update rollouts to re-evaluate enrollment if they are disqualified for targeting or bucketing

CHANGELOG.md

@@ -21,7 +21,7 @@
 
 ### 🦊 What's Changed 🦊
 
-- When a rollout audience size decreases, the enrollment is re-evaluated and the client is unenrolled if no longer in the bucket. ([#5687](https://github.com/mozilla/application-services/pull/5687)).
+- When a rollout audience size changes, the enrollment is re-evaluated and the client is un-enrolled if no longer in the bucket or re-enrolled if they had previously been disqualified from bucketing. ([#5687](https://github.com/mozilla/application-services/pull/5687), [#5716](https://github.com/mozilla/application-services/pull/5716)).
   - The record of enrollment will be available in the new `enrollments` targeting attribute.
 - Add `enrollments` value to `TargetingAttributes` — it is a set of strings containing all enrollments, past and present ([#5685](https://github.com/mozilla/application-services/pull/5685)).
   - _Note: This change only applies to stateful uses of the Nimbus SDK, e.g. mobile_

components/nimbus/src/enrollment.rs

@@ -71,6 +71,8 @@ pub enum DisqualifiedReason {
     OptOut,
     /// The targeting has changed for an experiment.
     NotTargeted,
+    /// The bucketing has changed for an experiment.
+    NotSelected,
 }
 
 // Every experiment has an ExperimentEnrollment, even when we aren't enrolled.
@@ -167,7 +169,7 @@ impl ExperimentEnrollment {
         targeting_helper: &NimbusTargetingHelper,
         out_enrollment_events: &mut Vec<EnrollmentChangeEvent>,
     ) -> Result<Self> {
-        Ok(match self.status {
+        Ok(match &self.status {
             EnrollmentStatus::NotEnrolled { .. } | EnrollmentStatus::Error { .. } => {
                 if !is_user_participating || updated_experiment.is_enrollment_paused {
                     self.clone()
@@ -190,6 +192,7 @@ impl ExperimentEnrollment {
                     updated_enrollment
                 }
             }
+
             EnrollmentStatus::Enrolled {
                 ref branch,
                 ref reason,
@@ -240,10 +243,12 @@ impl ExperimentEnrollment {
                         EnrollmentStatus::NotEnrolled {
                             reason: NotEnrolledReason::NotSelected,
                         } => {
-                            // In the case of a rollout being scaled back, we should end with WasEnrolled.
+                            // In the case of a rollout being scaled back, we should be disqualified with NotSelected.
                             //
-                            self.on_experiment_ended(out_enrollment_events)
-                                .ok_or_else(|| NimbusError::InternalError("An unexpected None happened while ending an experiment prematurely"))?
+                            let updated_enrollment =
+                                self.disqualify_from_enrolled(DisqualifiedReason::NotSelected);
+                            out_enrollment_events.push(updated_enrollment.get_change_event());
+                            updated_enrollment
                         }
                         EnrollmentStatus::NotEnrolled { .. }
                         | EnrollmentStatus::Enrolled { .. }
@@ -255,6 +260,7 @@ impl ExperimentEnrollment {
             EnrollmentStatus::Disqualified {
                 ref branch,
                 enrollment_id,
+                reason,
                 ..
             } => {
                 if !is_user_participating {
@@ -266,10 +272,26 @@ impl ExperimentEnrollment {
                         slug: self.slug.clone(),
                         status: EnrollmentStatus::Disqualified {
                             reason: DisqualifiedReason::OptOut,
-                            enrollment_id,
+                            enrollment_id: *enrollment_id,
                             branch: branch.clone(),
                         },
                     }
+                } else if updated_experiment.is_rollout
+                    && matches!(
+                        reason,
+                        DisqualifiedReason::NotSelected | DisqualifiedReason::NotTargeted,
+                    )
+                {
+                    let evaluated_enrollment = evaluate_enrollment(
+                        nimbus_id,
+                        available_randomization_units,
+                        updated_experiment,
+                        targeting_helper,
+                    )?;
+                    match evaluated_enrollment.status {
+                        EnrollmentStatus::Enrolled { .. } => evaluated_enrollment,
+                        _ => self.clone(),
+                    }
                 } else {
                     self.clone()
                 }
@@ -432,6 +454,7 @@ impl ExperimentEnrollment {
                 enrollment_id,
                 branch,
                 match reason {
+                    DisqualifiedReason::NotSelected => Some("bucketing"),
                     DisqualifiedReason::NotTargeted => Some("targeting"),
                     DisqualifiedReason::OptOut => Some("optout"),
                     DisqualifiedReason::Error => Some("error"),

components/nimbus/src/nimbus_client.rs

@@ -325,7 +325,7 @@ impl NimbusClient {
                     is_enrolled_set.insert(ee.slug.clone());
                     all_enrolled_set.insert(ee.slug.clone());
                 }
-                EnrollmentStatus::WasEnrolled { .. } => {
+                EnrollmentStatus::WasEnrolled { .. } | EnrollmentStatus::Disqualified { .. } => {
                     all_enrolled_set.insert(ee.slug.clone());
                 }
                 _ => {}

components/nimbus/src/tests/helpers.rs

@@ -9,6 +9,7 @@ use crate::{
     AppContext, EnrollmentStatus, Experiment, FeatureConfig, NimbusTargetingHelper,
     TargetingAttributes,
 };
+use serde::Serialize;
 use serde_json::{json, Value};
 use std::collections::HashSet;
 use uuid::Uuid;
@@ -385,3 +386,51 @@ pub fn get_multi_feature_experiment(
 pub fn no_coenrolling_features() -> HashSet<&'static str> {
     Default::default()
 }
+
+#[cfg_attr(not(feature = "stateful"), allow(unused))]
+pub fn to_local_experiments_string<S>(experiments: &[S]) -> crate::Result<String>
+where
+    S: Serialize,
+{
+    Ok(serde_json::to_string(&json!({ "data": experiments }))?)
+}
+
+#[cfg_attr(not(feature = "stateful"), allow(unused))]
+pub fn get_targeted_experiment(slug: &str, targeting: &str) -> serde_json::Value {
+    json!({
+        "schemaVersion": "1.0.0",
+        "slug": slug,
+        "endDate": null,
+        "featureIds": ["some-feature-1"],
+        "branches": [
+            {
+            "slug": "control",
+            "ratio": 1
+            },
+            {
+            "slug": "treatment",
+            "ratio": 1
+            }
+        ],
+        "channel": "nightly",
+        "probeSets": [],
+        "startDate": null,
+        "appName": "fenix",
+        "appId": "org.mozilla.fenix",
+        "bucketConfig": {
+            "count": 10000,
+            "start": 0,
+            "total": 10000,
+            "namespace": "secure-gold",
+            "randomizationUnit": "nimbus_id"
+        },
+        "targeting": targeting,
+        "userFacingName": "test experiment",
+        "referenceBranch": "control",
+        "isEnrollmentPaused": false,
+        "proposedEnrollment": 7,
+        "userFacingDescription": "This is a test experiment for testing purposes.",
+        "id": "secure-copper",
+        "last_modified": 1_602_197_324_372i64,
+    })
+}