Merge tree: add sidedness to obliterate ops in conflict farm tests (#…

…22747)

Functionally the same as #22615, but on a clean branch. 


[AB#15963](https://dev.azure.com/fluidframework/235294da-091d-4c29-84fc-cdfc3d90890b/_workitems/edit/15963)

packages/dds/merge-tree/src/test/client.conflictFarm.spec.ts

@@ -75,17 +75,30 @@ function runConflictFarmTests(opts: IConflictFarmConfig, extraSeed?: number): vo
 				config: { ...opts, applyOpDuringGeneration: true },
 			},
 			{
-				name: "with obliterate",
+				name: "obliterate with number endpoints",
 				config: {
 					...opts,
 					operations: [...opts.operations, obliterateRange],
 				},
 			},
+			// TODO: AB#15630
+			// {
+			// 	name: "obliterate with sided endpoints",
+			// 	config: {
+			// 		...opts,
+			// 		operations: [...opts.operations, obliterateRange, obliterateRangeSided],
+			// 	},
+			// },
 		])
 			it(`${name}: ConflictFarm_${minLength}`, async () => {
 				const random = makeRandom(0xdeadbeef, 0xfeedbed, minLength, extraSeed ?? 0);
 
-				const clients: TestClient[] = [new TestClient({ mergeTreeEnableObliterate: true })];
+				const clients: TestClient[] = [
+					new TestClient({
+						mergeTreeEnableObliterate: true,
+						mergeTreeEnableSidedObliterate: true,
+					}),
+				];
 				for (const [i, c] of clients.entries()) c.startOrUpdateCollaboration(clientNames[i]);
 
 				let seq = 0;

packages/dds/merge-tree/src/test/mergeTreeOperationRunner.ts

@@ -14,6 +14,7 @@ import { ISequencedDocumentMessage } from "@fluidframework/driver-definitions/in
 import { walkAllChildSegments } from "../mergeTreeNodeWalk.js";
 import { ISegment, SegmentGroup, toMoveInfo, toRemovalInfo } from "../mergeTreeNodes.js";
 import { IMergeTreeOp, MergeTreeDeltaType, ReferenceType } from "../ops.js";
+import { Side } from "../sequencePlace.js";
 import { TextSegment } from "../textSegment.js";
 
 import { _dirname } from "./dirname.cjs";
@@ -39,6 +40,32 @@ export const obliterateRange: TestOperation = (
 	opEnd: number,
 ) => client.obliterateRangeLocal(opStart, opEnd);
 
+export const obliterateRangeSided: TestOperation = (
+	client: TestClient,
+	opStart: number,
+	opEnd: number,
+	random: IRandom,
+) => {
+	let startSide: Side;
+	let endSide: Side;
+
+	const oblEnd = random.integer(opStart, client.getLength() - 1);
+	// TODO: to create zero length obliterate ops, change '<=' to '<'.
+	// Doing so may cause different failures than those without zero length.
+	// AB#19930
+	if (oblEnd - opStart <= 1) {
+		startSide = Side.Before;
+		endSide = Side.After;
+	} else {
+		startSide = random.pick([Side.Before, Side.After]);
+		endSide = random.pick([Side.Before, Side.After]);
+	}
+
+	const start = { pos: opStart, side: startSide };
+	const end = { pos: oblEnd, side: endSide };
+	return client.obliterateRangeLocal(start, end);
+};
+
 export const annotateRange: TestOperation = (
 	client: TestClient,
 	opStart: number,