Add tests and correct bugs

Author: Pavan-Rana

go.mod

@@ -6,5 +6,5 @@ require (
     github.com/prometheus/client_golang v1.19.0
     github.com/redis/go-redis/v9 v9.5.1
     google.golang.org/grpc v1.63.2
-    google.golang.org/protbuf v1.34.1
+    google.golang.org/protobuf v1.34.1
 )

go.sum

@@ -0,0 +1,10 @@
+github.com/prometheus/client_golang v1.19.0 h1:ygXvpU1AoN1MhdzckN+PyD9QJOSD4x7kmXYlnfbA6JU=
+github.com/prometheus/client_golang v1.19.0/go.mod h1:ZRM9uEAypZakd+q/x7+gmsvXdURP+DABIEIjnmDdp+k=
+github.com/redis/go-redis/v9 v9.5.1 h1:H1X4D3yHPaYrkL5X06Wh6xNVM/pX0Ft4RV0vMGvLBh8=
+github.com/redis/go-redis/v9 v9.5.1/go.mod h1:hdY0cQFCN4fnSYT6TkisLufl/4W5UIXyv0b/CLO2V2M=
+google.golang.org/grpc v1.63.2 h1:MUeiw1B2maTVZthpU5xvASfTh3LDbxHd6IJ6QQVU+xM=
+google.golang.org/grpc v1.63.2/go.mod h1:WAX/8DgncnokcFUldAxq7GeB5DXHDbMF+lLvDomNkRA=
+google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
+google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
+google.golang.org/protobuf v1.34.1 h1:9ddQBjfCyZPOHPUiPxpYESBLc+T8P3E+Vo4IbKZgFWg=
+google.golang.org/protobuf v1.34.1/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=

internal/algorithm/sliding_window.go

@@ -16,11 +16,11 @@ type SlidingWindow struct {
 	window 	 time.Duration
 }
 
-func NewSlidingWindoe(limit int, window time.Duration) *SlidingWindow {
+func NewSlidingWindow(limit int, window time.Duration) *SlidingWindow {
 	return &SlidingWindow{limit: limit, window: window}
 }
 
-func (sw: *SlidingWindow) Allow() bool {
+func (sw *SlidingWindow) Allow() bool {
 	sw.mu.Lock()
 	defer sw.mu.Unlock()
 

internal/algorithm/sliding_window_test.go

@@ -1 +1,67 @@
-// internal/algorithm/sliding_window_test.go
+package algorithm_test
+
+import (
+	"sync"
+	"time"
+	"testing"
+
+	"github.com/Pavan-Rana/rate-limiter/internal/algorithm"
+)
+
+func TestSlidingWindow_BasicLimit(t *testing.T) {
+	sw := algorithm.NewSlidingWindow(5, time.Second)
+
+	for i := 0; i < 5; i++ {
+		if !sw.Allow() {
+			t.Fatalf("Expected request %d to be allowed", i+1)
+		}
+	}
+	if sw.Allow() {
+		t.Fatal("Expected 6th request to be rejected")
+	}
+}
+
+func TestSlidingWindow_WindowExpiry(t *testing.T) {
+	sw := algorithm.NewSlidingWindow(3, 100*time.Millisecond)
+
+	for i := 0; i < 3; i++ {
+		sw.Allow()
+	}
+	if sw.Allow() {
+		t.Fatal("Expected 4th request to be rejected")
+	}
+
+	time.Sleep(110 * time.Millisecond)
+
+	if !sw.Allow(){
+		t.Fatal("Expected request to be allowed after window expiry")
+	}
+}
+
+func TestSlidingWindow_ConcurrentAccess(t *testing.T) {
+	const limit = 100
+	sw := algorithm.NewSlidingWindow(limit, time.Second)
+
+	var (
+		wg 		sync.WaitGroup
+		mu 		sync.Mutex
+		allowed int
+	)
+
+	for i := 0; i < limit; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			if sw.Allow() {
+				mu.Lock()
+				allowed++
+				mu.Unlock()
+			}
+		}()
+	}
+	wg.Wait()
+
+	if allowed > limit {
+		t.Fatalf("Allowed %d requests, limit is %d", allowed, limit)
+	}
+}

internal/algorithm/token_bucket.go

@@ -11,15 +11,15 @@ type TokenBucket struct {
 	tokens		 float64
 	capacity	 float64
 	rate		 float64 // tokens per second
-	lastFillTime time.Time
+	lastFill 	 time.Time
 }
 
-func NewTokenBucet(capacity float64, ratePerSec float64) *TokenBucket {
+func NewTokenBucket(capacity float64, ratePerSec float64) *TokenBucket {
 	return &TokenBucket{
 		tokens:		 capacity,
 		capacity:	 capacity,
 		rate:		 ratePerSec,
-		lastFillTime: time.Now(),
+		lastFill: time.Now(),
 	}
 }
 
@@ -28,7 +28,7 @@ func (tb *TokenBucket) Allow() bool {
 	defer tb.mu.Unlock()
 
 	now := time.Now()
-	elapsed := now.Sub(tb.lastFillTime).Seconds()
+	elapsed := now.Sub(tb.lastFill).Seconds()
 	tb.tokens = minF(tb.capacity, tb.tokens+elapsed*tb.rate)
 	tb.lastFill = now