code: def test_with_no_valid_pairs(self):
      loss_funcA = ContrastiveLoss()
      loss_funcB = ContrastiveLoss(distance=CosineSimilarity())
      for dtype in TEST_DTYPES:
          embedding_angles = [0]
          embeddings = torch.tensor(
              [
                  testing_utils.angle_to_coord(a)
                  for a in embedding_angles
              ],
              requires_grad=True,
              dtype=dtype,
          ).to(
              TEST_DEVICE
          )  # 2D embeddings
          labels = torch.LongTensor([0])
          lossA = loss_funcA(embeddings, labels)
          lossB = loss_funcB(embeddings, labels)
          self.assertEqual(lossA, 0)
          self.assertEqual(lossB, 0)
  
file_path: pytorch-metric-learning/tests/losses/test_contrastive_loss.py
imports: import unittest
  import torch
  from pytorch_metric_learning.distances import CosineSimilarity, LpDistance
  from pytorch_metric_learning.losses import ContrastiveLoss
  from pytorch_metric_learning.reducers import MeanReducer
  from ..None import TEST_DEVICE, TEST_DTYPES, WITH_COLLECT_STATS
  from ..zzz_testing_utils import testing_utils
label_desc: Use image node_id 2 for calling the TestContrastiveLoss obj's underlying member method code with example usage: obj.test_with_no_valid_pairs() without return types