new_contents: import pytest
  
  from ..pytest_helpers import (
      _function_call_string,
      run_test_of_function,
  )
  
  
  def f(*args, **kwargs):
      return None
  
  
  # f, args, kwargs, expected
  call_string_table = [
      (f, (), {}, "f()"),
      (f, (1), {}, "f(1)"),
      (f, ('x'), {}, "f('x')"),
      (f, (1, 'b', {}), {}, "f(1, 'b', {})"),
      (f, (), {'kw': 1}, "f(kw=1)"),
      (f, (), {'x': 'c'}, "f(x='c')"),
      (f, (1, 'b'), {'b': 42, 'R2': 'D2'}, "f(1, 'b', b=42, R2='D2')"),
  ]
  
  
  @pytest.mark.parametrize("f,args,kwargs,expected", call_string_table)
  def test__function_call_string(f, args, kwargs, expected):
      """Tests that _function_call_string returns a string that is
      equivalent to the function call."""
      assert expected == _function_call_string(f, args, kwargs)
  
subject: Add tests for function to reproduce a call string