discourse/test/javascripts/components/debounce_test.js

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2013-10-02 14:03:04 -04:00
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");
});