fix: variable name in undefined variable exceptin message

Author: Cervajz

lib/solid/undefined_variable_error.ex

@@ -4,8 +4,17 @@ defmodule Solid.UndefinedVariableError do
 
   @impl true
   def message(exception) do
+    variable = exception.variable
+
+    variable_name =
+      if is_list(variable) do
+        Enum.join(variable, ".")
+      else
+        variable
+      end
+
     line = exception.loc.line
-    reason = "Undefined variable #{exception.variable}"
+    reason = "Undefined variable #{variable_name}"
     "#{line}: #{reason}"
   end
 end

test/solid_test.exs

@@ -268,5 +268,26 @@ defmodule SolidTest do
                }
              ]
     end
+
+    test "undefined variable error message with multiple variables" do
+      template = "{{ var1 }}\n{{ event.name }}\n{{ user.properties.name }}"
+
+      {:error, [first_error, second_error, third_error], _partial_result} =
+        template
+        |> Solid.parse!()
+        |> Solid.render(%{}, strict_variables: true, file_system: {TestFileSystem, nil})
+
+      assert String.contains?(Solid.UndefinedVariableError.message(first_error), "var1")
+
+      assert String.contains?(
+               Solid.UndefinedVariableError.message(second_error),
+               "event.name"
+             )
+
+      assert String.contains?(
+               Solid.UndefinedVariableError.message(third_error),
+               "user.properties.name"
+             )
+    end
   end
 end