chore: Add test to server error

lib/ferrum/errors.rb

@@ -6,7 +6,8 @@ class NoSuchPageError     < Error; end
   class NoSuchTargetError   < Error; end
   class NotImplementedError < Error; end
   class BinaryNotFoundError < Error; end
-  class EmptyPathError < Error; end
+  class EmptyPathError      < Error; end
+  class ServerError         < Error; end
 
   class StatusError < Error
     def initialize(url, message = nil)

spec/page_spec.rb

@@ -40,6 +40,14 @@
           )
         end
       end
+
+      it "handles server error" do
+        expect { page.go_to("/ferrum/server_error") }.not_to raise_error
+
+        expect(page.network.status).to eq(500)
+        expect(page.network.traffic.last.error.description)
+          .to eq("Failed to load resource: the server responded with a status of 500 (Internal Server Error)")
+      end
     end
   end
 

spec/support/application.rb

@@ -241,7 +241,7 @@ def requires_credentials(login, password)
         return if authorized?(login, password)
 
         headers["WWW-Authenticate"] = %(Basic realm="Restricted Area")
-        halt 401, "Not authorized\n"
+        halt(401, "Not authorized\n")
       end
 
       def authorized?(login, password)
@@ -271,7 +271,11 @@ def authorized?(login, password)
     end
 
     get "/ferrum/unexist.png" do
-      halt 404
+      halt(404)
+    end
+
+    get "/ferrum/server_error" do
+      halt(500)
     end
 
     get "/ferrum/status/:status" do
@@ -329,7 +333,7 @@ def authorized?(login, password)
     post "/ferrum/ping" do
       # Sleeping to simulate a server that does not send a response to PING requests
       sleep 5
-      halt 204
+      halt(204)
     end
 
     protected