1 files changed, 113 insertions, 0 deletions
diff --git a/javascript/videojs/test/unit/utils/fn.test.js b/javascript/videojs/test/unit/utils/fn.test.js
new file mode 100644
index 0000000..9ff23c7
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+++ b/javascript/videojs/test/unit/utils/fn.test.js
@@ -0,0 +1,113 @@
+/* eslint-env qunit */
+import sinon from 'sinon';
+import * as Fn from '../../../src/js/utils/fn';
+
+QUnit.module('utils/fn', {
+  beforeEach() {
+    this.clock = sinon.useFakeTimers();
+  },
+  afterEach() {
+    this.clock.restore();
+  }
+});
+
+QUnit.test('should add context to a function', function(assert) {
+  assert.expect(1);
+
+  const newContext = { test: 'obj'};
+  const asdf = function() {
+    assert.ok(this === newContext);
+  };
+  const fdsa = Fn.bind_(newContext, asdf);
+
+  fdsa();
+});
+
+QUnit.test('should throttle functions properly', function(assert) {
+  assert.expect(3);
+
+  const tester = sinon.spy();
+  const throttled = Fn.throttle(tester, 100);
+
+  // We must wait a full wait period before the function can be called.
+  this.clock.tick(100);
+  throttled();
+  throttled();
+  this.clock.tick(50);
+  throttled();
+
+  assert.strictEqual(tester.callCount, 1, 'the throttled function has been called the correct number of times');
+
+  this.clock.tick(50);
+  throttled();
+
+  assert.strictEqual(tester.callCount, 2, 'the throttled function has been called the correct number of times');
+
+  throttled();
+  this.clock.tick(100);
+  throttled();
+
+  assert.strictEqual(tester.callCount, 3, 'the throttled function has been called the correct number of times');
+});
+
+QUnit.test('should debounce functions properly', function(assert) {
+  assert.expect(6);
+
+  const tester = sinon.spy();
+  const debounced = Fn.debounce(tester, 100);
+
+  // Called twice on each assertion to ensure that multiple calls only result
+  // in a call to the inner function.
+  debounced();
+  debounced();
+  assert.strictEqual(tester.callCount, 0, 'the debounced function was NOT called because no time has elapsed');
+
+  this.clock.tick(100);
+  assert.strictEqual(tester.callCount, 1, 'the debounced function was called because enough time elapsed');
+
+  this.clock.tick(100);
+  assert.strictEqual(tester.callCount, 1, 'the debounced function was NOT called again even though time elapsed');
+
+  debounced();
+  debounced();
+  assert.strictEqual(tester.callCount, 1, 'the debounced function was NOT called because no time has elapsed since invocation');
+
+  this.clock.tick(50);
+  assert.strictEqual(tester.callCount, 1, 'the debounced function was NOT called because the clock has NOT ticket forward enough');
+
+  this.clock.tick(50);
+  assert.strictEqual(tester.callCount, 2, 'the debounced function was called because the clock ticked forward enough');
+});
+
+QUnit.test('may immediately invoke debounced functions', function(assert) {
+  assert.expect(2);
+
+  const tester = sinon.spy();
+  const debounced = Fn.debounce(tester, 100, true);
+
+  // Called twice on each assertion to ensure that multiple calls only result
+  // in a call to the inner function.
+  debounced();
+  debounced();
+  assert.strictEqual(tester.callCount, 1, 'the debounced function was called because true was passed');
+
+  this.clock.tick(100);
+  assert.strictEqual(tester.callCount, 1, 'the debounced function was NOT called because it has only been invoked once');
+});
+
+QUnit.test('may cancel debounced functions', function(assert) {
+  assert.expect(2);
+
+  const tester = sinon.spy();
+  const debounced = Fn.debounce(tester, 100);
+
+  debounced();
+  this.clock.tick(50);
+  debounced.cancel();
+  this.clock.tick(50);
+  assert.strictEqual(tester.callCount, 0, 'the debounced function was NOT called because it was cancelled');
+
+  debounced();
+  this.clock.tick(100);
+  assert.strictEqual(tester.callCount, 1, 'the debounced function was called because it was NOT cancelled');
+});