[FIX] collaborative: check all overlapping zones

Steps to reproduce:
- merge A2:A3 and F1:F2

Then, concurrently:
- Alice merges A1:A3 (increase the current merge) and C1:C2
- Bob removes merges in A2:A3 and F1:F2

Assuming Alice's revision arrives first to the server (`executed` in the code).
When Bob's revision is transformed against Alice's, both zones in Bob's
command are kept, which makes the command invalid since A2:A3 is no longer
a merge (it is now A1:A3). Because it's invalid, the entire command is
rejected, even though F1:F2 should still be un-merged to preserve Bob's
intention.

The merge transformation is wrong.
The current code keeps a zone if at least one of the zones in the executed
command doesn't overlap.

But it should check all zones and should be kept if none are overlapping.
Said differently: the zone should be dropped if it overlaps any of the
`executed.target` zone.

Task: 4736986
Part-of: #6138
Signed-off-by: Pierre Rousseau (pro) <pro@odoo.com>
Signed-off-by: Lucas Lefèvre (lul) <lul@odoo.com>

Author: LucasLefevre

src/collaborative/ot/ot_specific.ts

@@ -140,10 +140,8 @@ function mergeTransformation(
   }
   const target: Zone[] = [];
   for (const zone1 of toTransform.target) {
-    for (const zone2 of executed.target) {
-      if (!overlap(zone1, zone2)) {
-        target.push({ ...zone1 });
-      }
+    if (executed.target.every((zone2) => !overlap(zone1, zone2))) {
+      target.push(zone1);
     }
   }
   if (target.length) {

tests/collaborative/collaborative.test.ts

@@ -1,7 +1,7 @@
 import { Model, UIPlugin } from "../../src";
 import { DEFAULT_REVISION_ID, MESSAGE_VERSION } from "../../src/constants";
 import { functionRegistry } from "../../src/functions";
-import { getDefaultCellHeight, range, toCartesian, toZone } from "../../src/helpers";
+import { getDefaultCellHeight, range, toCartesian, toZone, zoneToXc } from "../../src/helpers";
 import { featurePluginRegistry } from "../../src/plugins";
 import { Command, CommandResult, CoreCommand, DataValidationCriterion } from "../../src/types";
 import { CollaborationMessage } from "../../src/types/collaborative/transport_service";
@@ -30,6 +30,7 @@ import {
   selectCell,
   setCellContent,
   setStyle,
+  unMerge,
   undo,
   ungroupHeaders,
 } from "../test_helpers/commands_helpers";
@@ -380,6 +381,20 @@ describe("Multi users synchronisation", () => {
     );
   });
 
+  test("concurrent overlapping and non overlapping merge operations", () => {
+    const sheetId = alice.getters.getActiveSheetId();
+    merge(alice, "A2:A3");
+    merge(alice, "F1:F2");
+    network.concurrent(() => {
+      merge(alice, "A1:A3, C1:C2");
+      unMerge(bob, "A2:A3, F1:F2");
+    });
+    expect([alice, bob, charlie]).toHaveSynchronizedValue(
+      (user) => user.getters.getMerges(sheetId).map(zoneToXc),
+      ["A1:A3", "C1:C2"]
+    );
+  });
+
   test("Command not allowed is not dispatched to others users", () => {
     const spy = jest.spyOn(network, "sendMessage");
     setCellContent(alice, "A1", "hello", "invalidSheetId");

tests/collaborative/ot/ot_merged.test.ts

@@ -61,6 +61,11 @@ describe("OT with ADD_MERGE", () => {
         const result = transform(command, addMerge);
         expect(result).toBeUndefined();
       });
+      test("some overlapping merges and some distinct merges", () => {
+        const command = { ...cmd, target: target("A1:A3,E1:F2") };
+        const result = transform(command, { ...addMerge, target: target("A2:A4,G1:G2") });
+        expect(result).toEqual({ ...cmd, target: target("E1:F2") });
+      });
       test("two overlapping merges in different sheets", () => {
         const command = { ...cmd, target: target("C3:D5"), sheetId: "another sheet" };
         const result = transform(command, addMerge);