacts".to_owned(), json!(redacts));
         }
+
         if let Some(unsigned) = self.unsigned {
-            map.insert("unsigned".to_owned(), json!(unsigned));
+            let mut unsigned_json = json!({});
+
+            // We can't plain serialize `Unsigned`, otherwise this would result in some
+            // `null` fields when options are set to none, which Ruma rejects.
+            let unsigned_obj = unsigned_json.as_object_mut().unwrap();
+            if let Some(transaction_id) = unsigned.transaction_id {
+                unsigned_obj.insert("transaction_id".to_owned(), json!(transaction_id));
+            }
+            if let Some(relations) = unsigned.relations {
+                unsigned_obj.insert("m.relations".to_owned(), json!(relations));
+            }
+
+            map.insert("unsigned".to_owned(), unsigned_json);
         }
+
         if let Some(state_key) = self.state_key {
             map.insert("state_key".to_owned(), json!(state_key));
         }