[BUG] Inconsistent HTTP status code on query mismatch (#712)

The logical behavior of a router should return an HTTP status code of
404 when a request fails to satisfy route validation logic. Previously,
MUX was returning a 405 HTTP status code in some rare scenarios, which
was not valid in its case.

For more info, See: #704

Fixes #704 

**Summary of Changes**

1. Clear the mismatch error of the previous validations on method match.
2. Added related tests

> PS: Make sure your PR includes/updates tests! If you need help with
this part, just ask!

Co-authored-by: Corey Daley <[email protected]>

Author: soheilrt

mux_test.go

@@ -2069,6 +2069,53 @@ func TestNoMatchMethodErrorHandler(t *testing.T) {
 	}
 }
 
+func TestMultipleDefinitionOfSamePathWithDifferentMethods(t *testing.T) {
+	emptyHandler := func(w http.ResponseWriter, r *http.Request) {}
+
+	r := NewRouter()
+	r.HandleFunc("/api", emptyHandler).Methods("POST")
+	r.HandleFunc("/api", emptyHandler).Queries("time", "{time:[0-9]+}").Methods("GET")
+
+	t.Run("Post Method should be matched properly", func(t *testing.T) {
+		req, _ := http.NewRequest("POST", "http://localhost/api", nil)
+		match := new(RouteMatch)
+		matched := r.Match(req, match)
+		if !matched {
+			t.Error("Should have matched route for methods")
+		}
+		if match.MatchErr != nil {
+			t.Error("Should not have any matching error. Found:", match.MatchErr)
+		}
+	})
+
+	t.Run("Get Method with invalid query value should not match", func(t *testing.T) {
+		req, _ := http.NewRequest("GET", "http://localhost/api?time=-4", nil)
+		match := new(RouteMatch)
+		matched := r.Match(req, match)
+		if matched {
+			t.Error("Should not have matched route for methods")
+		}
+		if match.MatchErr != ErrNotFound {
+			t.Error("Should have ErrNotFound error. Found:", match.MatchErr)
+		}
+	})
+
+	t.Run("A mismach method of a valid path should return ErrMethodMismatch", func(t *testing.T) {
+		r := NewRouter()
+		r.HandleFunc("/api2", emptyHandler).Methods("POST")
+		req, _ := http.NewRequest("GET", "http://localhost/api2", nil)
+		match := new(RouteMatch)
+		matched := r.Match(req, match)
+		if matched {
+			t.Error("Should not have matched route for methods")
+		}
+		if match.MatchErr != ErrMethodMismatch {
+			t.Error("Should have ErrMethodMismatch error. Found:", match.MatchErr)
+		}
+	})
+
+}
+
 func TestErrMatchNotFound(t *testing.T) {
 	emptyHandler := func(w http.ResponseWriter, r *http.Request) {}
 

route.go

@@ -66,6 +66,16 @@ func (r *Route) Match(req *http.Request, match *RouteMatch) bool {
 
 			matchErr = nil // nolint:ineffassign
 			return false
+		} else {
+			// Multiple routes may share the same path but use different HTTP methods. For instance:
+			// Route 1: POST "/users/{id}".
+			// Route 2: GET "/users/{id}", parameters: "id": "[0-9]+".
+			//
+			// The router must handle these cases correctly. For a GET request to "/users/abc" with "id" as "-2",
+			// The router should return a "Not Found" error as no route fully matches this request.
+			if match.MatchErr == ErrMethodMismatch {
+				match.MatchErr = nil
+			}
 		}
 	}