chore: Handle invalid language in HelloHandler

internal/httpserver/handler_hello.go

@@ -21,7 +21,7 @@ func HelloHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if _, ok := msgs[lang]; !ok {
-		WriteJSON(w, http.StatusBadRequest, ErrorResponse{Error: "invalid language"})
+		WriteBadRequest(w, "invalid language")
 		return
 	}
 

internal/httpserver/handler_hello_test.go

@@ -49,4 +49,23 @@ func TestHelloHandler(t *testing.T) {
 			t.Fatalf("expected message %s, got %s", "Olá", hello.Message)
 		}
 	})
+
+	t.Run("Should return error response with invalid language", func(t *testing.T) {
+		resp, err := http.Get(srv.URL + "?lang=invalid")
+		if err != nil {
+			t.Fatalf("expected no error, got %v", err)
+		}
+
+		if resp.StatusCode != http.StatusBadRequest {
+			t.Fatalf("expected status code %d, got %d", http.StatusBadRequest, resp.StatusCode)
+		}
+		defer resp.Body.Close()
+
+		var errResp httpserver.ErrorResponse
+		json.NewDecoder(resp.Body).Decode(&errResp)
+
+		if errResp.Error != "invalid language" {
+			t.Fatalf("expected error message %s, got %s", "invalid language", errResp.Error)
+		}
+	})
 }