test: add cases for array/shuffle

test/array/shuffle.js

@@ -0,0 +1,66 @@
+"use strict";
+
+var assert  = require("chai").assert
+  , shuffle = require("../../array/shuffle");
+
+describe("array/shuffle", function () {
+	var array = [1, 2, 3];
+
+	// Adopt from lodash.shuffle
+	// https://github.com/lodash/lodash/blob/master/test/shuffle.js
+	it("should throw TypeError for non array input", function () {
+		try {
+			shuffle();
+		} catch (e) {
+			assert.strictEqual(e.name, "TypeError");
+			assert.strictEqual(e.message, "input must be an Array, got undefined!");
+		}
+
+		try {
+			shuffle({});
+		} catch (e) {
+			assert.strictEqual(e.name, "TypeError");
+			assert.strictEqual(e.message, "input must be an Array, got object!");
+		}
+
+		try {
+			shuffle(1);
+		} catch (e) {
+			assert.strictEqual(e.name, "TypeError");
+			assert.strictEqual(e.message, "input must be an Array, got number!");
+		}
+	});
+
+	it("should return a new array", function () { assert.notStrictEqual(shuffle(array), array); });
+
+	it("should contain the same elements after a collection is shuffled", function () {
+		assert.deepStrictEqual(shuffle(array).sort(), array);
+	});
+
+	// Adopt from fast-shuffle
+	// https://github.com/philihp/fast-shuffle/blob/master/src/__tests__/index.test.js
+	it("does not mutate the source", function () {
+		var d1 = ["A", "B", "C", "D", "E", "F", "G", "H"];
+		shuffle(d1);
+
+		assert.deepStrictEqual(d1, ["A", "B", "C", "D", "E", "F", "G", "H"]);
+	});
+
+	it("does a shallow clone", function () {
+		var d1 = [
+			{ name: "Alice", money: 10 }, { name: "Betty", money: 20 }, { name: "Cindy", money: 15 }
+		];
+		var d2 = shuffle(d1);
+
+		assert.include(d2, d1[0]);
+		assert.include(d2, d1[1]);
+		assert.include(d2, d1[2]);
+	});
+
+	it("works with massive noise", function () {
+		var d1 = new Array(500).fill().map(function (_, i) { return i; });
+		var d2 = shuffle(d1);
+
+		assert.deepStrictEqual(d1.sort(), d2.sort());
+	});
+});