chore(tests2png): add exhaust PNG diagram

Add test to draw PNG diagram for exhaust. Change painter.js to support exhaust (use case where an
inner Observable is emitted but never subscribed to).

spec/helpers/tests2png/painter.js

@@ -351,6 +351,14 @@ function addGhostInnerInputs(inputStreams) {
  var message = inputStream.messages[j];
  if (isNestedStreamData(message) && typeof message.isGhost !== 'boolean') {
  var referenceTime = message.frame;
+ if (!message.notification.value.subscription) {
+ // There was no subscription at all, so this nested Observable is ghost
+ message.isGhost = true;
+ message.notification.value.isGhost = true;
+ message.frame = referenceTime;
+ message.notification.value.subscription = { start: referenceTime, end: 0 };
+ continue;
+ }
  var subscriptionTime = message.notification.value.subscription.start;
  if (referenceTime !== subscriptionTime) {
  message.isGhost = false;

spec/operators/exhaust-spec.js

@@ -6,6 +6,16 @@ var Observable = Rx.Observable;
 var queueScheduler = Rx.Scheduler.queue;
 
 describe('Observable.prototype.exhaust()', function () {
+ it.asDiagram('exhaust')('should handle a hot observable of hot observables', function () {
+ var x = cold( '--a---b---c--| ');
+ var y = cold( '---d--e---f---| ');
+ var z = cold( '---g--h---i---|');
+ var e1 = hot( '------x-------y-----z-------------|', { x: x, y: y, z: z });
+ var expected = '--------a---b---c------g--h---i---|';
+
+ expectObservable(e1.exhaust()).toBe(expected);
+ });
+
  it('should switch to first immediately-scheduled inner Observable', function () {
  var e1 = cold( '(ab|)');
  var e1subs = '(^!)';