js: In promise.ControlFlow#wait(), if the timeout is omitted or 0, wait

indefinitely for the condition to be satisfied.

Fixes #337

Author: jleyba

javascript/node/selenium-webdriver/CHANGES.md

@@ -1,5 +1,7 @@
 ## v2.46.0-dev
 
+* FIXED: `promise.ControlFlow#wait()` now has consistent semantics for an
+    omitted or 0-timeout: it will wait indefinitely.
 * FIXED: `remote.DriverService#start()` will now fail if the child process dies
     while waiting for the server to start accepting requests. Previously, start
     would continue to poll the server address until the timeout expired.

javascript/webdriver/promise.js

@@ -1544,15 +1544,18 @@ promise.ControlFlow.prototype.timeout = function(ms, opt_description) {
  * If the condition function throws, or returns a rejected promise, the
  * wait task will fail.
  *
- * If the condition is defined as a promise, the flow will block on that
- * promise's resolution, up to {@code timeout} milliseconds. If
- * {@code timeout === 0}, the flow will block indefinitely on the promise's
- * resolution.
+ * If the condition is defined as a promise, the flow will wait for it to
+ * settle. If the timeout expires before the promise settles, the promise
+ * returned by this function will be rejected.
+ *
+ * If this function is invoked with `timeout === 0`, or the timeout is omitted,
+ * the flow will wait indefinitely for the condition to be satisfied.
  *
  * @param {(!promise.Promise<T>|function())} condition The condition to poll,
  *     or a promise to wait on.
  * @param {number=} opt_timeout How long to wait, in milliseconds, for the
- *     condition to hold before timing out; defaults to 0.
+ *     condition to hold before timing out. If omitted, the flow will wait
+ *     indefinitely.
  * @param {string=} opt_message An optional error message to include if the
  *     wait times out; defaults to the empty string.
  * @return {!promise.Promise<T>} A promise that will be fulfilled
@@ -1618,7 +1621,7 @@ promise.ControlFlow.prototype.wait = function(
           var elapsed = goog.now() - startTime;
           if (!!value) {
             fulfill(value);
-          } else if (elapsed >= timeout) {
+          } else if (timeout && elapsed >= timeout) {
             reject(new Error((opt_message ? opt_message + '\n' : '') +
                 'Wait timed out after ' + elapsed + 'ms'));
           } else {

javascript/webdriver/test/promise_flow_test.js

@@ -1114,13 +1114,44 @@ function testWaiting_pollingLoopWaitsForAllScheduledTasksInCondition() {
 }
 
 
-function testWaiting_timesOut_zeroTimeout() {
-  scheduleWait(function() { return false; }, 0, 'always false');
-  return waitForAbort().then(function(e) {
-    assertRegExp(/^always false\nWait timed out after \d+ms$/, e.message);
+function testWaiting_waitsForeverOnAZeroTimeout() {
+  var done = false;
+  setTimeout(function() {
+    done = true;
+  }, 500);
+  var waitResult = scheduleWait(function() {
+    return done;
+  }, 0);
+
+  return timeout(250).then(function() {
+    assertFalse(done);
+    return timeout(300);
+  }).then(function() {
+    assertTrue(done);
+    return waitResult;
   });
 }
 
+
+function testWaiting_waitsForeverIfTimeoutOmitted() {
+  var done = false;
+  setTimeout(function() {
+    done = true;
+  }, 500);
+  var waitResult = scheduleWait(function() {
+    return done;
+  });
+
+  return timeout(250).then(function() {
+    assertFalse(done);
+    return timeout(300);
+  }).then(function() {
+    assertTrue(done);
+    return waitResult;
+  });
+}
+
+
 function testWaiting_timesOut_nonZeroTimeout() {
   var count = 0;
   scheduleWait(function() {