feat(models): Enable multi-provider support for Claude and LiteLLM

Merges: https://github.com/google/adk-python/pull/2810

Co-authored-by: Xuan Yang <xygoogle@google.com>
PiperOrigin-RevId: 836706608

tests/unittests/models/test_models.py

@@ -15,7 +15,7 @@
 from google.adk import models
 from google.adk.models.anthropic_llm import Claude
 from google.adk.models.google_llm import Gemini
-from google.adk.models.registry import LLMRegistry
+from google.adk.models.lite_llm import LiteLlm
 import pytest
 
 
@@ -34,6 +34,7 @@ import pytest
     ],
 )
 def test_match_gemini_family(model_name):
+  """Test that Gemini models are resolved correctly."""
   assert models.LLMRegistry.resolve(model_name) is Gemini
 
 
@@ -51,12 +52,63 @@ def test_match_gemini_family(model_name):
     ],
 )
 def test_match_claude_family(model_name):
-  LLMRegistry.register(Claude)
-
+  """Test that Claude models are resolved correctly."""
   assert models.LLMRegistry.resolve(model_name) is Claude
 
 
+@pytest.mark.parametrize(
+    'model_name',
+    [
+        'openai/gpt-4o',
+        'openai/gpt-4o-mini',
+        'groq/llama3-70b-8192',
+        'groq/mixtral-8x7b-32768',
+        'anthropic/claude-3-opus-20240229',
+        'anthropic/claude-3-5-sonnet-20241022',
+    ],
+)
+def test_match_litellm_family(model_name):
+  """Test that LiteLLM models are resolved correctly."""
+  assert models.LLMRegistry.resolve(model_name) is LiteLlm
+
+
 def test_non_exist_model():
   with pytest.raises(ValueError) as e_info:
     models.LLMRegistry.resolve('non-exist-model')
   assert 'Model non-exist-model not found.' in str(e_info.value)
+
+
+def test_helpful_error_for_claude_without_extensions():
+  """Test that missing Claude models show helpful install instructions.
+
+  Note: This test may pass even when anthropic IS installed, because it
+  only checks the error message format when a model is not found.
+  """
+  # Use a non-existent Claude model variant to trigger error
+  with pytest.raises(ValueError) as e_info:
+    models.LLMRegistry.resolve('claude-nonexistent-model-xyz')
+
+  error_msg = str(e_info.value)
+  # The error should mention anthropic package and installation instructions
+  # These checks work whether or not anthropic is actually installed
+  assert 'Model claude-nonexistent-model-xyz not found' in error_msg
+  assert 'anthropic package' in error_msg
+  assert 'pip install' in error_msg
+
+
+def test_helpful_error_for_litellm_without_extensions():
+  """Test that missing LiteLLM models show helpful install instructions.
+
+  Note: This test may pass even when litellm IS installed, because it
+  only checks the error message format when a model is not found.
+  """
+  # Use a non-existent provider to trigger error
+  with pytest.raises(ValueError) as e_info:
+    models.LLMRegistry.resolve('unknown-provider/gpt-4o')
+
+  error_msg = str(e_info.value)
+  # The error should mention litellm package for provider-style models
+  assert 'Model unknown-provider/gpt-4o not found' in error_msg
+  assert 'litellm package' in error_msg
+  assert 'pip install' in error_msg
+  assert 'Provider-style models' in error_msg