Add http handler tests and add http handler interface

Author: Pavan-Rana

go.mod

@@ -11,10 +11,14 @@ require (
 
 require (
 	github.com/alicebob/miniredis/v2 v2.37.0 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.5.0 // indirect
+	github.com/prometheus/common v0.48.0 // indirect
+	github.com/prometheus/procfs v0.12.0 // indirect
 	github.com/stretchr/testify v1.11.1 // indirect
 	github.com/yuin/gopher-lua v1.1.1 // indirect
 	golang.org/x/net v0.21.0 // indirect

go.sum

@@ -1,5 +1,7 @@
 github.com/alicebob/miniredis/v2 v2.37.0 h1:RheObYW32G1aiJIj81XVt78ZHJpHonHLHW7OLIshq68=
 github.com/alicebob/miniredis/v2 v2.37.0/go.mod h1:TcL7YfarKPGDAthEtl5NBeHZfeUQj6OXMm/+iu5cLMM=
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
 github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
@@ -10,6 +12,12 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 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/prometheus/client_model v0.5.0 h1:VQw1hfvPvk3Uv6Qf29VrPF32JB6rtbgI6cYPYQjL0Qw=
+github.com/prometheus/client_model v0.5.0/go.mod h1:dTiFglRmd66nLR9Pv9f0mZi7B7fk5Pm3gvsjB5tr+kI=
+github.com/prometheus/common v0.48.0 h1:QO8U2CdOzSn1BBsmXJXduaaW+dY/5QLjfB8svtSzKKE=
+github.com/prometheus/common v0.48.0/go.mod h1:0/KsvlIEfPQCQ5I2iNSAWKPZziNCvRs5EC6ILDTlAPc=
+github.com/prometheus/procfs v0.12.0 h1:jluTpSng7V9hY0O2R9DzzJHYb2xULk9VTR1V1R/k6Bo=
+github.com/prometheus/procfs v0.12.0/go.mod h1:pcuDEFsWDnvcgNzo4EEweacyhjeA9Zk3cnaOZAZEfOo=
 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=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=

internal/http/handler.go

@@ -1,38 +1,42 @@
 package http
 
 import (
+	"context"
 	"encoding/json"
-	"net/http"
+	stdhttp "net/http"
 
-	"github.com/Pavan-Rana/rate-limiter/internal/limiter"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
-func NewRouter(lim *limiter.Limiter) http.Handler {
-	mux := http.NewServeMux()
+type Limiter interface {
+	AllowRequest(ctx context.Context, apiKey string) (bool, error)
+}
+
+func NewRouter(lim Limiter) stdhttp.Handler {
+	mux := stdhttp.NewServeMux()
 	mux.HandleFunc("/check", checkHandler(lim))
 	mux.Handle("/metrics", promhttp.Handler())
 	return mux
 }
 
-func checkHandler(lim *limiter.Limiter) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		if r.Method != http.MethodPost {
-			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+func checkHandler(lim Limiter) stdhttp.HandlerFunc {
+	return func(w stdhttp.ResponseWriter, r *stdhttp.Request) {
+		if r.Method != stdhttp.MethodPost {
+			stdhttp.Error(w, "Method not allowed", stdhttp.StatusMethodNotAllowed)
 			return
 		}
 
 		apiKey := r.Header.Get("X-API-Key")
 		if apiKey == "" {
-			http.Error(w, "Missing X-API-Key", http.StatusBadRequest)
+			stdhttp.Error(w, "Missing X-API-Key", stdhttp.StatusBadRequest)
 			return
 		}
 
 		allowed, _ := lim.AllowRequest(r.Context(), apiKey)
 
-		status := http.StatusOK
+		status := stdhttp.StatusOK
 		if !allowed {
-			status = http.StatusTooManyRequests
+			status = stdhttp.StatusTooManyRequests
 		}
 
 		w.Header().Set("Content-Type", "application/json")

internal/http/handler_test.go

@@ -1 +1,111 @@
-// internal/http/handler_test.go
+package http_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	stdhttp "net/http"
+	"net/http/httptest"
+	"testing"
+
+	handler "github.com/Pavan-Rana/rate-limiter/internal/http"
+)
+
+// mockLimiter implements the Limiter interface for testing
+type mockLimiter struct {
+	allow bool
+	err   error
+}
+
+func (m *mockLimiter) AllowRequest(ctx context.Context, apiKey string) (bool, error) {
+	return m.allow, m.err
+}
+
+func TestCheckHandler(t *testing.T) {
+	tests := []struct {
+		name        string
+		method      string
+		apiKey      string
+		allow       bool
+		wantStatus  int
+		wantAllowed bool
+	}{
+		{
+			name:        "allowed",
+			method:      stdhttp.MethodPost,
+			apiKey:      "abc123",
+			allow:       true,
+			wantStatus:  stdhttp.StatusOK,
+			wantAllowed: true,
+		},
+		{
+			name:        "rate limit exceeded",
+			method:      stdhttp.MethodPost,
+			apiKey:      "abc123",
+			allow:       false,
+			wantStatus:  stdhttp.StatusTooManyRequests,
+			wantAllowed: false,
+		},
+		{
+			name:       "missing API key",
+			method:     stdhttp.MethodPost,
+			apiKey:     "",
+			wantStatus: stdhttp.StatusBadRequest,
+		},
+		{
+			name:       "wrong method",
+			method:     stdhttp.MethodGet,
+			apiKey:     "abc123",
+			wantStatus: stdhttp.StatusMethodNotAllowed,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			mock := &mockLimiter{allow: tt.allow}
+			router := handler.NewRouter(mock)
+
+			req := httptest.NewRequest(tt.method, "/check", bytes.NewReader([]byte{}))
+			if tt.apiKey != "" {
+				req.Header.Set("X-API-Key", tt.apiKey)
+			}
+
+			rr := httptest.NewRecorder()
+			router.ServeHTTP(rr, req)
+
+			if rr.Code != tt.wantStatus {
+				t.Errorf("status code = %v, want %v", rr.Code, tt.wantStatus)
+			}
+
+			// Only decode JSON for POST requests with API key
+			if tt.method == stdhttp.MethodPost && tt.apiKey != "" {
+				var body map[string]any
+				if err := json.NewDecoder(rr.Body).Decode(&body); err != nil {
+					t.Fatalf("failed to decode response: %v", err)
+				}
+				if body["allowed"] != tt.wantAllowed {
+					t.Errorf("allowed = %v, want %v", body["allowed"], tt.wantAllowed)
+				}
+				if body["api_key"] != tt.apiKey {
+					t.Errorf("api_key = %v, want %v", body["api_key"], tt.apiKey)
+				}
+			}
+		})
+	}
+}
+
+func TestMetricsEndpoint(t *testing.T) {
+	mock := &mockLimiter{allow: true}
+	router := handler.NewRouter(mock)
+
+	req := httptest.NewRequest(stdhttp.MethodGet, "/metrics", nil)
+	rr := httptest.NewRecorder()
+	router.ServeHTTP(rr, req)
+
+	if rr.Code != stdhttp.StatusOK {
+		t.Errorf("/metrics status code = %v, want %v", rr.Code, stdhttp.StatusOK)
+	}
+	if rr.Body.Len() == 0 {
+		t.Error("/metrics returned empty body")
+	}
+}