code: def test_discount_factor(self):
      curve = build_cuve()
      values = self.evaluate(
          curve.discount_factor(
              interpolation_dates=[
                  (2020, 6, 16),
                  (2021, 6, 1),
                  (2025, 1, 1),
              ]
          )
      )
      np.testing.assert_allclose(
          values, [0.99999952, 0.95284594, 0.78683929], atol=1e-6
      )
  
file_path: tf-quant-finance/tf_quant_finance/experimental/pricing_platform/framework/market_data/rate_curve_test.py
imports: from absl.testing import parameterized
  import numpy
  import tensorflow.compat.v2
  import tf_quant_finance
  from tensorflow.python.framework import test_util
label_desc: Use image node_id 2 for calling the RateCurveTest obj's underlying member method code with example usage: obj.test_discount_factor() without return types