factorio-clusterio/lib/stringUtils.spec.js

const assert = require("assert");
const stringUtils = require("./stringUtils");

describe("stringUtils.js", function(){
	describe("hashCode", function(){
		it("Produces a 32bit signed int hash from a string", function(){
			let x = stringUtils.hashCode("whatever");
			let y = stringUtils.hashCode(" a much longer string to prove this works for long strings as well and also special characters &!¤(#)¤");
			
			assert(typeof x == "number", "hashCode should be returning a 32 bit signed int");
			assert(x.toString() == "1934383586");
			assert(y.toString() == "1648886132");
		});
		let permutations = 1000;
		it("Rarely produces same hash for different strings ("+permutations+" hashes with collision check)", function(){
			let keyHashPairs = [];
			for(let i = 0; i < permutations; i++){
				let string = Math.random().toString();
				keyHashPairs.push({
					key:string,
					hash:stringUtils.hashCode(string),
				});
			}
			
			for(let i = 0; i < permutations; i++){
				for(let o = 0; o < permutations; o++){
					assert(i == o || keyHashPairs[o].key != keyHashPairs[i].key, "Woha, Math.random() generated 2 equal numbers???");
					assert(i == o || keyHashPairs[o].hash != keyHashPairs[i].hash, "Hash collision, as long at it doesn't happen again its fine.");
				}
			}
		});
		it("Returns 0 for 0 length strings", function(){
			let x = stringUtils.hashCode("");
			assert.deepEqual(x, 0);
		});
		it("Throws when supplied with anything other than a string", function(){
			assert.throws(function(){
				stringUtils.hashCode([]);
			}, "ERROR: Not a string")
			assert.throws(function(){
				stringUtils.hashCode({});
			}, "ERROR: Not a string")
			assert.throws(function(){
				stringUtils.hashCode(0);
			}, "ERROR: Not a string")
		});
	});
});