Add experiment properties to feature flag exposure tracking

src/androidTest/java/com/mixpanel/android/mpmetrics/FeatureFlagManagerTest.java

@@ -303,6 +303,18 @@ private String createFlagsResponseJson(Map<String, MixpanelFlagVariant> flags) {
         } else {
           flagDef.put("variant_value", entry.getValue().value);
         }
+
+        // Add optional experiment parameters if they exist
+        if (entry.getValue().experimentID != null) {
+          flagDef.put("experiment_id", entry.getValue().experimentID);
+        }
+        if (entry.getValue().isExperimentActive != null) {
+          flagDef.put("is_experiment_active", entry.getValue().isExperimentActive);
+        }
+        if (entry.getValue().isQATester != null) {
+          flagDef.put("is_qa_tester", entry.getValue().isQATester);
+        }
+
         flagsObject.put(entry.getKey(), flagDef);
       }
       return new JSONObject().put("flags", flagsObject).toString();
@@ -1701,4 +1713,38 @@ public void testTimingUpperBoundValidation() throws InterruptedException, JSONEx
     // In practice, our test should complete much faster
     assertTrue("Test fetch should be fast in practice", fetchLatencyMs < 5000);
   }
+
+  @Test
+  public void testOptionalParametersInTracking_WithAllFields_ShouldIncludeInProperties() throws Exception {
+    // Create flag variant with all experiment parameters
+    Map<String, MixpanelFlagVariant> serverFlags = new HashMap<>();
+    serverFlags.put("test_tracking_flag", new MixpanelFlagVariant("variant_c", "tracking_value", "exp_789", true, true));
+
+    mMockRemoteService.addResponse(createFlagsResponseJson(serverFlags).getBytes(StandardCharsets.UTF_8));
+    mFeatureFlagManager.loadFlags();
+
+    // Wait for flags to be ready
+    for (int i = 0; i < 20 && !mFeatureFlagManager.areFlagsReady(); ++i) {
+      Thread.sleep(100);
+    }
+    assertTrue("Flags should be ready", mFeatureFlagManager.areFlagsReady());
+
+    // Setup tracking expectation
+    mMockDelegate.resetTrackCalls();
+    mMockDelegate.trackCalledLatch = new CountDownLatch(1);
+
+    // Get variant to trigger tracking
+    MixpanelFlagVariant fallback = new MixpanelFlagVariant("fallback", "fallback_value");
+    mFeatureFlagManager.getVariantSync("test_tracking_flag", fallback);
+
+    // Wait for tracking call
+    assertTrue("Track should be called", mMockDelegate.trackCalledLatch.await(5, TimeUnit.SECONDS));
+    assertEquals("Track should be called exactly once", 1, mMockDelegate.trackCalls.size());
+
+    // Verify tracking properties include optional parameters
+    MockFeatureFlagDelegate.TrackCall call = mMockDelegate.trackCalls.get(0);
+    assertEquals("ExperimentID should be included", "exp_789", call.properties.getString("$experiment_id"));
+    assertTrue("IsExperimentActive should be included", call.properties.getBoolean("$is_experiment_active"));
+    assertTrue("IsQATester should be included", call.properties.getBoolean("$is_qa_tester"));
+  }
 }

src/main/java/com/mixpanel/android/mpmetrics/FeatureFlagManager.java

@@ -711,6 +711,16 @@ private void _performTrackingDelegateCall(String flagName, MixpanelFlagVariant v
         properties.put("timeLastFetched", timing.timeLastFetched);
         properties.put("fetchLatencyMs", timing.fetchLatencyMs);
       }
+
+      if (variant.experimentID != null) {
+        properties.put("$experiment_id", variant.experimentID);
+      }
+      if (variant.isExperimentActive != null) {
+        properties.put("$is_experiment_active", variant.isExperimentActive);
+      }
+      if (variant.isQATester != null) {
+        properties.put("$is_qa_tester", variant.isQATester);
+      }
     } catch (JSONException e) {
       MPLog.e(LOGTAG, "Failed to create JSON properties for $experiment_started event", e);
       return; // Don't track if properties failed

src/main/java/com/mixpanel/android/mpmetrics/MixpanelFlagVariant.java

@@ -26,7 +26,25 @@ public class MixpanelFlagVariant {
     public final Object value;
 
     /**
-     * Constructs a {@code FeatureFlagData} object when parsing an API response.
+     * The value of experimentID. This corresponds to the optional 'experiment_id' field in the Mixpanel API response.
+     */
+    @Nullable
+    public final String experimentID;
+
+    /**
+     * The value of isExperimentActive. This corresponds to the optional 'is_experiment_active' field in the Mixpanel API response.
+     */
+    @Nullable
+    public final Boolean isExperimentActive;
+
+    /**
+     * The value of isQATester. This corresponds to the optional 'is_qa_tester' field in the Mixpanel API response.
+     */
+    @Nullable
+    public final Boolean isQATester;
+
+    /**
+     * Constructs a {@code MixpanelFlagVariant} object when parsing an API response.
      *
      * @param key The key of the feature flag variant. Corresponds to 'variant_key' from the API. Cannot be null.
      * @param value The value of the feature flag variant. Corresponds to 'variant_value' from the API.
@@ -35,10 +53,31 @@ public class MixpanelFlagVariant {
     public MixpanelFlagVariant(@NonNull String key, @Nullable Object value) {
         this.key = key;
         this.value = value;
+        this.experimentID = null;
+        this.isExperimentActive = null;
+        this.isQATester = null;
+    }
+
+    /**
+     * Constructs a {@code MixpanelFlagVariant} object when parsing an API response with optional experiment fields.
+     *
+     * @param key The key of the feature flag variant. Corresponds to 'variant_key' from the API. Cannot be null.
+     * @param value The value of the feature flag variant. Corresponds to 'variant_value' from the API.
+     * Can be Boolean, String, Number, JSONArray, JSONObject, or null.
+     * @param experimentID The experiment ID. Corresponds to 'experiment_id' from the API. Can be null.
+     * @param isExperimentActive Whether the experiment is active. Corresponds to 'is_experiment_active' from the API. Can be null.
+     * @param isQATester Whether the user is a QA tester. Corresponds to 'is_qa_tester' from the API. Can be null.
+     */
+    public MixpanelFlagVariant(@NonNull String key, @Nullable Object value, @Nullable String experimentID, @Nullable Boolean isExperimentActive, @Nullable Boolean isQATester) {
+        this.key = key;
+        this.value = value;
+        this.experimentID = experimentID;
+        this.isExperimentActive = isExperimentActive;
+        this.isQATester = isQATester;
     }
 
     /**
-     * Constructs a {@code FeatureFlagData} object for creating fallback instances.
+     * Constructs a {@code MixpanelFlagVariant} object for creating fallback instances.
      * In this case, the provided {@code keyAndValue} is used as both the key and the value
      * for the feature flag data. This is typically used when a flag is not found
      * and a default string value needs to be returned.
@@ -48,10 +87,13 @@ public MixpanelFlagVariant(@NonNull String key, @Nullable Object value) {
     public MixpanelFlagVariant(@NonNull String keyAndValue) {
         this.key = keyAndValue; // Default key to the value itself
         this.value = keyAndValue;
+        this.experimentID = null;
+        this.isExperimentActive = null;
+        this.isQATester = null;
     }
 
     /**
-     * Constructs a {@code FeatureFlagData} object for creating fallback instances.
+     * Constructs a {@code MixpanelFlagVariant} object for creating fallback instances.
      * In this version, the key is set to an empty string (""), and the provided {@code value}
      * is used as the value for the feature flag data. This is typically used when a
      * flag is not found or an error occurs, and a default value needs to be provided.
@@ -62,15 +104,21 @@ public MixpanelFlagVariant(@NonNull String keyAndValue) {
     public MixpanelFlagVariant(@NonNull Object value) {
         this.key = "";
         this.value = value;
+        this.experimentID = null;
+        this.isExperimentActive = null;
+        this.isQATester = null;
     }
 
     /**
-     * Default constructor that initializes an empty {@code FeatureFlagData} object.
+     * Default constructor that initializes an empty {@code MixpanelFlagVariant} object.
      * The key is set to an empty string ("") and the value is set to null.
      * This constructor might be used internally or for specific default cases.
      */
     MixpanelFlagVariant() {
         this.key = "";
         this.value = null;
+        this.experimentID = null;
+        this.isExperimentActive = null;
+        this.isQATester = null;
     }
 }

src/main/java/com/mixpanel/android/util/JsonUtils.java

@@ -153,7 +153,23 @@ public static Map<String, MixpanelFlagVariant> parseFlagsResponse(@Nullable JSON
                         MPLog.w(LOGTAG, "Flag definition missing 'variant_value' for key: " + featureName + ". Assuming null value.");
                     }
 
-                    MixpanelFlagVariant flagData = new MixpanelFlagVariant(variantKey, variantValue);
+                    // Parse optional experiment tracking fields
+                    String experimentID = null;
+                    if (flagDefinition.has(MPConstants.Flags.EXPERIMENT_ID) && !flagDefinition.isNull(MPConstants.Flags.EXPERIMENT_ID)) {
+                        experimentID = flagDefinition.getString(MPConstants.Flags.EXPERIMENT_ID);
+                    }
+
+                    Boolean isExperimentActive = null;
+                    if (flagDefinition.has(MPConstants.Flags.IS_EXPERIMENT_ACTIVE) && !flagDefinition.isNull(MPConstants.Flags.IS_EXPERIMENT_ACTIVE)) {
+                        isExperimentActive = flagDefinition.getBoolean(MPConstants.Flags.IS_EXPERIMENT_ACTIVE);
+                    }
+
+                    Boolean isQATester = null;
+                    if (flagDefinition.has(MPConstants.Flags.IS_QA_TESTER) && !flagDefinition.isNull(MPConstants.Flags.IS_QA_TESTER)) {
+                        isQATester = flagDefinition.getBoolean(MPConstants.Flags.IS_QA_TESTER);
+                    }
+
+                    MixpanelFlagVariant flagData = new MixpanelFlagVariant(variantKey, variantValue, experimentID, isExperimentActive, isQATester);
                     flagsMap.put(featureName, flagData);
 
                 } catch (JSONException e) {

src/main/java/com/mixpanel/android/util/MPConstants.java

@@ -21,5 +21,8 @@ public static class Flags {
         public static final String FLAGS_KEY = "flags";
         public static final String VARIANT_KEY = "variant_key";
         public static final String VARIANT_VALUE = "variant_value";
+        public static final String EXPERIMENT_ID = "experiment_id";
+        public static final String IS_EXPERIMENT_ACTIVE = "is_experiment_active";
+        public static final String IS_QA_TESTER = "is_qa_tester";
     }
 }