docstr: Test CoCa model.
docstr_tok: ["Test","CoCa","model","."]
code: def test_CoCa(self):
      """
      Test CoCa model.
      """
      model = nn.Sequential()
      coca = CoCa(
          dim=4,
          img_encoder=model,
          image_dim=32,
          num_tokens=10,
          unimodal_depth=6,
          multimodal_depth=6,
          dim_head=64,
          heads=8,
          caption_loss_weight=1.0,
          contrastive_loss_weight=1.0,
      )
  
      text = torch.randint(0, 10, (4, 4))
      images = torch.randn(1, 2, 32)
      logits = coca(text=text, images=images)
      self.assertTrue(logits.shape == torch.Size([4, 4, 10]))
      text_embeds, image_embeds = coca(
          text=text, images=images, return_embeddings=True
      )
      self.assertTrue(text_embeds.shape == torch.Size([4, 4]))
      self.assertTrue(image_embeds.shape == torch.Size([1, 4]))
  
imports: import unittest
  import torch
  from torch import nn
  from towhee.models.coca.coca import CoCa
label_desc: Use image node_id 1 for calling the CoCaTest obj's underlying member method code with example usage: obj.test_CoCa() without return types