diff --git a/toolkit/components/normandy/actions/ShowHeartbeatAction.jsm b/toolkit/components/normandy/actions/ShowHeartbeatAction.jsm
new file mode 100644
index 000000000000..abb339323327
--- /dev/null
+++ b/toolkit/components/normandy/actions/ShowHeartbeatAction.jsm
@@ -0,0 +1,209 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+ChromeUtils.import("resource://normandy/actions/BaseAction.jsm");
+ChromeUtils.defineModuleGetter(this, "ActionSchemas", "resource://normandy/actions/schemas/index.js");
+ChromeUtils.defineModuleGetter(this, "BrowserWindowTracker", "resource://gre/modules/BrowserWindowTracker.jsm");
+ChromeUtils.defineModuleGetter(this, "ClientEnvironment", "resource://normandy/lib/ClientEnvironment.jsm");
+ChromeUtils.defineModuleGetter(this, "Heartbeat", "resource://normandy/lib/Heartbeat.jsm");
+ChromeUtils.defineModuleGetter(this, "ShellService", "resource:///modules/ShellService.jsm");
+ChromeUtils.defineModuleGetter(this, "Storage", "resource://normandy/lib/Storage.jsm");
+ChromeUtils.defineModuleGetter(this, "UpdateUtils", "resource://gre/modules/UpdateUtils.jsm");
+
+XPCOMUtils.defineLazyServiceGetter(this, "uuidGenerator", "@mozilla.org/uuid-generator;1", "nsIUUIDGenerator");
+
+var EXPORTED_SYMBOLS = ["ShowHeartbeatAction"];
+
+XPCOMUtils.defineLazyGetter(this, "gAllRecipeStorage", function() {
+  return new Storage("normandy-heartbeat");
+});
+
+const DAY_IN_MS = 24 * 60 * 60 * 1000;
+const HEARTBEAT_THROTTLE = 1 * DAY_IN_MS;
+
+class ShowHeartbeatAction extends BaseAction {
+  get schema() {
+    return ActionSchemas["show-heartbeat"];
+  }
+
+  async _run(recipe) {
+    const {
+      message,
+      engagementButtonLabel,
+      thanksMessage,
+      learnMoreMessage,
+      learnMoreUrl,
+    } = recipe.arguments;
+
+    const recipeStorage = new Storage(recipe.id);
+
+    if (!await this.shouldShow(recipeStorage, recipe)) {
+      return;
+    }
+
+    this.log.debug(`Heartbeat for recipe ${recipe.id} showing prompt "${message}"`);
+    const targetWindow = BrowserWindowTracker.getTopWindow();
+
+    if (!targetWindow) {
+      throw new Error("No window to show heartbeat in");
+    }
+
+    const heartbeat = new Heartbeat(targetWindow, {
+      surveyId: this.generateSurveyId(recipe),
+      message,
+      engagementButtonLabel,
+      thanksMessage,
+      learnMoreMessage,
+      learnMoreUrl,
+      postAnswerUrl: await this.generatePostAnswerURL(recipe),
+      flowId: this.uuid(),
+      surveyVersion: recipe.revision_id,
+    });
+
+    heartbeat.eventEmitter.once("Voted", this.updateLastInteraction.bind(this, recipeStorage));
+    heartbeat.eventEmitter.once("Engaged", this.updateLastInteraction.bind(this, recipeStorage));
+
+    let now = Date.now();
+    await Promise.all([
+      gAllRecipeStorage.setItem("lastShown", now),
+      recipeStorage.setItem("lastShown", now),
+    ]);
+  }
+
+  async shouldShow(recipeStorage, recipe) {
+    const { repeatOption, repeatEvery } = recipe.arguments;
+    // Don't show any heartbeats to a user more than once per throttle period
+    let lastShown = await gAllRecipeStorage.getItem("lastShown");
+    if (lastShown) {
+      const duration = new Date() - lastShown;
+      if (duration < HEARTBEAT_THROTTLE) {
+        // show the number of hours since the last heartbeat, with at most 1 decimal point.
+        const hoursAgo = Math.floor(duration / 1000 / 60 / 6) / 10;
+        this.log.debug(`A heartbeat was shown too recently (${hoursAgo} hours), skipping recipe ${recipe.id}.`);
+        return false;
+      }
+    }
+
+    switch (repeatOption) {
+      case "once": {
+        // Don't show if we've ever shown before
+        if (await recipeStorage.getItem("lastShown")) {
+          this.log.debug(`Heartbeat for "once" recipe ${recipe.id} has been shown before, skipping.`);
+          return false;
+        }
+      }
+
+      case "nag": {
+        // Show a heartbeat again only if the user has not interacted with it before
+        if (await recipeStorage.getItem("lastInteraction")) {
+          this.log.debug(`Heartbeat for "nag" recipe ${recipe.id} has already been interacted with, skipping.`);
+          return false;
+        }
+      }
+
+      case "xdays": {
+        // Show this heartbeat again if it  has been at least `repeatEvery` days since the last time it was shown.
+        let lastShown = await gAllRecipeStorage.getItem("lastShown");
+        if (lastShown) {
+          lastShown = new Date(lastShown);
+          const duration  = new Date() - lastShown;
+          if (duration < repeatEvery * DAY_IN_MS) {
+            // show the number of hours since the last time this hearbeat was shown, with at most 1 decimal point.
+            const hoursAgo = Math.floor(duration / 1000 / 60 / 6) / 10;
+            this.log.debug(
+              `Heartbeat for "xdays" recipe ${recipe.id} ran in the last ${repeatEvery} days, skipping. (${hoursAgo} hours ago)`
+            );
+            return false;
+          }
+        }
+      }
+    }
+
+    return true;
+  }
+
+  /**
+   * Returns a surveyId value. If recipe calls to include the Normandy client
+   * ID, then the client ID is attached to the surveyId in the format
+   * `${surveyId}::${userId}`.
+   *
+   * @return {String} Survey ID, possibly with user UUID
+   */
+  generateSurveyId(recipe) {
+    const { includeTelemetryUUID, surveyId } = recipe.arguments;
+    if (includeTelemetryUUID) {
+      return `${surveyId}::${ClientEnvironment.userId}`;
+    }
+    return surveyId;
+  }
+
+  /*
+   * Generate a UUID without surrounding brackets, as expected by Heartbeat
+   * telemetry.
+   */
+  uuid() {
+    let rv = uuidGenerator.generateUUID().toString();
+    return rv.slice(1, rv.length - 1);
+  }
+
+  /**
+   * Generate the appropriate post-answer URL for a recipe.
+   * @param  recipe
+   * @return {String} URL with post-answer query params
+   */
+  async generatePostAnswerURL(recipe) {
+    const { postAnswerUrl, message, includeTelemetryUUID } = recipe.arguments;
+
+    // Don`t bother with empty URLs.
+    if (!postAnswerUrl) {
+      return postAnswerUrl;
+    }
+
+    const userId = ClientEnvironment.userId;
+    const searchEngine = await new Promise(resolve => {
+      Services.search.init(rv => {
+        if (Components.isSuccessCode(rv)) {
+          resolve(Services.search.defaultEngine.identifier);
+        }
+      });
+    });
+
+    const args = {
+      fxVersion: Services.appinfo.version,
+      isDefaultBrowser: ShellService.isDefaultBrowser() ? 1 : 0,
+      searchEngine,
+      source: "heartbeat",
+      // `surveyversion` used to be the version of the heartbeat action when it
+      // was hosted on a server. Keeping it around for compatibility.
+      surveyversion: Services.appinfo.version,
+      syncSetup: Services.prefs.prefHasUserValue("services.sync.username") ? 1 : 0,
+      updateChannel: UpdateUtils.getUpdateChannel(false),
+      utm_campaign: encodeURIComponent(message.replace(/\s+/g, "")),
+      utm_medium: recipe.action,
+      utm_source: "firefox",
+    };
+    if (includeTelemetryUUID) {
+      args.userId = userId;
+    }
+
+    let url = new URL(postAnswerUrl);
+    // create a URL object to append arguments to
+    for (const [key, val] of Object.entries(args)) {
+      if (!url.searchParams.has(key)) {
+        url.searchParams.set(key, val);
+      }
+    }
+
+    // return the address with encoded queries
+    return url.toString();
+  }
+
+  updateLastInteraction(recipeStorage) {
+    recipeStorage.setItem("lastInteraction", Date.now());
+  }
+}
diff --git a/toolkit/components/normandy/actions/schemas/index.js b/toolkit/components/normandy/actions/schemas/index.js
index 70b381d56b7a..8febbdf7b7f8 100644
--- a/toolkit/components/normandy/actions/schemas/index.js
+++ b/toolkit/components/normandy/actions/schemas/index.js
@@ -95,6 +95,87 @@ const ActionSchemas = {
       },
     },
   },
+
+  "show-heartbeat": {
+    "$schema": "http://json-schema.org/draft-04/schema#",
+    "title": "Show a Heartbeat survey.",
+    "description": "This action shows a single survey.",
+
+    "type": "object",
+    "required": [
+      "surveyId",
+      "message",
+      "thanksMessage",
+      "postAnswerUrl",
+      "learnMoreMessage",
+      "learnMoreUrl",
+    ],
+    "properties": {
+      "repeatOption": {
+        "type": "string",
+        "enum": ["once", "xdays", "nag"],
+        "description": "Determines how often a prompt is shown executes.",
+        "default": "once",
+      },
+      "repeatEvery": {
+        "description": "For repeatOption=xdays, how often (in days) the prompt is displayed.",
+        "default": null,
+        "anyOf": [
+          { "type": "number", "minimum": 1 },
+          { "type": "null" },
+        ],
+      },
+      "includeTelemetryUUID": {
+        "type": "boolean",
+        "description": "Include unique user ID in post-answer-url and Telemetry",
+        "default": false,
+      },
+      "surveyId": {
+        "type": "string",
+        "description": "Slug uniquely identifying this survey in telemetry",
+      },
+      "message": {
+        "description": "Message to show to the user",
+        "type": "string",
+      },
+      "engagementButtonLabel": {
+        "description": "Text for the engagement button. If specified, this button will be shown instead of rating stars.",
+        "default": null,
+        "anyOf": [
+          { "type": "string" },
+          { "type": "null" },
+        ],
+      },
+      "thanksMessage": {
+        "description": "Thanks message to show to the user after they've rated Firefox",
+        "type": "string",
+      },
+      "postAnswerUrl": {
+        "description": "URL to redirect the user to after rating Firefox or clicking the engagement button",
+        "default": null,
+        "anyOf": [
+          { "type": "string" },
+          { "type": "null" },
+        ],
+      },
+      "learnMoreMessage": {
+        "description": "Message to show to the user to learn more",
+        "default": null,
+        "anyOf": [
+          { "type": "string" },
+          { "type": "null" },
+        ],
+      },
+      "learnMoreUrl": {
+        "description": "URL to show to the user when they click Learn More",
+        "default": null,
+        "anyOf": [
+          { "type": "string" },
+          { "type": "null" },
+        ],
+      },
+    },
+  },
 };
 
 // Legacy name used on Normandy server
diff --git a/toolkit/components/normandy/actions/schemas/package.json b/toolkit/components/normandy/actions/schemas/package.json
index 4b669f84aeb3..b07a62f4e794 100644
--- a/toolkit/components/normandy/actions/schemas/package.json
+++ b/toolkit/components/normandy/actions/schemas/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@mozilla/normandy-action-argument-schemas",
-  "version": "0.5.0",
+  "version": "0.6.0",
   "description": "Schemas for Normandy action arguments",
   "main": "index.js",
   "author": "Michael Cooper <mcooper@mozilla.com>",
diff --git a/toolkit/components/normandy/lib/ActionsManager.jsm b/toolkit/components/normandy/lib/ActionsManager.jsm
index f27490ca8ac1..c941ae8d4bdd 100644
--- a/toolkit/components/normandy/lib/ActionsManager.jsm
+++ b/toolkit/components/normandy/lib/ActionsManager.jsm
@@ -3,12 +3,13 @@ ChromeUtils.import("resource://normandy/lib/LogManager.jsm");
 
 XPCOMUtils.defineLazyModuleGetters(this, {
   ActionSandboxManager: "resource://normandy/lib/ActionSandboxManager.jsm",
-  NormandyApi: "resource://normandy/lib/NormandyApi.jsm",
-  Uptake: "resource://normandy/lib/Uptake.jsm",
   AddonStudyAction: "resource://normandy/actions/AddonStudyAction.jsm",
   ConsoleLogAction: "resource://normandy/actions/ConsoleLogAction.jsm",
-  PreferenceRolloutAction: "resource://normandy/actions/PreferenceRolloutAction.jsm",
+  NormandyApi: "resource://normandy/lib/NormandyApi.jsm",
   PreferenceRollbackAction: "resource://normandy/actions/PreferenceRollbackAction.jsm",
+  PreferenceRolloutAction: "resource://normandy/actions/PreferenceRolloutAction.jsm",
+  ShowHeartbeatAction: "resource://normandy/actions/ShowHeartbeatAction.jsm",
+  Uptake: "resource://normandy/lib/Uptake.jsm",
 });
 
 var EXPORTED_SYMBOLS = ["ActionsManager"];
@@ -34,9 +35,10 @@ class ActionsManager {
     this.localActions = {
       "addon-study": addonStudyAction,
       "console-log": new ConsoleLogAction(),
-      "preference-rollout": new PreferenceRolloutAction(),
+      "opt-out-study": addonStudyAction, // Legacy name used for addon-study on Normandy server
       "preference-rollback": new PreferenceRollbackAction(),
-      "opt-out-study": addonStudyAction, // Legacy name used on Normandy server
+      "preference-rollout": new PreferenceRolloutAction(),
+      "show-heartbeat": new ShowHeartbeatAction(),
     };
   }
 
diff --git a/toolkit/components/normandy/lib/EventEmitter.jsm b/toolkit/components/normandy/lib/EventEmitter.jsm
index 88cb06c588ab..c984b6224c30 100644
--- a/toolkit/components/normandy/lib/EventEmitter.jsm
+++ b/toolkit/components/normandy/lib/EventEmitter.jsm
@@ -9,18 +9,10 @@ var EXPORTED_SYMBOLS = ["EventEmitter"];
 
 const log = LogManager.getLogger("event-emitter");
 
-var EventEmitter = function(sandboxManager) {
+var EventEmitter = function() {
   const listeners = {};
 
   return {
-    createSandboxedEmitter() {
-      return sandboxManager.cloneInto({
-        on: this.on.bind(this),
-        off: this.off.bind(this),
-        once: this.once.bind(this),
-      }, {cloneFunctions: true});
-    },
-
     emit(eventName, event) {
       // Fire events async
       Promise.resolve()
@@ -32,7 +24,7 @@ var EventEmitter = function(sandboxManager) {
           // Clone callbacks array to avoid problems with mutation while iterating
           const callbacks = Array.from(listeners[eventName]);
           for (const cb of callbacks) {
-            cb(sandboxManager.cloneInto(event));
+            cb(event);
           }
         });
     },
diff --git a/toolkit/components/normandy/lib/Heartbeat.jsm b/toolkit/components/normandy/lib/Heartbeat.jsm
index c0b418a85785..eb27922beb56 100644
--- a/toolkit/components/normandy/lib/Heartbeat.jsm
+++ b/toolkit/components/normandy/lib/Heartbeat.jsm
@@ -48,9 +48,6 @@ CleanupManager.addCleanupHandler(() => {
  *
  * @param chromeWindow
  *        The chrome window that the heartbeat notification is displayed in.
- * @param sandboxManager
- *        The manager for the sandbox this was called from. Heartbeat will
- *        increment the hold counter on the manager.
  * @param {Object} options Options object.
  * @param {String} options.message
  *        The message, or question, to display on the notification.
@@ -60,7 +57,7 @@ CleanupManager.addCleanupHandler(() => {
  *        An identifier for this rating flow. Please note that this is only used to
  *        identify the notification box.
  * @param {String} [options.engagementButtonLabel=null]
- *        The text of the engagement button to use instad of stars. If this is null
+ *        The text of the engagement button to use instead of stars. If this is null
  *        or invalid, rating stars are used.
  * @param {String} [options.learnMoreMessage=null]
  *        The label of the learn more link. No link will be shown if this is null.
@@ -77,7 +74,7 @@ CleanupManager.addCleanupHandler(() => {
  *        The url to visit after the user answers the question.
  */
 var Heartbeat = class {
-  constructor(chromeWindow, sandboxManager, options) {
+  constructor(chromeWindow, options) {
     if (typeof options.flowId !== "string") {
       throw new Error("flowId must be a string");
     }
@@ -94,10 +91,6 @@ var Heartbeat = class {
       throw new Error("message must not be an empty string");
     }
 
-    if (!sandboxManager) {
-      throw new Error("sandboxManager must be provided");
-    }
-
     if (options.postAnswerUrl) {
       options.postAnswerUrl = new URL(options.postAnswerUrl);
     } else {
@@ -113,8 +106,7 @@ var Heartbeat = class {
     }
 
     this.chromeWindow = chromeWindow;
-    this.eventEmitter = new EventEmitter(sandboxManager);
-    this.sandboxManager = sandboxManager;
+    this.eventEmitter = new EventEmitter();
     this.options = options;
     this.surveyResults = {};
     this.buttons = null;
@@ -237,13 +229,12 @@ var Heartbeat = class {
       this.close();
     }, surveyDuration);
 
-    this.sandboxManager.addHold("heartbeat");
     CleanupManager.addCleanupHandler(this.close);
   }
 
   maybeNotifyHeartbeat(name, data = {}) {
     if (this.pingSent) {
-      log.warn("Heartbeat event recieved after Telemetry ping sent. name:", name, "data:", data);
+      log.warn("Heartbeat event received after Telemetry ping sent. name:", name, "data:", data);
       return;
     }
 
@@ -374,8 +365,6 @@ var Heartbeat = class {
     // Kill the timers which might call things after we've cleaned up:
     this.endTimerIfPresent("surveyEndTimer");
     this.endTimerIfPresent("engagementCloseTimer");
-
-    this.sandboxManager.removeHold("heartbeat");
     // remove listeners
     this.chromeWindow.removeEventListener("SSWindowClosing", this.handleWindowClosed);
     // remove references for garbage collection
@@ -386,7 +375,6 @@ var Heartbeat = class {
     this.rightSpacer = null;
     this.learnMore = null;
     this.eventEmitter = null;
-    this.sandboxManager = null;
     // Ensure we don't re-enter and release the CleanupManager's reference to us:
     CleanupManager.removeCleanupHandler(this.close);
   }
diff --git a/toolkit/components/normandy/lib/NormandyDriver.jsm b/toolkit/components/normandy/lib/NormandyDriver.jsm
index 2755f439288f..2ebb10f98c4c 100644
--- a/toolkit/components/normandy/lib/NormandyDriver.jsm
+++ b/toolkit/components/normandy/lib/NormandyDriver.jsm
@@ -11,7 +11,6 @@ ChromeUtils.import("resource://gre/modules/AddonManager.jsm");
 ChromeUtils.import("resource://gre/modules/Timer.jsm");
 ChromeUtils.import("resource://normandy/lib/LogManager.jsm");
 ChromeUtils.import("resource://normandy/lib/Storage.jsm");
-ChromeUtils.import("resource://normandy/lib/Heartbeat.jsm");
 ChromeUtils.import("resource://normandy/lib/ClientEnvironment.jsm");
 ChromeUtils.import("resource://normandy/lib/PreferenceExperiments.jsm");
 
@@ -23,7 +22,6 @@ const {generateUUID} = Cc["@mozilla.org/uuid-generator;1"].getService(Ci.nsIUUID
 
 var EXPORTED_SYMBOLS = ["NormandyDriver"];
 
-const log = LogManager.getLogger("normandy-driver");
 const actionLog = LogManager.getLogger("normandy-driver.actions");
 
 var NormandyDriver = function(sandboxManager) {
@@ -57,23 +55,6 @@ var NormandyDriver = function(sandboxManager) {
       actionLog[level](message);
     },
 
-    showHeartbeat(options) {
-      log.info(`Showing heartbeat prompt "${options.message}"`);
-      const aWindow = Services.wm.getMostRecentWindow("navigator:browser");
-
-      if (!aWindow) {
-        return sandbox.Promise.reject(new sandbox.Error("No window to show heartbeat in"));
-      }
-
-      const internalOptions = Object.assign({}, options, {testing: this.testing});
-      const heartbeat = new Heartbeat(aWindow, sandboxManager, internalOptions);
-      return sandbox.Promise.resolve(heartbeat.eventEmitter.createSandboxedEmitter());
-    },
-
-    saveHeartbeatFlow() {
-      // no-op required by spec
-    },
-
     client() {
       const appinfo = {
         version: Services.appinfo.version,
diff --git a/toolkit/components/normandy/lib/Storage.jsm b/toolkit/components/normandy/lib/Storage.jsm
index 1d61f1355c67..3fc1974c0f80 100644
--- a/toolkit/components/normandy/lib/Storage.jsm
+++ b/toolkit/components/normandy/lib/Storage.jsm
@@ -48,7 +48,7 @@ var Storage = class {
   /**
    * Sets an item in the prefixed storage.
    * @returns {Promise}
-   * @resolves When the operation is completed succesfully
+   * @resolves When the operation is completed successfully
    * @rejects Javascript exception.
    */
   async setItem(name, value) {
@@ -63,7 +63,7 @@ var Storage = class {
   /**
    * Removes a single item from the prefixed storage.
    * @returns {Promise}
-   * @resolves When the operation is completed succesfully
+   * @resolves When the operation is completed successfully
    * @rejects Javascript exception.
    */
   async removeItem(name) {
@@ -77,7 +77,7 @@ var Storage = class {
   /**
    * Clears all storage for the prefix.
    * @returns {Promise}
-   * @resolves When the operation is completed succesfully
+   * @resolves When the operation is completed successfully
    * @rejects Javascript exception.
    */
   async clear() {
diff --git a/toolkit/components/normandy/test/browser/browser.ini b/toolkit/components/normandy/test/browser/browser.ini
index 173d31ddd412..4a47111de79f 100644
--- a/toolkit/components/normandy/test/browser/browser.ini
+++ b/toolkit/components/normandy/test/browser/browser.ini
@@ -11,6 +11,7 @@ skip-if = !healthreport || !telemetry
 [browser_actions_ConsoleLogAction.js]
 [browser_actions_PreferenceRolloutAction.js]
 [browser_actions_PreferenceRollbackAction.js]
+[browser_actions_ShowHeartbeatAction.js]
 [browser_ActionSandboxManager.js]
 [browser_ActionsManager.js]
 [browser_AddonStudies.js]
diff --git a/toolkit/components/normandy/test/browser/browser_actions_ShowHeartbeatAction.js b/toolkit/components/normandy/test/browser/browser_actions_ShowHeartbeatAction.js
new file mode 100644
index 000000000000..6157a8da293b
--- /dev/null
+++ b/toolkit/components/normandy/test/browser/browser_actions_ShowHeartbeatAction.js
@@ -0,0 +1,298 @@
+"use strict";
+
+ChromeUtils.import("resource://normandy/actions/ShowHeartbeatAction.jsm", this);
+ChromeUtils.import("resource://normandy/lib/ClientEnvironment.jsm", this);
+ChromeUtils.import("resource://normandy/lib/Heartbeat.jsm", this);
+ChromeUtils.import("resource://normandy/lib/Storage.jsm", this);
+ChromeUtils.import("resource://normandy/lib/Uptake.jsm", this);
+
+const HOUR_IN_MS = 60 * 60 * 1000;
+
+function heartbeatRecipeFactory(overrides = {}) {
+  const defaults = {
+    revision_id: 1,
+    name: "Test Recipe",
+    action: "show-heartbeat",
+    arguments: {
+      surveyId: "a survey",
+      message: "test message",
+      engagementButtonLabel: "",
+      thanksMessage: "thanks!",
+      postAnswerUrl: "http://example.com",
+      learnMoreMessage: "Learn More",
+      learnMoreUrl: "http://example.com",
+      repeatOption: "once",
+    },
+  };
+
+  if (overrides.arguments) {
+    defaults.arguments = Object.assign(defaults.arguments, overrides.arguments);
+    delete overrides.arguments;
+  }
+
+  return recipeFactory(Object.assign(defaults, overrides));
+}
+
+class MockHeartbeat {
+  constructor() {
+    this.eventEmitter = new MockEventEmitter();
+  }
+}
+
+class MockEventEmitter {
+  constructor() {
+    this.once = sinon.stub();
+  }
+}
+
+function withStubbedHeartbeat(testFunction) {
+  return async function wrappedTestFunction(...args) {
+    const backstage = ChromeUtils.import("resource://normandy/actions/ShowHeartbeatAction.jsm", {});
+    const originalHeartbeat = backstage.Heartbeat;
+    const heartbeatInstanceStub = new MockHeartbeat();
+    const heartbeatClassStub = sinon.stub();
+    heartbeatClassStub.returns(heartbeatInstanceStub);
+    backstage.Heartbeat = heartbeatClassStub;
+
+    try {
+      await testFunction({heartbeatClassStub, heartbeatInstanceStub}, ...args);
+    } finally {
+      backstage.Heartbeat = originalHeartbeat;
+    }
+  };
+}
+
+function withClearStorage(testFunction) {
+  return async function wrappedTestFunction(...args) {
+    Storage.clearAllStorage();
+    try {
+      await testFunction(...args);
+    } finally {
+      Storage.clearAllStorage();
+    }
+  };
+}
+
+// Test that a normal heartbeat works as expected
+decorate_task(
+  withStubbedHeartbeat,
+  withClearStorage,
+  async function testHappyPath({ heartbeatClassStub, heartbeatInstanceStub }) {
+    const recipe = heartbeatRecipeFactory();
+    const action = new ShowHeartbeatAction();
+    await action.runRecipe(recipe);
+    await action.finalize();
+    is(action.state, ShowHeartbeatAction.STATE_FINALIZED, "Action should be finalized");
+    is(action.lastError, null, "No errors should have been thrown");
+
+    const options = heartbeatClassStub.args[0][1];
+    Assert.deepEqual(
+      heartbeatClassStub.args,
+      [[
+        heartbeatClassStub.args[0][0], // target window
+        {
+          surveyId: options.surveyId,
+          message: recipe.arguments.message,
+          engagementButtonLabel: recipe.arguments.engagementButtonLabel,
+          thanksMessage: recipe.arguments.thanksMessage,
+          learnMoreMessage: recipe.arguments.learnMoreMessage,
+          learnMoreUrl: recipe.arguments.learnMoreUrl,
+          postAnswerUrl: options.postAnswerUrl,
+          flowId: options.flowId,
+          surveyVersion: recipe.revision_id,
+        },
+      ]],
+      "expected arguments were passed",
+    );
+
+    const uuidRegex = /[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}/i;
+    ok(options.flowId.match(uuidRegex), "flowId should be a uuid");
+
+    // postAnswerUrl gains several query string parameters. Check that the prefix is right
+    ok(options.postAnswerUrl.startsWith(recipe.arguments.postAnswerUrl));
+
+    ok(heartbeatInstanceStub.eventEmitter.once.calledWith("Voted"), "Voted event handler should be registered");
+    ok(heartbeatInstanceStub.eventEmitter.once.calledWith("Engaged"), "Engaged event handler should be registered");
+  }
+);
+
+/* Test that heartbeat doesn't show if an unrelated heartbeat has shown recently. */
+decorate_task(
+  withStubbedHeartbeat,
+  withClearStorage,
+  async function testRepeatGeneral({ heartbeatClassStub }) {
+    const allHeartbeatStorage = new Storage("normandy-heartbeat");
+    await allHeartbeatStorage.setItem("lastShown", Date.now());
+    const recipe = heartbeatRecipeFactory();
+
+    const action = new ShowHeartbeatAction();
+    await action.runRecipe(recipe);
+    is(action.lastError, null, "No errors should have been thrown");
+
+    is(heartbeatClassStub.args.length, 0, "Heartbeat should not be called once");
+  },
+);
+
+/* Test that a heartbeat shows if an unrelated heartbeat showed more than 24 hours ago. */
+decorate_task(
+  withStubbedHeartbeat,
+  withClearStorage,
+  async function testRepeatUnrelated({ heartbeatClassStub }) {
+    const allHeartbeatStorage = new Storage("normandy-heartbeat");
+    await allHeartbeatStorage.setItem("lastShown", Date.now() - 25 * HOUR_IN_MS);
+    const recipe = heartbeatRecipeFactory();
+
+    const action = new ShowHeartbeatAction();
+    await action.runRecipe(recipe);
+    is(action.lastError, null, "No errors should have been thrown");
+
+    is(heartbeatClassStub.args.length, 1, "Heartbeat should be called once");
+  },
+);
+
+/* Test that a repeat=once recipe is not shown again, even more than 24 hours ago. */
+decorate_task(
+  withStubbedHeartbeat,
+  withClearStorage,
+  async function testRepeatTypeOnce({ heartbeatClassStub }) {
+    const recipe = heartbeatRecipeFactory({ arguments: { repeatOption: "once" }});
+    const recipeStorage = new Storage(recipe.id);
+    await recipeStorage.setItem("lastShown", Date.now() - 25 * HOUR_IN_MS);
+
+    const action = new ShowHeartbeatAction();
+    await action.runRecipe(recipe);
+    is(action.lastError, null, "No errors should have been thrown");
+
+    is(heartbeatClassStub.args.length, 0, "Heartbeat should not be called");
+  },
+);
+
+/* Test that a repeat=xdays recipe is shown again, only after the expected number of days. */
+decorate_task(
+  withStubbedHeartbeat,
+  withClearStorage,
+  async function testRepeatTypeXdays({ heartbeatClassStub }) {
+    const recipe = heartbeatRecipeFactory({ arguments: {
+      repeatOption: "xdays",
+      repeatEvery: 2,
+    }});
+    const recipeStorage = new Storage(recipe.id);
+    const allHeartbeatStorage = new Storage("normandy-heartbeat");
+
+    await recipeStorage.setItem("lastShown", Date.now() - 25 * HOUR_IN_MS);
+    await allHeartbeatStorage.setItem("lastShown", Date.now() - 25 * HOUR_IN_MS);
+    const action = new ShowHeartbeatAction();
+    await action.runRecipe(recipe);
+    is(action.lastError, null, "No errors should have been thrown");
+    is(heartbeatClassStub.args.length, 0, "Heartbeat should not be called");
+
+    await recipeStorage.setItem("lastShown", Date.now() - 50 * HOUR_IN_MS);
+    await allHeartbeatStorage.setItem("lastShown", Date.now() - 50 * HOUR_IN_MS);
+    await action.runRecipe(recipe);
+    is(action.lastError, null, "No errors should have been thrown");
+    is(heartbeatClassStub.args.length, 1, "Heartbeat should have been called once");
+  },
+);
+
+/* Test that a repeat=nag recipe is shown again until lastInteraction is set */
+decorate_task(
+  withStubbedHeartbeat,
+  withClearStorage,
+  async function testRepeatTypeNag({ heartbeatClassStub }) {
+    const recipe = heartbeatRecipeFactory({ arguments: { repeatOption: "nag" }});
+    const recipeStorage = new Storage(recipe.id);
+    const allHeartbeatStorage = new Storage("normandy-heartbeat");
+
+    await allHeartbeatStorage.setItem("lastShown", Date.now() - 25 * HOUR_IN_MS);
+    await recipeStorage.setItem("lastShown", Date.now() - 25 * HOUR_IN_MS);
+    const action = new ShowHeartbeatAction();
+    await action.runRecipe(recipe);
+    is(action.lastError, null, "No errors should have been thrown");
+    is(heartbeatClassStub.args.length, 1, "Heartbeat should be called");
+
+    await allHeartbeatStorage.setItem("lastShown", Date.now() - 50 * HOUR_IN_MS);
+    await recipeStorage.setItem("lastShown", Date.now() - 50 * HOUR_IN_MS);
+    await action.runRecipe(recipe);
+    is(action.lastError, null, "No errors should have been thrown");
+    is(heartbeatClassStub.args.length, 2, "Heartbeat should be called again");
+
+    await allHeartbeatStorage.setItem("lastShown", Date.now() - 75 * HOUR_IN_MS);
+    await recipeStorage.setItem("lastShown", Date.now() - 75 * HOUR_IN_MS);
+    await recipeStorage.setItem("lastInteraction", Date.now() - 50 * HOUR_IN_MS);
+    await action.runRecipe(recipe);
+    is(action.lastError, null, "No errors should have been thrown");
+    is(heartbeatClassStub.args.length, 2, "Heartbeat should not be called again");
+  },
+);
+
+/* generatePostAnswerURL shouldn't annotate empty strings */
+add_task(
+  async function postAnswerEmptyString() {
+    const recipe = heartbeatRecipeFactory({ arguments: { postAnswerUrl: "" }});
+    const action = new ShowHeartbeatAction();
+    is(await action.generatePostAnswerURL(recipe), "", "an empty string should not be annotated");
+  }
+);
+
+/* generatePostAnswerURL should include the right details */
+add_task(
+  async function postAnswerUrl() {
+    const recipe = heartbeatRecipeFactory({ arguments: {
+      postAnswerUrl: "https://example.com/survey?survey_id=42",
+      includeTelemetryUUID: false,
+      message: "Hello, World!",
+    }});
+    const action = new ShowHeartbeatAction();
+    const url = new URL(await action.generatePostAnswerURL(recipe));
+
+    is(url.searchParams.get("survey_id"), "42", "Pre-existing search parameters should be preserved");
+    is(url.searchParams.get("fxVersion"), Services.appinfo.version, "Firefox version should be included");
+    is(url.searchParams.get("surveyversion"), Services.appinfo.version, "Survey version should also be the Firefox version");
+    ok(["0", "1"].includes(url.searchParams.get("syncSetup")), `syncSetup should be 0 or 1, got ${url.searchParams.get("syncSetup")}`);
+    is(url.searchParams.get("updateChannel"), UpdateUtils.getUpdateChannel("false"), "Update channel should be included");
+    ok(!url.searchParams.has("userId"), "no user id should be included");
+    is(url.searchParams.get("utm_campaign"), "Hello%2CWorld!", "utm_campaign should be an encoded version of the message");
+    is(url.searchParams.get("utm_medium"), "show-heartbeat", "utm_medium should be the action name");
+    is(url.searchParams.get("utm_source"), "firefox", "utm_source should be firefox");
+  }
+);
+
+/* generatePostAnswerURL shouldn't override existing values in the url */
+add_task(
+  async function postAnswerUrlNoOverwite() {
+    const recipe = heartbeatRecipeFactory({ arguments: {
+      postAnswerUrl: "https://example.com/survey?utm_source=shady_tims_firey_fox",
+    }});
+    const action = new ShowHeartbeatAction();
+    const url = new URL(await action.generatePostAnswerURL(recipe));
+    is(url.searchParams.get("utm_source"), "shady_tims_firey_fox", "utm_source should not be overwritten");
+  }
+);
+
+/* generatePostAnswerURL should only include userId if requested */
+add_task(
+  async function postAnswerUrlUserIdIfRequested() {
+    const recipeWithId = heartbeatRecipeFactory({ arguments: { includeTelemetryUUID: true }});
+    const recipeWithoutId = heartbeatRecipeFactory({ arguments: { includeTelemetryUUID: false }});
+    const action = new ShowHeartbeatAction();
+
+    const urlWithId = new URL(await action.generatePostAnswerURL(recipeWithId));
+    is(urlWithId.searchParams.get("userId"), ClientEnvironment.userId, "clientId should be included");
+
+    const urlWithoutId = new URL(await action.generatePostAnswerURL(recipeWithoutId));
+    ok(!urlWithoutId.searchParams.has("userId"), "userId should not be included");
+  }
+);
+
+/* generateSurveyId should include userId only if requested */
+decorate_task(
+  withStubbedHeartbeat,
+  withClearStorage,
+  async function testGenerateSurveyId({ heartbeatClassStub }) {
+    const recipeWithoutId = heartbeatRecipeFactory({ arguments: { surveyId: "test-id", includeTelemetryUUID: false }});
+    const recipeWithId = heartbeatRecipeFactory({ arguments: { surveyId: "test-id", includeTelemetryUUID: true }});
+    const action = new ShowHeartbeatAction();
+    is(action.generateSurveyId(recipeWithoutId), "test-id", "userId should not be included if not requested");
+    is(action.generateSurveyId(recipeWithId), `test-id::${ClientEnvironment.userId}`, "userId should be included if requested");
+  }
+);