removed null as a type of previousTokens

Author: jondeweydev

src/@types/rateLimit.d.ts

@@ -25,8 +25,7 @@ export interface RedisBucket {
 
 export interface RedisWindow {
     currentTokens: number;
-    // null if limiter is currently on the initial fixed window
-    previousTokens: number | null;
+    previousTokens: number;
     fixedWindowStart?: number;
 }
 

test/rateLimiters/slidingWindowCounter.test.ts

@@ -28,14 +28,14 @@ async function setTokenCountInClient(
     redisClient: ioredis.Redis,
     uuid: string,
     currentTokens: number,
-    previousTokens: number | null,
+    previousTokens: number,
     fixedWindowStart: number
 ) {
     const value: RedisWindow = { currentTokens, previousTokens, fixedWindowStart };
     await redisClient.set(uuid, JSON.stringify(value));
 }
 
-xdescribe('Test TokenBucket Rate Limiter', () => {
+xdescribe('Test SlidingWindowCounter Rate Limiter', () => {
     beforeEach(async () => {
         // init a mock redis cache
         client = new RedisMock();
@@ -50,14 +50,29 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
             afterEach(() => {
                 client.flushall();
             });
+
             test('fixed window is initially empty', async () => {
+                setTokenCountInClient(client, user1, 0, 0, timestamp);
+
+                // window is intially empty
+                const withdraw5 = 5;
+                expect((await limiter.processRequest(user1, timestamp, withdraw5)).tokens).toBe(
+                    CAPACITY - withdraw5
+                );
+                const tokenCountFull = await getWindowFromClient(client, user1);
+                expect(tokenCountFull.currentTokens).toBe(CAPACITY - withdraw5);
+                expect(tokenCountFull.previousTokens).toBe(0);
+            });
+
+            test('fixed window and cache are initially empty', async () => {
                 // window is intially empty
                 const withdraw5 = 5;
                 expect((await limiter.processRequest(user1, timestamp, withdraw5)).tokens).toBe(
                     CAPACITY - withdraw5
                 );
                 const tokenCountFull = await getWindowFromClient(client, user1);
                 expect(tokenCountFull.currentTokens).toBe(CAPACITY - withdraw5);
+                expect(tokenCountFull.previousTokens).toBe(0);
             });
 
             test('fixed window is partially full and request has leftover tokens', async () => {
@@ -80,15 +95,15 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
             // window partially full and no leftover tokens after request
             test('fixed window is partially full and request has no leftover tokens', async () => {
                 const initial = 6;
-                await setTokenCountInClient(client, user2, initial, null, timestamp);
+                await setTokenCountInClient(client, user2, initial, 0, timestamp);
                 expect((await limiter.processRequest(user2, timestamp, initial)).tokens).toBe(0);
                 const tokenCountPartialToEmpty = await getWindowFromClient(client, user2);
                 expect(tokenCountPartialToEmpty.currentTokens).toBe(0);
             });
 
             // Window initially full but enough time elapsed to paritally fill window since last request
-            test('fixed window is initially full but after new fixed window is initialized request is allowed', async () => {
-                await setTokenCountInClient(client, user4, 10, null, timestamp);
+            test('current window is initially full but after new fixed window is initialized request is allowed', async () => {
+                await setTokenCountInClient(client, user4, 10, 0, timestamp);
                 // tokens returned in processRequest is equal to the capacity
                 // still available in the fixed window
                 expect(
@@ -111,7 +126,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
                 // to set rolling window at 75% of previous fixed window)
 
                 // to set initial fixedWindowStart
-                await setTokenCountInClient(client, user4, 0, null, timestamp);
+                await setTokenCountInClient(client, user4, 0, 0, timestamp);
 
                 // large request at very end of first fixed window
                 await limiter.processRequest(user4, timestamp + WINDOW_SIZE, 8);
@@ -135,7 +150,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
                 // to set rolling window at 50% of previous fixed window)
 
                 // to set initial fixedWindowStart
-                await setTokenCountInClient(client, user4, 0, null, timestamp);
+                await setTokenCountInClient(client, user4, 0, 0, timestamp);
 
                 // large request at very end of first fixed window
                 await limiter.processRequest(user4, timestamp + WINDOW_SIZE, 8);
@@ -159,7 +174,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
                 // to set rolling window at 25% of previous fixed window)
 
                 // to set initial fixedWindowStart
-                await setTokenCountInClient(client, user4, 0, null, timestamp);
+                await setTokenCountInClient(client, user4, 0, 0, timestamp);
 
                 // large request at very end of first fixed window
                 await limiter.processRequest(user4, timestamp + WINDOW_SIZE, 8);
@@ -193,7 +208,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
             test('window is partially full but not enough time elapsed to reach new window', async () => {
                 const initRequest = 6;
 
-                await setTokenCountInClient(client, user2, initRequest, null, timestamp);
+                await setTokenCountInClient(client, user2, initRequest, 0, timestamp);
                 // expect remaining tokens to be 4, b/c the 5 token request should be blocked
                 expect(
                     (await limiter.processRequest(user2, timestamp + WINDOW_SIZE, 5)).tokens
@@ -210,7 +225,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
                 // to set rolling window at 75% of previous fixed window)
 
                 // to set initial fixedWindowStart
-                await setTokenCountInClient(client, user4, 0, null, timestamp);
+                await setTokenCountInClient(client, user4, 0, 0, timestamp);
 
                 const initRequest = 8;
 
@@ -236,7 +251,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
             // to set rolling window at 50% of previous fixed window)
 
             // to set initial fixedWindowStart
-            await setTokenCountInClient(client, user4, 0, null, timestamp);
+            await setTokenCountInClient(client, user4, 0, 0, timestamp);
 
             const initRequest = 8;
 
@@ -261,7 +276,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
             // to set rolling window at 25% of previous fixed window)
 
             // to set initial fixedWindowStart
-            await setTokenCountInClient(client, user4, 0, null, timestamp);
+            await setTokenCountInClient(client, user4, 0, 0, timestamp);
 
             const initRequest = 8;
 
@@ -308,7 +323,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
             // Fill up user 1's window
             const value: RedisWindow = {
                 currentTokens: 10,
-                previousTokens: null,
+                previousTokens: 0,
                 fixedWindowStart: timestamp,
             };
             await client.set(user1, JSON.stringify(value));
@@ -321,7 +336,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
         });
 
         test('fixed window and current/previous tokens update as expected', async () => {
-            await setTokenCountInClient(client, user1, 0, null, timestamp);
+            await setTokenCountInClient(client, user1, 0, 0, timestamp);
             // fills first window with 4 tokens
             await limiter.processRequest(user1, timestamp, 5);
             // fills second window with 5 tokens
@@ -367,7 +382,7 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
             const requested = 6;
             const user3Tokens = 8;
             // Add tokens for user 3 so we have both a user that exists in the store (3) and one that doesn't (2)
-            await setTokenCountInClient(client, user3, user3Tokens, null, timestamp);
+            await setTokenCountInClient(client, user3, user3Tokens, 0, timestamp);
 
             // issue a request for user 1;
             await limiter.processRequest(user1, timestamp, requested);
@@ -401,9 +416,9 @@ xdescribe('Test TokenBucket Rate Limiter', () => {
 
         test('all windows should be able to be reset', async () => {
             const tokens = 5;
-            await setTokenCountInClient(client, user1, tokens, null, timestamp);
-            await setTokenCountInClient(client, user2, tokens, null, timestamp);
-            await setTokenCountInClient(client, user3, tokens, null, timestamp);
+            await setTokenCountInClient(client, user1, tokens, 0, timestamp);
+            await setTokenCountInClient(client, user2, tokens, 0, timestamp);
+            await setTokenCountInClient(client, user3, tokens, 0, timestamp);
 
             limiter.reset();