fix (forced variations): Move forced variation methods and state out of project config and into decision service (#24)

Summary:

This is a solution for persisting forced variation state when the project config is updated from datafile management. Just as in Java, we moved the forced variation map and forced variation methods into decision service.

Test plan:

- Existing unit tests are passing with no substantial changes: the changes I made in existing unit tests only update log message assertions to reflect the new location of forced variation methods (previously in project config, now in decision service).

- I moved forced variation method tests to the decision service tests file, and updated the method signatures to remove the logger argument (decision service already has a reference to its own logger).

- I added a few more unit tests covering cases where a previously set variation or experiment no longer exists on a new project config object.

Author: mjc1283

packages/optimizely-sdk/lib/core/decision_service/index.js

@@ -19,6 +19,7 @@ var bucketer = require('../bucketer');
 var enums = require('../../utils/enums');
 var fns = require('../../utils/fns');
 var projectConfig = require('../project_config');
+var stringValidator = require('../../utils/string_value_validator');
 
 var sprintf = require('@optimizely/js-sdk-utils').sprintf;
 
@@ -50,6 +51,7 @@ var DECISION_SOURCES = enums.DECISION_SOURCES;
 function DecisionService(options) {
   this.userProfileService = options.userProfileService || null;
   this.logger = options.logger;
+  this.forcedVariationMap = {};
 }
 
 /**
@@ -68,7 +70,7 @@ DecisionService.prototype.getVariation = function(configObj, experimentKey, user
     return null;
   }
   var experiment = configObj.experimentKeyMap[experimentKey];
-  var forcedVariationKey = projectConfig.getForcedVariation(configObj, experimentKey, userId, this.logger);
+  var forcedVariationKey = this.getForcedVariation(configObj, experimentKey, userId);
   if (!!forcedVariationKey) {
     return forcedVariationKey;
   }
@@ -468,6 +470,146 @@ DecisionService.prototype._getBucketingId = function(userId, attributes) {
   return bucketingId;
 };
 
+/**
+ * Removes forced variation for given userId and experimentKey
+ * @param  {string} userId         String representing the user id
+ * @param  {number} experimentId   Number representing the experiment id
+ * @param  {string} experimentKey  Key representing the experiment id
+ * @throws If the user id is not valid or not in the forced variation map
+ */
+DecisionService.prototype.removeForcedVariation = function(userId, experimentId, experimentKey) {
+  if (!userId) {
+    throw new Error(sprintf(ERROR_MESSAGES.INVALID_USER_ID, MODULE_NAME));
+  }
+
+  if (this.forcedVariationMap.hasOwnProperty(userId)) {
+    delete this.forcedVariationMap[userId][experimentId];
+    this.logger.log(LOG_LEVEL.DEBUG, sprintf(LOG_MESSAGES.VARIATION_REMOVED_FOR_USER, MODULE_NAME, experimentKey, userId));
+  } else {
+    throw new Error(sprintf(ERROR_MESSAGES.USER_NOT_IN_FORCED_VARIATION, MODULE_NAME, userId));
+  }
+};
+
+/**
+ * Sets forced variation for given userId and experimentKey
+ * @param  {string} userId        String representing the user id
+ * @param  {number} experimentId  Number representing the experiment id
+ * @param  {number} variationId   Number representing the variation id
+ * @throws If the user id is not valid
+ */
+DecisionService.prototype.__setInForcedVariationMap = function(userId, experimentId, variationId) {
+  if (this.forcedVariationMap.hasOwnProperty(userId)) {
+    this.forcedVariationMap[userId][experimentId] = variationId;
+  } else {
+    this.forcedVariationMap[userId] = {};
+    this.forcedVariationMap[userId][experimentId] = variationId;
+  }
+
+  this.logger.log(LOG_LEVEL.DEBUG, sprintf(LOG_MESSAGES.USER_MAPPED_TO_FORCED_VARIATION, MODULE_NAME, variationId, experimentId, userId));
+};
+
+/**
+ * Gets the forced variation key for the given user and experiment.
+ * @param  {Object} configObj        Object representing project configuration
+ * @param  {string} experimentKey    Key for experiment.
+ * @param  {string} userId           The user Id.
+ * @return {string|null} Variation   The variation which the given user and experiment should be forced into.
+ */
+DecisionService.prototype.getForcedVariation = function(configObj, experimentKey, userId) {
+  var experimentToVariationMap = this.forcedVariationMap[userId];
+  if (!experimentToVariationMap) {
+    this.logger.log(LOG_LEVEL.DEBUG, sprintf(LOG_MESSAGES.USER_HAS_NO_FORCED_VARIATION, MODULE_NAME, userId));
+    return null;
+  }
+
+  var experimentId;
+  try {
+    var experiment = projectConfig.getExperimentFromKey(configObj, experimentKey);
+    if (experiment.hasOwnProperty('id')) {
+      experimentId = experiment['id'];
+    } else {
+      // catching improperly formatted experiments
+      this.logger.log(LOG_LEVEL.ERROR, sprintf(ERROR_MESSAGES.IMPROPERLY_FORMATTED_EXPERIMENT, MODULE_NAME, experimentKey));
+      return null;
+    }
+  } catch (ex) {
+    // catching experiment not in datafile
+    this.logger.log(LOG_LEVEL.ERROR, ex.message);
+    return null;
+  }
+
+  var variationId = experimentToVariationMap[experimentId];
+  if (!variationId) {
+    this.logger.log(LOG_LEVEL.DEBUG, sprintf(LOG_MESSAGES.USER_HAS_NO_FORCED_VARIATION_FOR_EXPERIMENT, MODULE_NAME, experimentKey, userId));
+    return null;
+  }
+
+  var variationKey = projectConfig.getVariationKeyFromId(configObj, variationId);
+  if (variationKey) {
+    this.logger.log(LOG_LEVEL.DEBUG, sprintf(LOG_MESSAGES.USER_HAS_FORCED_VARIATION, MODULE_NAME, variationKey, experimentKey, userId));
+  } else {
+    this.logger.log(LOG_LEVEL.DEBUG, sprintf(LOG_MESSAGES.USER_HAS_NO_FORCED_VARIATION_FOR_EXPERIMENT, MODULE_NAME, experimentKey, userId));
+  }
+
+  return variationKey;
+};
+
+/**
+ * Sets the forced variation for a user in a given experiment
+ * @param  {Object} configObj      Object representing project configuration
+ * @param  {string} experimentKey  Key for experiment.
+ * @param  {string} userId         The user Id.
+ * @param  {string} variationKey   Key for variation. If null, then clear the existing experiment-to-variation mapping
+ * @return {boolean}               A boolean value that indicates if the set completed successfully.
+ */
+DecisionService.prototype.setForcedVariation = function(configObj, experimentKey, userId, variationKey) {
+  if (variationKey != null && !stringValidator.validate(variationKey)) {
+    this.logger.log(LOG_LEVEL.ERROR, sprintf(ERROR_MESSAGES.INVALID_VARIATION_KEY, MODULE_NAME));
+    return false;
+  }
+
+  var experimentId;
+  try {
+    var experiment = projectConfig.getExperimentFromKey(configObj, experimentKey);
+    if (experiment.hasOwnProperty('id')) {
+      experimentId = experiment['id'];
+    } else {
+      // catching improperly formatted experiments
+      this.logger.log(LOG_LEVEL.ERROR, sprintf(ERROR_MESSAGES.IMPROPERLY_FORMATTED_EXPERIMENT, MODULE_NAME, experimentKey));
+      return false;
+    }
+  } catch (ex) {
+    // catching experiment not in datafile
+    this.logger.log(LOG_LEVEL.ERROR, ex.message);
+    return false;
+  }
+
+  if (variationKey == null) {
+    try {
+      this.removeForcedVariation(userId, experimentId, experimentKey, this.logger);
+      return true;
+    } catch (ex) {
+      this.logger.log(LOG_LEVEL.ERROR, ex.message);
+      return false;
+    }
+  }
+
+  var variationId = projectConfig.getVariationIdFromExperimentAndVariationKey(configObj, experimentKey, variationKey);
+
+  if (!variationId) {
+    this.logger.log(LOG_LEVEL.ERROR, sprintf(ERROR_MESSAGES.NO_VARIATION_FOR_EXPERIMENT_KEY, MODULE_NAME, variationKey, experimentKey));
+    return false;
+  }
+
+  try {
+    this.__setInForcedVariationMap(userId, experimentId, variationId);
+    return true;
+  } catch (ex) {
+    this.logger.log(LOG_LEVEL.ERROR, ex.message);
+    return false;
+  }
+};
+
 module.exports = {
   /**
    * Creates an instance of the DecisionService.