[js] Reduce the API on promise.Thenable for compatibility with native Promises.

#2969

Author: jleyba

javascript/node/selenium-webdriver/CHANGES.md

@@ -16,6 +16,10 @@
 ### API Changes
 
  * Removed `safari.Options#useLegacyDriver()`
+ * Reduced the API on `promise.Thenable` for compatibility with native promises:
+   - Removed `#isPending()`
+   - Removed `#cancel()`
+   - Removed `#finally()`
 
 
 ## v3.0.0-beta-3

javascript/node/selenium-webdriver/edge.js

@@ -278,11 +278,10 @@ class Driver extends webdriver.WebDriver {
     var driver = webdriver.WebDriver.createSession(executor, caps, opt_flow);
     super(driver.getSession(), executor, driver.controlFlow());
 
-    var boundQuit = this.quit.bind(this);
-
     /** @override */
-    this.quit = function() {
-      return boundQuit().finally(service.kill.bind(service));
+    this.quit = () => {
+      return /** @type {!promise.Thenable} */(
+          promise.finally(super.quit(), service.kill.bind(service)));
     };
   }
 

javascript/node/selenium-webdriver/firefox/index.js

@@ -622,7 +622,8 @@ class Driver extends webdriver.WebDriver {
 
     /** @override */
     this.quit = () => {
-      return super.quit().finally(spec.onQuit);
+      return /** @type {!promise.Thenable} */(
+          promise.finally(super.quit(), spec.onQuit));
     };
   }
 

javascript/node/selenium-webdriver/http/util.js

@@ -61,38 +61,54 @@ exports.getStatus = getStatus;
  * Waits for a WebDriver server to be healthy and accepting requests.
  * @param {string} url Base URL of the server to query.
  * @param {number} timeout How long to wait for the server.
- * @return {!promise.Promise} A promise that will resolve when the
- *     server is ready.
+ * @param {Promise=} opt_cancelToken A promise used as a cancellation signal:
+ *     if resolved before the server is ready, the wait will be terminated
+ *     early with a {@link promise.CancellationError}.
+ * @return {!Promise} A promise that will resolve when the server is ready, or
+ *     if the wait is cancelled.
  */
-exports.waitForServer = function(url, timeout) {
-  var ready = promise.defer(),
-      start = Date.now();
-  checkServerStatus();
-  return ready.promise;
-
-  function checkServerStatus() {
-    return getStatus(url).then(status => ready.fulfill(status), onError);
-  }
-
-  function onError(e) {
-    // Some servers don't support the status command. If they are able to
-    // response with an error, then can consider the server ready.
-    if (e instanceof error.UnsupportedOperationError) {
-      ready.fulfill();
-      return;
+exports.waitForServer = function(url, timeout, opt_cancelToken) {
+  return new Promise((onResolve, onReject) => {
+    let start = Date.now();
+
+    let done = false;
+    let resolve = (status) => {
+      done = true;
+      onResolve(status);
+    };
+    let reject = (err) => {
+      done = true;
+      onReject(err);
+    };
+
+    if (opt_cancelToken) {
+      opt_cancelToken.then(_ => reject(new promise.CancellationError));
     }
 
-    if (Date.now() - start > timeout) {
-      ready.reject(
-          Error('Timed out waiting for the WebDriver server at ' + url));
-    } else {
-      setTimeout(function() {
-        if (ready.promise.isPending()) {
-          checkServerStatus();
-        }
-      }, 50);
+    checkServerStatus();
+    function checkServerStatus() {
+      return getStatus(url).then(status => resolve(status), onError);
     }
-  }
+
+    function onError(e) {
+      // Some servers don't support the status command. If they are able to
+      // response with an error, then can consider the server ready.
+      if (e instanceof error.UnsupportedOperationError) {
+        resolve({});
+        return;
+      }
+
+      if (Date.now() - start > timeout) {
+        reject(Error('Timed out waiting for the WebDriver server at ' + url));
+      } else {
+        setTimeout(function() {
+          if (!done) {
+            checkServerStatus();
+          }
+        }, 50);
+      }
+    }
+  });
 };
 
 
@@ -101,39 +117,59 @@ exports.waitForServer = function(url, timeout) {
  * timeout expires.
  * @param {string} url The URL to poll.
  * @param {number} timeout How long to wait, in milliseconds.
- * @return {!promise.Promise} A promise that will resolve when the
- *     URL responds with 2xx.
+ * @param {Promise=} opt_cancelToken A promise used as a cancellation signal:
+ *     if resolved before the a 2xx response is received, the wait will be
+ *     terminated early with a {@link promise.CancellationError}.
+ * @return {!Promise} A promise that will resolve when a 2xx is received from
+ *     the given URL, or if the wait is cancelled.
  */
-exports.waitForUrl = function(url, timeout) {
-  var client = new HttpClient(url),
-      request = new HttpRequest('GET', ''),
-      ready = promise.defer(),
-      start = Date.now();
-  testUrl();
-  return ready.promise;
-
-  function testUrl() {
-    client.send(request).then(onResponse, onError);
-  }
-
-  function onError() {
-    if (Date.now() - start > timeout) {
-      ready.reject(Error(
-          'Timed out waiting for the URL to return 2xx: ' + url));
-    } else {
-      setTimeout(function() {
-        if (ready.promise.isPending()) {
-          testUrl();
-        }
-      }, 50);
+exports.waitForUrl = function(url, timeout, opt_cancelToken) {
+  return new Promise((onResolve, onReject) => {
+    let client = new HttpClient(url);
+    let request = new HttpRequest('GET', '');
+    let start = Date.now();
+
+    let done = false;
+    let resolve = () => {
+      done = true;
+      onResolve();
+    };
+    let reject = (err) => {
+      done = true;
+      onReject(err);
+    };
+
+    if (opt_cancelToken) {
+      opt_cancelToken.then(_ => reject(new promise.CancellationError));
+    }
+
+    testUrl();
+
+    function testUrl() {
+      client.send(request).then(onResponse, onError);
+    }
+
+    function onError() {
+      if (Date.now() - start > timeout) {
+        reject(Error('Timed out waiting for the URL to return 2xx: ' + url));
+      } else {
+        setTimeout(function() {
+          if (!done) {
+            testUrl();
+          }
+        }, 50);
+      }
     }
-  }
 
-  function onResponse(response) {
-    if (!ready.promise.isPending()) return;
-    if (response.status > 199 && response.status < 300) {
-      return ready.fulfill();
+    function onResponse(response) {
+      if (done) {
+        return;
+      }
+      if (response.status > 199 && response.status < 300) {
+        resolve();
+        return;
+      }
+      onError();
     }
-    onError();
-  }
+  });
 };

javascript/node/selenium-webdriver/ie.js

@@ -420,11 +420,10 @@ class Driver extends webdriver.WebDriver {
 
     super(driver.getSession(), executor, driver.controlFlow());
 
-    let boundQuit = this.quit.bind(this);
-
     /** @override */
-    this.quit = function() {
-      return boundQuit().finally(service.kill.bind(service));
+    this.quit = () => {
+      return /** @type {!promise.Thenable} */(
+          promise.finally(super.quit(), service.kill.bind(service)));
     };
   }