From 4fc4831efce80e7b043a145b7db0e030e158a564 Mon Sep 17 00:00:00 2001
From: Wojciech Zawistowski <wojciech.zawistowski@gmail.com>
Date: Wed, 2 Oct 2013 20:03:04 +0200
Subject: [PATCH] adds unit tests for Discourse.debounce

---
 test/javascripts/components/debounce_test.js | 86 ++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 test/javascripts/components/debounce_test.js

diff --git a/test/javascripts/components/debounce_test.js b/test/javascripts/components/debounce_test.js
new file mode 100644
index 000000000..98c7550b9
--- /dev/null
+++ b/test/javascripts/components/debounce_test.js
@@ -0,0 +1,86 @@
+var clock, original, debounced;
+
+var firedOnce = function(message) {
+  ok(original.calledOnce, message);
+};
+
+var notFired = function(message) {
+  ok(!original.called, message);
+};
+
+module("Discourse.debounce", {
+  setup: function() {
+    clock = sinon.useFakeTimers();
+    original = sinon.spy();
+    debounced = Discourse.debounce(original, 100);
+  },
+
+  teardown: function() {
+    clock.restore();
+  }
+});
+
+test("delays function execution till the end of the timeout", function() {
+  debounced();
+  notFired("immediately after calling debounced function nothing happens");
+
+  clock.tick(99);
+  notFired("just before the end of the timeout still nothing happens");
+
+  clock.tick(1);
+  firedOnce("exactly at the end of the timeout the function is executed");
+});
+
+test("executes delayed function only once, no matter how many times debounced function is called during the timeout", function() {
+  debounced();
+  debounced();
+
+  clock.tick(100);
+  firedOnce("second call was supressed");
+});
+
+test("does not prolong the timeout when the debounced function is called for the second time during the timeout", function() {
+  debounced();
+
+  clock.tick(50);
+  debounced();
+
+  clock.tick(50);
+  firedOnce("function is executed exactly at the end of the original timeout");
+});
+
+test("returns a JS timer handle that allows delayed execution to be cancelled before the timeout ends", function() {
+  var timerId = debounced();
+
+  clock.tick(50);
+  clearTimeout(timerId);
+
+  clock.tick(50);
+  notFired("timeout has ended but function was not executed");
+});
+
+test("preserves first call's context and params when executing delayed function", function() {
+  var firstObj = {};
+  var secondObj = {};
+
+  debounced.call(firstObj, "first");
+  debounced.call(secondObj, "second");
+
+  clock.tick(100);
+  ok(original.calledOn(firstObj), "the context of the first of two subsequent calls is preserved");
+  ok(original.calledWithExactly("first"), "param passed during the first of two subsequent calls is preserved");
+});
+
+test("can be called again (with a different context and params) after timeout passes", function() {
+  var firstObj = {};
+  var secondObj = {};
+
+  debounced.call(firstObj, "first");
+
+  clock.tick(100);
+  debounced.call(secondObj, "second");
+
+  clock.tick(100);
+  ok(original.calledOn(secondObj), "function is executed with the context of the call made after the timeout has passed");
+  ok(original.calledWithExactly("second"), "function is executed with the param passed to the call made after the timeout has passed");
+});