class_docstr: Test form submit button.
class_docstr_tok: ["Test","form","submit","button","."]
code: def test_return_true_when_submitted(self):
      with st.form("form"):
          submitted = st.form_submit_button("Submit")
          self.assertEqual(submitted, True)
  
imports: from unittest.mock import MagicMock, patch
  import streamlit
  from streamlit.errors import StreamlitAPIException
  from streamlit.runtime.state.session_state import RegisterWidgetResult
  from tests.delta_generator_test_case import DeltaGeneratorTestCase
label_desc: Use image node_id 10 for calling the FormSubmitButtonTest obj's underlying member method code with example usage: obj.test_return_true_when_submitted() without return types