Add a way to print messages, and add a proper test for rate limiting

tests/test.js

@@ -3,8 +3,12 @@ const { RateLimiter } = require("../generated/ratelimiter");
 
 async function asyncRunTest(fn, ...args) {
 	try {
-		await fn(...args);
+		let msg = await fn(...args);
-		console.log(`✅ ${fn.name}(${args})`)
+		if (msg) {
+			console.log(`✅ ${fn.name}(${args}): ${msg}`);
+		} else {
+			console.log(`✅ ${fn.name}(${args})`);
+		}
 	} catch (ex) {
 		console.log(`❌ ${fn.name}(${args})`)
 		console.error(ex);
@@ -13,14 +17,25 @@ async function asyncRunTest(fn, ...args) {
 }
 function runTest(fn, ...args) {
 	try {
-		fn(...args);
+		let msg = fn(...args);
+		if (msg) {
+			console.log(`✅ ${fn.name}(${args}): ${msg}`);
+		} else {
 			console.log(`✅ ${fn.name}(${args})`);
+		}
 	} catch (ex) {
 		console.log(`❌ ${fn.name}(${args})`);
 		console.error(ex);
 		process.exitCode++;
 	}
 }
+async function delay(time) {
+	await new Promise((resolve, reject) => {
+		setTimeout(() => {
+			resolve();
+		}, time);
+	});
+}
 
 function test_Construct(limit) {
 	let rl = new RateLimiter(limit);
@@ -43,6 +58,51 @@ async function test_TaskLimit(tasks, limit) {
 	}
 }
 
+async function test_LimitEnforcement(tasks, limit) {
+	let rl = new RateLimiter(limit);
+	let value = 0;
+	let time = 50;
+
+	let records = [];
+	let t = setInterval(() => {
+		records.push([
+			value, Date.now()
+		]);
+	}, 25);
+
+	let p = new Array();
+	for (let idx = 0; idx < tasks; idx++) {
+		p.push(rl.queue(async () => {
+			await delay(time);
+			value++;
+		}));
+	}
+	await Promise.all(p);
+
+	clearInterval(t);
+
+	let totalTime = 0;
+	let totalValue = 0;
+	for (let n = 1; n < records.length; n++) {
+		let pRecord = records[n - 1];
+		let cRecord = records[n];
+
+		let deltaTime = cRecord[1] - pRecord[1];
+		let deltaValue = cRecord[0] - pRecord[0];
+
+		totalTime += deltaTime;
+		totalValue += deltaValue;
+	}
+	let averageChange = totalValue / totalTime;
+	let normalizedChange = averageChange * time;
+	// setTimeout loses accuracy over time, not sure what the solution is. Accepting +-1 for now.
+	if ((normalizedChange < (limit - 1.)) || (normalizedChange > (limit + 1.))) {
+		throw new Error(`Outside acceptable range (${normalizedChange} is not equal to ${limit}).`);
+	} else {
+		return `Within acceptable range (${normalizedChange} is roughly equal to ${limit}).`
+	}
+}
+
 (async function() {
 	process.exitCode = 0;
 	for (let limit = 1; limit <= 64; limit *= 2) {
@@ -53,4 +113,7 @@ async function test_TaskLimit(tasks, limit) {
 			await asyncRunTest(test_TaskLimit, tasks, limit);
 		}
 	}
+	for (let limit = 1; limit <= 10; limit++) {
+		await asyncRunTest(test_LimitEnforcement, 100, limit);
+	}
 })();