fix: modify trailing middleware and also added test cases

internal/middleware/trailing_slash_test.go

@@ -0,0 +1,72 @@
+package middleware_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"server/internal/middleware"
+	"testing"
+)
+
+// demo test case
+// {
+// 	name: string
+// requestURL: string,
+// expectedCode: int,
+// expectedLocation
+// }
+
+func TestTrailingSlashMiddleware(t *testing.T) {
+
+	handler := middleware.TrailingSlashMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+
+	tests := []struct {
+		name         string
+		requestURL   string
+		expectedCode int
+		expectedUrl  string
+	}{
+		{
+			name:         "url with trailing slash",
+			requestURL:   "/example/",
+			expectedCode: http.StatusMovedPermanently,
+			expectedUrl:  "/example",
+		},
+		{
+			name:         "url without trailing slash",
+			requestURL:   "/example",
+			expectedCode: http.StatusOK,
+			expectedUrl:  "",
+		},
+		{
+			name:         "root url with trailing slash",
+			requestURL:   "/",
+			expectedCode: http.StatusOK,
+			expectedUrl:  "",
+		},
+		{
+			name:         "URL with Query Parameters",
+			requestURL:   "/example?query=1",
+			expectedCode: http.StatusOK,
+			expectedUrl:  "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := httptest.NewRequest("GET", tt.requestURL, nil)
+			w := httptest.NewRecorder()
+
+			handler.ServeHTTP(w, req)
+
+			if w.Code != tt.expectedCode {
+				t.Errorf("expected status %d, got %d", tt.expectedCode, w.Code)
+			}
+
+			if tt.expectedUrl != "" && w.Header().Get("Location") != tt.expectedUrl {
+				t.Errorf("expected location %s, got %s", tt.expectedUrl, w.Header().Get("Location"))
+			}
+		})
+	}
+}

internal/middleware/trailingslash.go

@@ -5,19 +5,19 @@ import (
 	"strings"
 )
 
-// TrailingSlashMiddleware is a middleware function that removes the trailing slash from the URL path.
 func TrailingSlashMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		// Check if the URL path ends with a slash and is not the root path ("/")
 		if r.URL.Path != "/" && strings.HasSuffix(r.URL.Path, "/") {
-			// Remove the trailing slash
-			r.URL.Path = strings.TrimSuffix(r.URL.Path, "/")
-			// Redirect to the new path (optional, for SEO)
-			http.Redirect(w, r, r.URL.Path, http.StatusMovedPermanently)
+			// remove slash
+			newPath := strings.TrimSuffix(r.URL.Path, "/")
+			// if query params exist append them
+			newURL := newPath
+			if r.URL.RawQuery != "" {
+				newURL += "?" + r.URL.RawQuery
+			}
+			http.Redirect(w, r, newURL, http.StatusMovedPermanently)
 			return
 		}
-
-		// Call the next handler
 		next.ServeHTTP(w, r)
 	})
 }