[AI-FSSDK] [FSSDK-12369] Add local holdouts support to JavaScript SDK

Author: Mat001

lib/core/decision_service/index.spec.ts

@@ -2879,4 +2879,190 @@ describe('DecisionService', () => {
       expect(variation).toBe(null);
     });
   });
+
+  // Level 2 decision service tests for local holdouts (FSSDK-12369)
+  // One test per branch of the pseudocode in Step 3 of the ticket.
+  describe('local holdouts (FSSDK-12369)', () => {
+    // Helper: build a datafile that has a local holdout targeting a specific experiment or delivery rule.
+    const makeLocalHoldoutDatafile = (targetRuleId: string, ruleIds: string[] = [targetRuleId]) => {
+      const datafile = getDecisionTestDatafile();
+      (datafile as any).holdouts = [
+        {
+          id: 'local_holdout_id',
+          key: 'local_holdout',
+          status: 'Running',
+          includedFlags: [],
+          excludedFlags: [],
+          includedRules: ruleIds,
+          audienceIds: [],
+          audienceConditions: [],
+          variations: [
+            {
+              id: 'local_holdout_variation_id',
+              key: 'local_holdout_variation',
+              variables: []
+            }
+          ],
+          trafficAllocation: [
+            { entityId: 'local_holdout_variation_id', endOfRange: 10000 }
+          ]
+        }
+      ];
+      return datafile;
+    };
+
+    beforeEach(() => {
+      mockBucket.mockReset();
+    });
+
+    it('global holdout branch: global holdout is evaluated before per-rule logic', async () => {
+      const datafile = getDecisionTestDatafile();
+      (datafile as any).holdouts = [
+        {
+          id: 'global_holdout_id',
+          key: 'global_holdout',
+          status: 'Running',
+          includedFlags: [],
+          excludedFlags: [],
+          // No includedRules → global holdout
+          audienceIds: [],
+          audienceConditions: [],
+          variations: [
+            { id: 'global_holdout_var_id', key: 'global_holdout_var', variables: [] }
+          ],
+          trafficAllocation: [{ entityId: 'global_holdout_var_id', endOfRange: 10000 }]
+        }
+      ];
+      const config = createProjectConfig(datafile);
+      const { decisionService } = getDecisionService();
+
+      // bucket returns the global holdout variation for the holdout, nothing for experiments
+      mockBucket.mockImplementation((params: BucketerParams) => {
+        if (params.experimentId === 'global_holdout_id') {
+          return { result: 'global_holdout_var_id', reasons: [] };
+        }
+        return { result: null, reasons: [] };
+      });
+
+      const user = new OptimizelyUserContext({ optimizely: {} as any, userId: 'user1' });
+      const feature = config.featureKeyMap['flag_1'];
+      const value = await decisionService.resolveVariationsForFeatureList('async', config, [feature], user, {}).get();
+
+      // Decision should be from the global holdout, not from any experiment
+      expect(value[0].result.decisionSource).toBe(DECISION_SOURCES.HOLDOUT);
+      expect(value[0].result.experiment?.id).toBe('global_holdout_id');
+    });
+
+    it('local holdout hit branch: user bucketed into local holdout for experiment rule returns holdout variation; audience and traffic not evaluated for that rule', async () => {
+      // exp_1 has id '2001'
+      const config = createProjectConfig(makeLocalHoldoutDatafile('2001'));
+      const { decisionService } = getDecisionService();
+
+      // bucket returns holdout variation when evaluating the local holdout
+      mockBucket.mockImplementation((params: BucketerParams) => {
+        if (params.experimentId === 'local_holdout_id') {
+          return { result: 'local_holdout_variation_id', reasons: [] };
+        }
+        return { result: null, reasons: [] };
+      });
+
+      const user = new OptimizelyUserContext({ optimizely: {} as any, userId: 'user1' });
+      const feature = config.featureKeyMap['flag_1'];
+      const value = await decisionService.resolveVariationsForFeatureList('async', config, [feature], user, {}).get();
+
+      // Should return holdout decision for the local holdout
+      expect(value[0].result.decisionSource).toBe(DECISION_SOURCES.HOLDOUT);
+      expect(value[0].result.experiment?.id).toBe('local_holdout_id');
+      expect(value[0].result.variation?.id).toBe('local_holdout_variation_id');
+    });
+
+    it('local holdout miss branch: user not bucketed into local holdout falls through to regular rule evaluation', async () => {
+      // exp_1 has id '2001' and audience 4001 (age <= 22)
+      const config = createProjectConfig(makeLocalHoldoutDatafile('2001'));
+      const { decisionService } = getDecisionService();
+
+      // bucket returns null for the local holdout, then succeeds for the experiment
+      mockBucket.mockImplementation((params: BucketerParams) => {
+        if (params.experimentId === 'local_holdout_id') {
+          return { result: null, reasons: [] };
+        }
+        if (params.experimentId === '2001') {
+          return { result: '5001', reasons: [] }; // variation_1 in exp_1
+        }
+        return { result: null, reasons: [] };
+      });
+
+      const user = new OptimizelyUserContext({
+        optimizely: {} as any,
+        userId: 'user1',
+        attributes: { age: 15 }, // satisfies 4001 audience (age <= 22)
+      });
+      const feature = config.featureKeyMap['flag_1'];
+      const value = await decisionService.resolveVariationsForFeatureList('async', config, [feature], user, {}).get();
+
+      // Should fall through to experiment evaluation (not holdout)
+      expect(value[0].result.decisionSource).toBe(DECISION_SOURCES.FEATURE_TEST);
+      expect(value[0].result.variation?.id).toBe('5001');
+    });
+
+    it('rule specificity: local holdout targeting experiment rule X does not affect experiment rule Y', async () => {
+      // exp_1 = '2001', exp_2 = '2002'. Local holdout targets only '2002' (exp_2).
+      // Audience for exp_1: 4001 (age <= 22). User satisfies exp_1 audience but not exp_2.
+      const config = createProjectConfig(makeLocalHoldoutDatafile('2002'));
+      const { decisionService } = getDecisionService();
+
+      // bucket returns holdout variation only for the local holdout when evaluating for '2002',
+      // and returns experiment variation for '2001'
+      mockBucket.mockImplementation((params: BucketerParams) => {
+        if (params.experimentId === 'local_holdout_id') {
+          return { result: 'local_holdout_variation_id', reasons: [] };
+        }
+        if (params.experimentId === '2001') {
+          return { result: '5001', reasons: [] };
+        }
+        return { result: null, reasons: [] };
+      });
+
+      // User satisfies exp_1 audience (age <= 22)
+      const user = new OptimizelyUserContext({
+        optimizely: {} as any,
+        userId: 'user1',
+        attributes: { age: 15 },
+      });
+      const feature = config.featureKeyMap['flag_1'];
+      const value = await decisionService.resolveVariationsForFeatureList('async', config, [feature], user, {}).get();
+
+      // exp_1 is evaluated first; local holdout targets '2002' not '2001', so exp_1 is evaluated normally
+      expect(value[0].result.decisionSource).toBe(DECISION_SOURCES.FEATURE_TEST);
+      expect(value[0].result.experiment?.id).toBe('2001');
+    });
+
+    it('local holdout applies to delivery rules (rollouts) as well as experiment rules', async () => {
+      // delivery_1 has id '3001'
+      const config = createProjectConfig(makeLocalHoldoutDatafile('3001'));
+      const { decisionService } = getDecisionService();
+
+      // bucket returns null for all experiments and the local holdout variation for delivery rule
+      mockBucket.mockImplementation((params: BucketerParams) => {
+        if (params.experimentId === 'local_holdout_id') {
+          return { result: 'local_holdout_variation_id', reasons: [] };
+        }
+        return { result: null, reasons: [] };
+      });
+
+      // No audience attributes → experiments won't match, falls through to rollout
+      const user = new OptimizelyUserContext({
+        optimizely: {} as any,
+        userId: 'user1',
+        attributes: { age: 15 }, // satisfies 4001 used by delivery_1
+      });
+      const feature = config.featureKeyMap['flag_1'];
+      const value = await decisionService.resolveVariationsForFeatureList('async', config, [feature], user, {}).get();
+
+      // Should be a holdout decision from the local holdout targeting the delivery rule
+      expect(value[0].result.decisionSource).toBe(DECISION_SOURCES.HOLDOUT);
+      expect(value[0].result.experiment?.id).toBe('local_holdout_id');
+    });
+  });
 });
+

lib/core/decision_service/index.ts

@@ -29,6 +29,8 @@ import {
   getVariationIdFromExperimentAndVariationKey,
   getVariationFromId,
   getVariationKeyFromId,
+  getGlobalHoldouts,
+  getHoldoutsForRule,
   isActive,
   ProjectConfig,
 } from '../../project_config/project_config';
@@ -135,6 +137,8 @@ interface DecisionServiceOptions {
 
 interface DeliveryRuleResponse<T, K> extends DecisionResponse<T> {
   skipToEveryoneElse: K;
+  /** Set when a local holdout was hit for this delivery rule (FSSDK-12369). */
+  localHoldoutDecision?: DecisionObj;
 }
 
 interface UserProfileTracker {
@@ -145,6 +149,12 @@ interface UserProfileTracker {
 type VarationKeyWithCmabParams = {
   variationKey?: string;
   cmabUuid?: string;
+  /**
+   * Set when the variation comes from a local holdout (FSSDK-12369).
+   * When present, the caller should use this as the full decision result
+   * instead of constructing one from the experiment.
+   */
+  localHoldoutDecision?: DecisionObj;
 };
 export type DecisionReason = [string, ...any[]];
 export type VariationResult = DecisionResponse<VarationKeyWithCmabParams>;
@@ -943,11 +953,11 @@ export class DecisionService {
       });
     }
 
-    // all global holouts should be evaluated for all flags
-    // global holdouts are available in configObj.holdouts
-    const { holdouts } = configObj;
+    // Global holdouts are evaluated at flag level, before any per-rule logic.
+    // getGlobalHoldouts() returns holdouts with includedRules == null/undefined.
+    const globalHoldouts = getGlobalHoldouts(configObj);
 
-    for (const holdout of holdouts) {
+    for (const holdout of globalHoldouts) {
       const holdoutDecision = this.getVariationForHoldout(configObj, holdout, user);
       decideReasons.push(...holdoutDecision.reasons);
 
@@ -1092,11 +1102,19 @@ export class DecisionService {
         });
       }
 
+      // If a local holdout was hit, return the holdout decision directly (preserves holdout as experiment).
+      if (decisionVariation.result.localHoldoutDecision) {
+        return Value.of(op, {
+          result: decisionVariation.result.localHoldoutDecision,
+          reasons: decideReasons,
+        });
+      }
+
       if(!decisionVariation.result.variationKey) {
         return this.traverseFeatureExperimentList(
           op, configObj, feature, fromIndex + 1, user, decideReasons, decideOptions, userProfileTracker);
       }
-  
+
       const variationKey = decisionVariation.result.variationKey;
       let variation: Variation | null = experiment.variationKeyMap[variationKey];
       if (!variation) {
@@ -1184,6 +1202,13 @@ export class DecisionService {
       variation = decisionVariation.result;
       skipToEveryoneElse = decisionVariation.skipToEveryoneElse;
       if (variation) {
+        // If a local holdout was hit for this delivery rule, use its decision object directly.
+        if (decisionVariation.localHoldoutDecision) {
+          return {
+            result: decisionVariation.localHoldoutDecision,
+            reasons: decideReasons,
+          };
+        }
         rolloutRule = configObj.experimentIdMap[rolloutRules[index].id];
         decisionObj = {
           experiment: rolloutRule,
@@ -1562,6 +1587,25 @@ export class DecisionService {
         reasons: decideReasons,
       });
     }
+
+    // Check local holdouts targeting this specific experiment rule (FSSDK-12369).
+    // Inserted immediately after the forced-decision block, before regular rule evaluation.
+    const localHoldoutsForExperiment = getHoldoutsForRule(configObj, rule.id);
+    for (const holdout of localHoldoutsForExperiment) {
+      const holdoutDecision = this.getVariationForHoldout(configObj, holdout, user);
+      decideReasons.push(...holdoutDecision.reasons);
+      if (holdoutDecision.result.variation) {
+        // Signal the caller to use the holdout decision directly, preserving the holdout as experiment.
+        return Value.of(op, {
+          result: {
+            variationKey: holdoutDecision.result.variation.key,
+            localHoldoutDecision: holdoutDecision.result,
+          },
+          reasons: decideReasons,
+        });
+      }
+    }
+
     const decisionVariationValue = this.resolveVariation(op, configObj, rule, user, decideOptions, userProfileTracker);
 
     return decisionVariationValue.then((variationResult) => {
@@ -1608,6 +1652,22 @@ export class DecisionService {
       };
     }
 
+    // Check local holdouts targeting this specific delivery rule (FSSDK-12369).
+    // Inserted immediately after the forced-decision block, before audience and traffic allocation checks.
+    const localHoldoutsForDelivery = getHoldoutsForRule(configObj, rule.id);
+    for (const holdout of localHoldoutsForDelivery) {
+      const holdoutDecision = this.getVariationForHoldout(configObj, holdout, user);
+      decideReasons.push(...holdoutDecision.reasons);
+      if (holdoutDecision.result.variation) {
+        return {
+          result: holdoutDecision.result.variation,
+          reasons: decideReasons,
+          skipToEveryoneElse,
+          localHoldoutDecision: holdoutDecision.result,
+        };
+      }
+    }
+
     const userId = user.getUserId();
     const attributes = user.getAttributes();
     const bucketingId = this.getBucketingId(userId, attributes);