Assign new AB tests to MVT ids randomly

ab-testing/config/abTests.ts

@@ -209,7 +209,6 @@ const ABTests: ABTest[] = [
 		groups: ["a", "b"],
 		shouldForceMetricsCollection: false,
 	},
-
 	{
 		name: "commercial-prebid-failsafe-timeout",
 		description:
@@ -223,6 +222,30 @@ const ABTests: ABTest[] = [
 		groups: ["control", "variant"],
 		shouldForceMetricsCollection: true,
 	},
+	{
+		name: "webx-test-test",
+		description: "Test for webx test",
+		owners: ["dotcom.platform@theguardian.com"],
+		status: "ON",
+		expirationDate: "2026-08-31",
+		type: "client",
+		audienceSize: 10 / 100,
+		audienceSpace: "D",
+		groups: ["control", "variant"],
+		shouldForceMetricsCollection: false,
+	},
+	{
+		name: "webx-test-test-2",
+		description: "Test for webx test",
+		owners: ["dotcom.platform@theguardian.com"],
+		status: "ON",
+		expirationDate: "2026-08-31",
+		type: "client",
+		audienceSize: 50 / 100,
+		audienceSpace: "E",
+		groups: ["control", "variant"],
+		shouldForceMetricsCollection: false,
+	},
 ];
 
 const activeABtests = ABTests.filter((test) => test.status === "ON");

ab-testing/config/lib/types.ts

@@ -1,6 +1,6 @@
 type FastlyTestParams = { name: string; type: string; exp: number };
 type AudienceSpace = Map<string, FastlyTestParams>;
 
-type AllSpace = Map<string, FastlyTestParams[]>;
+type AllSpaces = Map<string, FastlyTestParams[]>;
 
-export type { FastlyTestParams, AudienceSpace, AllSpace };
+export type { FastlyTestParams, AudienceSpace, AllSpaces as AllSpace };

ab-testing/config/scripts/build/calculate-mvt-updates.ts

@@ -104,7 +104,7 @@ const calculateAllSpaceUpdates = (
 	mvtGroups: AllSpace,
 	tests: ABTest[],
 ): AllSpace => {
-	const updatedTestSpace: AudienceSpace[] = AudienceSpaces.map((space, i) => {
+	const updatedTestSpaces: AudienceSpace[] = AudienceSpaces.map((space) => {
 		console.log(`Calculating updates for space: ${space}`);
 		const spaceTests = tests.filter(
 			(test) => (test.audienceSpace ?? "A") === space, // 'A' is the default space
@@ -116,15 +116,24 @@ const calculateAllSpaceUpdates = (
 		}
 
 		const spaceMVTGroups = new Map(
-			mvtGroups
-				.entries()
-				.map(([key, value]) => [key, value[i] as FastlyTestParams]),
+			Array.from(mvtGroups.entries())
+				.map(([mvtId, tests]) => [
+					mvtId,
+					spaceTests.find((test) =>
+						tests.find(
+							(t) => t.name === test.name && t.type === test.type,
+						),
+					),
+				])
+				.filter(([, test]) => test !== undefined) as Array<
+				[string, FastlyTestParams]
+			>,
 		);
 
 		return calculateSpaceUpdates(spaceMVTGroups, spaceTests);
 	});
 
-	return updatedTestSpace.reduce((acc, curr) => {
+	return updatedTestSpaces.reduce((acc, curr) => {
 		curr.forEach((value, key) => {
 			if (!acc.has(key)) {
 				acc.set(key, []);

ab-testing/config/scripts/build/test-group-mvt-manager.ts

@@ -47,9 +47,13 @@ class TestGroupMVTManager {
 			Array.from(this.testGroups.values()).flat(),
 		);
 
+		/**
+		 * collect all available MVTs that are not currently occupied in a random order
+		 * so that new test mvts are assigned randomly.
+		 */
 		this.availableMVTs = Array.from({ length: MVT_COUNT }, (_, i) => i)
 			.filter((i) => !this.occupiedMVTs.has(i))
-			.sort((a, b) => a - b);
+			.sort(() => Math.random() - 0.5);
 
 		console.log(
 			`Initialized TestGroupMVTs with ${this.availableMVTs.length} available MVTs`,
@@ -109,11 +113,14 @@ class TestGroupMVTManager {
 				throw new Error(`Not enough available MVTs for test ${name}`);
 			}
 			for (let i = 0; i < additionalMVTsNeeded; i++) {
-				const mvtIndex = this.availableMVTs.shift();
-				if (mvtIndex !== undefined) {
-					currentMVTs.push(mvtIndex);
-					this.occupiedMVTs.add(mvtIndex);
+				const mvtId = this.availableMVTs.shift();
+				if (mvtId === undefined) {
+					throw new Error(
+						`No available MVTs left to expand test ${name}`,
+					);
 				}
+				currentMVTs.push(mvtId);
+				this.occupiedMVTs.add(mvtId);
 			}
 		} else if (newSize < currentSize) {
 			const removedMVTs = currentMVTs.slice(newSize);
@@ -122,8 +129,6 @@ class TestGroupMVTManager {
 				this.availableMVTs.push(mvt);
 			});
 			currentMVTs.length = newSize;
-			// Keep available MVTs sorted in ascending order
-			this.availableMVTs.sort((a, b) => a - b);
 		}
 		this.testGroups.set(name, currentMVTs);
 	}
@@ -140,8 +145,6 @@ class TestGroupMVTManager {
 				this.availableMVTs.push(mvt);
 			});
 			this.testGroups.delete(name);
-			// Keep available MVTs sorted in ascending order
-			this.availableMVTs.sort((a, b) => a - b);
 		}
 	}
 }