code: def test_run():
      builder = PromptBuilder(template="This is a {{ variable }}")
      res = builder.run(variable="test")
      assert res == {"prompt": "This is a test"}
  
imports: import pytest
  from haystack.components.builders.prompt_builder import PromptBuilder
label_desc: Use image node_id 3 for calling a global function with example usage: test_run() without return types