Detect changes in AB Testing (ABT) experiment metadata during config fetch

firebase-config/CHANGELOG.md

@@ -1,5 +1,7 @@
 # Unreleased
 
+- [fixed] Realtime support for A/B test updates
+
 # 23.0.1
 
 - [changed] Bumped internal dependencies.

firebase-config/src/main/java/com/google/firebase/remoteconfig/RemoteConfigConstants.java

@@ -97,12 +97,14 @@ public final class RemoteConfigConstants {
    */
   @StringDef({
     ExperimentDescriptionFieldKey.EXPERIMENT_ID,
-    ExperimentDescriptionFieldKey.VARIANT_ID
+    ExperimentDescriptionFieldKey.VARIANT_ID,
+    ExperimentDescriptionFieldKey.AFFECTED_PARAMETER_KEYS
   })
   @Retention(RetentionPolicy.SOURCE)
   public @interface ExperimentDescriptionFieldKey {
     String EXPERIMENT_ID = "experimentId";
     String VARIANT_ID = "variantId";
+    String AFFECTED_PARAMETER_KEYS = "affectedParameterKeys";
   }
 
   private RemoteConfigConstants() {}

firebase-config/src/main/java/com/google/firebase/remoteconfig/internal/ConfigContainer.java

@@ -14,6 +14,9 @@
 
 package com.google.firebase.remoteconfig.internal;
 
+import static com.google.firebase.remoteconfig.RemoteConfigConstants.ExperimentDescriptionFieldKey.AFFECTED_PARAMETER_KEYS;
+import static com.google.firebase.remoteconfig.RemoteConfigConstants.ExperimentDescriptionFieldKey.EXPERIMENT_ID;
+
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Date;
 import java.util.HashMap;
@@ -37,6 +40,7 @@ public class ConfigContainer {
   static final String ABT_EXPERIMENTS_KEY = "abt_experiments_key";
   static final String PERSONALIZATION_METADATA_KEY = "personalization_metadata_key";
   static final String TEMPLATE_VERSION_NUMBER_KEY = "template_version_number_key";
+  static final String ROLLOUT_ID_PREFIX = "rollout";
   static final String ROLLOUT_METADATA_KEY = "rollout_metadata_key";
   public static final String ROLLOUT_METADATA_AFFECTED_KEYS = "affectedParameterKeys";
   public static final String ROLLOUT_METADATA_ID = "rolloutId";
@@ -220,6 +224,31 @@ private Map<String, Map<String, String>> createRolloutParameterKeyMap() throws J
     return rolloutMetadataMap;
   }
 
+  /** Creates a map where the key is the config key and the value is the experiment description. */
+  private Map<String, JSONObject> createExperimentsMap() throws JSONException {
+    Map<String, JSONObject> experimentsMap = new HashMap<>();
+    JSONArray abtExperiments = this.getAbtExperiments();
+    // Iterate through all experiments to check if it has the `affectedParameterKeys` field.
+    for (int i = 0; i < abtExperiments.length(); i++) {
+      JSONObject experiment = abtExperiments.getJSONObject(i);
+      if (!experiment.has(AFFECTED_PARAMETER_KEYS)
+          || experiment.getString(EXPERIMENT_ID).startsWith(ROLLOUT_ID_PREFIX)) {
+        continue;
+      }
+
+      // Since a config key can only have one experiment associated with it, map the key to the
+      // experiment.
+      JSONArray affectedKeys = experiment.getJSONArray(AFFECTED_PARAMETER_KEYS);
+      for (int j = 0; j < affectedKeys.length(); j++) {
+        String key = affectedKeys.getString(j);
+        JSONObject experimentsCopy = new JSONObject(experiment.toString());
+        experimentsMap.put(key, experimentsCopy);
+      }
+    }
+
+    return experimentsMap;
+  }
+
   /**
    * @param other The other {@link ConfigContainer} against which to compute the diff
    * @return The set of config keys that have changed between the this config and {@code other}
@@ -233,6 +262,10 @@ public Set<String> getChangedParams(ConfigContainer other) throws JSONException
     Map<String, Map<String, String>> rolloutMetadataMap = this.createRolloutParameterKeyMap();
     Map<String, Map<String, String>> otherRolloutMetadataMap = other.createRolloutParameterKeyMap();
 
+    // Config key to experiments map.
+    Map<String, JSONObject> experimentsMap = this.createExperimentsMap();
+    Map<String, JSONObject> otherExperimentsMap = other.createExperimentsMap();
+
     Set<String> changed = new HashSet<>();
     Iterator<String> keys = this.getConfigs().keys();
     while (keys.hasNext()) {
@@ -284,6 +317,20 @@ public Set<String> getChangedParams(ConfigContainer other) throws JSONException
         continue;
       }
 
+      // If one and only one of the experiments map contains the key, add it to changed.
+      if (experimentsMap.containsKey(key) != otherExperimentsMap.containsKey(key)) {
+        changed.add(key);
+        continue;
+      }
+
+      // If both experiment maps contains the key, compare the experiments to see if it's different.
+      if (otherExperimentsMap.containsKey(key)
+          && experimentsMap.containsKey(key)
+          && !otherExperimentsMap.get(key).toString().equals(experimentsMap.get(key).toString())) {
+        changed.add(key);
+        continue;
+      }
+
       // Since the key is the same in both configs, remove it from otherConfig
       otherConfig.remove(key);
     }

firebase-config/src/test/java/com/google/firebase/remoteconfig/internal/ConfigContainerTest.java

@@ -15,6 +15,7 @@
 package com.google.firebase.remoteconfig.internal;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.firebase.remoteconfig.RemoteConfigConstants.ExperimentDescriptionFieldKey.AFFECTED_PARAMETER_KEYS;
 import static com.google.firebase.remoteconfig.RemoteConfigConstants.ExperimentDescriptionFieldKey.EXPERIMENT_ID;
 import static com.google.firebase.remoteconfig.RemoteConfigConstants.ExperimentDescriptionFieldKey.VARIANT_ID;
 import static com.google.firebase.remoteconfig.internal.Personalization.ARM_INDEX;
@@ -138,23 +139,102 @@ public void getChangedParams_sameP13nMetadata_returnsEmptySet() throws Exception
   }
 
   @Test
-  public void getChangedParams_changedExperimentsMetadata_returnsNoParamKeys() throws Exception {
+  public void getChangedParams_sameExperimentsMetadata_returnsEmptySet() throws Exception {
+    JSONArray activeExperiments = generateAbtExperiments(1);
+    JSONArray fetchedExperiments = generateAbtExperiments(1);
+
     ConfigContainer config =
         ConfigContainer.newBuilder()
-            .replaceConfigsWith(ImmutableMap.of("string_param", "value_1"))
+            .replaceConfigsWith(ImmutableMap.of("abt_test_key_1", "value_1"))
+            .withAbtExperiments(activeExperiments)
             .build();
 
     ConfigContainer other =
         ConfigContainer.newBuilder()
-            .replaceConfigsWith(ImmutableMap.of("string_param", "value_1"))
-            .withAbtExperiments(generateAbtExperiments(1))
+            .replaceConfigsWith(ImmutableMap.of("abt_test_key_1", "value_1"))
+            .withAbtExperiments(fetchedExperiments)
             .build();
 
     Set<String> changedParams = config.getChangedParams(other);
 
     assertThat(changedParams).isEmpty();
   }
 
+  @Test
+  public void getChangedParams_changedExperimentsMetadata_returnsUpdatedKey() throws Exception {
+    JSONArray activeExperiments = generateAbtExperiments(1);
+    JSONArray fetchedExperiments = generateAbtExperiments(1);
+
+    activeExperiments.getJSONObject(0).put(VARIANT_ID, "32");
+
+    ConfigContainer config =
+        ConfigContainer.newBuilder()
+            .replaceConfigsWith(ImmutableMap.of("abt_test_key_1", "value_1"))
+            .withAbtExperiments(activeExperiments)
+            .build();
+
+    ConfigContainer other =
+        ConfigContainer.newBuilder()
+            .replaceConfigsWith(ImmutableMap.of("abt_test_key_1", "value_1"))
+            .withAbtExperiments(fetchedExperiments)
+            .build();
+
+    Set<String> changedParams = config.getChangedParams(other);
+
+    assertThat(changedParams).containsExactly("abt_test_key_1");
+  }
+
+  @Test
+  public void getChangedParams_deletedExperiment_returnsUpdatedKey() throws Exception {
+    JSONArray activeExperiments = generateAbtExperiments(1);
+    JSONArray fetchedExperiments = new JSONArray();
+
+    ConfigContainer config =
+        ConfigContainer.newBuilder()
+            .replaceConfigsWith(ImmutableMap.of("abt_test_key_1", "value_1"))
+            .withAbtExperiments(activeExperiments)
+            .build();
+
+    ConfigContainer other =
+        ConfigContainer.newBuilder()
+            .replaceConfigsWith(ImmutableMap.of("abt_test_key_1", "value_1"))
+            .withAbtExperiments(fetchedExperiments)
+            .build();
+
+    Set<String> changedParams = config.getChangedParams(other);
+
+    assertThat(changedParams).containsExactly("abt_test_key_1");
+  }
+
+  @Test
+  public void getChangedParams_changedExperimentsKeys_returnsUpdatedKey() throws Exception {
+    JSONArray activeExperiments = generateAbtExperiments(1);
+    JSONArray fetchedExperiments = generateAbtExperiments(1);
+
+    fetchedExperiments
+        .getJSONObject(0)
+        .getJSONArray(AFFECTED_PARAMETER_KEYS)
+        .put(0, "abt_test_key_2");
+
+    ConfigContainer config =
+        ConfigContainer.newBuilder()
+            .replaceConfigsWith(
+                ImmutableMap.of("abt_test_key_1", "value_1", "abt_test_key_2", "value_2"))
+            .withAbtExperiments(activeExperiments)
+            .build();
+
+    ConfigContainer other =
+        ConfigContainer.newBuilder()
+            .replaceConfigsWith(
+                ImmutableMap.of("abt_test_key_1", "value_1", "abt_test_key_2", "value_2"))
+            .withAbtExperiments(fetchedExperiments)
+            .build();
+
+    Set<String> changedParams = config.getChangedParams(other);
+
+    assertThat(changedParams).containsExactly("abt_test_key_1", "abt_test_key_2");
+  }
+
   @Test
   public void getChangedParams_noChanges_returnsEmptySet() throws Exception {
     ConfigContainer config =
@@ -452,9 +532,14 @@ public void getChangedParams_unchangedRolloutMetadata_returnsNoKey() throws Exce
 
   private static JSONArray generateAbtExperiments(int numExperiments) throws JSONException {
     JSONArray experiments = new JSONArray();
+    JSONArray experimentKeys = new JSONArray();
+    experimentKeys.put("abt_test_key_1");
     for (int experimentNum = 1; experimentNum <= numExperiments; experimentNum++) {
       experiments.put(
-          new JSONObject().put(EXPERIMENT_ID, "exp" + experimentNum).put(VARIANT_ID, "var1"));
+          new JSONObject()
+              .put(EXPERIMENT_ID, "exp_" + experimentNum)
+              .put(VARIANT_ID, "var1")
+              .put(AFFECTED_PARAMETER_KEYS, experimentKeys));
     }
     return experiments;
   }