'Test the case sensitivity flag and corresponding behavior'

def test_variable_case_sensitivity(self):

    self.assertEqual(calc.evaluator({'R1': 2.0, 'R3': 4.0}, {}, 'r1*r3'), 8.0)
    variables = {'t': 1.0}
    self.assertEqual(calc.evaluator(variables, {}, 't'), 1.0)
    self.assertEqual(calc.evaluator(variables, {}, 'T'), 1.0)
    self.assertEqual(calc.evaluator(variables, {}, 't', case_sensitive=True), 1.0)
    self.assertAlmostEqual(calc.evaluator(variables, {}, 'T', case_sensitive=True), 298, delta=0.2)
