Add countTimers method

Readme.md

@@ -200,6 +200,11 @@ available in both browser & node environments.
 
 Cancels the callback scheduled by the provided id.
 
+### `clock.countTimers()`
+
+Returns the number of waiting timers. This can be used to assert that a test
+finishes without leaking any timers.
+
 ### `clock.hrtime(prevTime?)`
 Only available in Node.js, mimicks process.hrtime().
 

src/lolex-src.js

@@ -257,7 +257,6 @@ function withGlobal(_global) {
  return timer.id;
  }
 
-
  /* eslint consistent-return: "off" */
  function compareTimers(a, b) {
  // Sort first by absolute timing
@@ -574,6 +573,10 @@ function withGlobal(_global) {
  return clearTimer(clock, timerId, "Immediate");
  };
 
+ clock.countTimers = function countTimers() {
+ return Object.keys(clock.timers || {}).length;
+ };
+
  clock.requestAnimationFrame = function requestAnimationFrame(func) {
  var result = addTimer(clock, {
  func: func,

test/lolex-test.js

@@ -432,6 +432,26 @@ describe("lolex", function () {
 
  });
 
+ describe("countTimers", function () {
+
+ beforeEach(function () {
+ this.clock = lolex.createClock();
+ });
+
+ it("return zero for a fresh clock", function () {
+ assert.equals(this.clock.countTimers(), 0);
+ });
+
+ it("counts remaining timers", function () {
+ this.clock.setTimeout(NOOP, 100);
+ this.clock.setTimeout(NOOP, 200);
+ this.clock.setTimeout(NOOP, 300);
+ this.clock.tick(150);
+ assert.equals(this.clock.countTimers(), 2);
+ });
+
+ });
+
  describe("tick", function () {
 
  beforeEach(function () {