fix: BE protection for empty stickiness (#3615)

Add 'default' when creating or throw error when updating a
flexibleRollout strategy with empty stickiness
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---------

Signed-off-by: andreas-unleash <andreas@getunleash.ai>

src/lib/services/feature-toggle-service.ts

@@ -224,6 +224,16 @@ class FeatureToggleService {
                 'You can not change the featureName for an activation strategy.',
             );
         }
+
+        if (
+            strategy.parameters &&
+            'stickiness' in strategy.parameters &&
+            strategy.parameters.stickiness === ''
+        ) {
+            throw new InvalidOperationError(
+                'You can not have an empty string for stickiness.',
+            );
+        }
     }
 
     async validateProjectCanAccessSegments(
@@ -410,6 +420,14 @@ class FeatureToggleService {
             );
         }
 
+        if (
+            strategyConfig.parameters &&
+            'stickiness' in strategyConfig.parameters &&
+            strategyConfig.parameters.stickiness === ''
+        ) {
+            strategyConfig.parameters.stickiness = 'default';
+        }
+
         try {
             const newFeatureStrategy =
                 await this.featureStrategiesStore.createStrategyFeatureEnv({

src/test/e2e/api/admin/feature.e2e.test.ts

@@ -17,8 +17,11 @@ let app: IUnleashTest;
 let db: ITestDb;
 
 const defaultStrategy = {
-    name: 'default',
-    parameters: {},
+    name: 'flexibleRollout',
+    parameters: {
+        rollout: '100',
+        stickiness: '',
+    },
     constraints: [],
 };
 
@@ -844,3 +847,77 @@ test('Can add and remove tags at the same time', async () => {
             expect(res.body.tags).toHaveLength(1);
         });
 });
+
+test('Should return "default" for stickiness when creating a flexibleRollout strategy with "" for stickiness', async () => {
+    const username = 'toggle-feature';
+    const feature = {
+        name: 'test-featureA',
+        description: 'the #1 feature',
+    };
+    const projectId = 'default';
+
+    await app.services.featureToggleServiceV2.createFeatureToggle(
+        projectId,
+        feature,
+        username,
+    );
+    await app.services.featureToggleServiceV2.createStrategy(
+        defaultStrategy,
+        { projectId, featureName: feature.name, environment: DEFAULT_ENV },
+        username,
+    );
+
+    await app.request
+        .get(
+            `/api/admin/projects/${projectId}/features/${feature.name}/environments/${DEFAULT_ENV}`,
+        )
+        .expect((res) => {
+            const toggle = res.body;
+            expect(toggle.strategies).toHaveLength(1);
+            expect(toggle.strategies[0].parameters.stickiness).toBe('default');
+        });
+
+    await app.request
+        .get(`/api/admin/features/${feature.name}`)
+        .expect((res) => {
+            const toggle = res.body;
+            expect(toggle.strategies).toHaveLength(1);
+            expect(toggle.strategies[0].parameters.stickiness).toBe('default');
+        });
+});
+
+test('Should throw error when updating a flexibleRollout strategy with "" for stickiness', async () => {
+    const username = 'toggle-feature';
+    const feature = {
+        name: 'test-featureB',
+        description: 'the #1 feature',
+    };
+    const projectId = 'default';
+
+    await app.services.featureToggleServiceV2.createFeatureToggle(
+        projectId,
+        feature,
+        username,
+    );
+    await app.services.featureToggleServiceV2.createStrategy(
+        defaultStrategy,
+        { projectId, featureName: feature.name, environment: DEFAULT_ENV },
+        username,
+    );
+
+    const featureToggle =
+        await app.services.featureToggleServiceV2.getFeatureToggle(
+            feature.name,
+        );
+
+    await app.request
+        .patch(
+            `/api/admin/projects/${projectId}/features/${feature.name}/environments/${DEFAULT_ENV}/strategies/${featureToggle.environments[0].strategies[0].id}`,
+        )
+        .send(defaultStrategy)
+        .expect((res) => {
+            const result = res.body;
+            expect(res.status).toBe(400);
+            expect(result.error).toBe('Request validation failed');
+        });
+});