Moves unittests to root folder and adds github action to run unit tests. (#72)

* Move unit tests to root package.

* Adds deps to "test" extra, and mark two broken tests in tests/unittests/auth/test_auth_handler.py

* Adds github workflow

* minor fix in lite_llm.py for python 3.9.

* format pyproject.toml

tests/unittests/flows/llm_flows/test_identity.py

@@ -0,0 +1,66 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from google.adk.agents import Agent
+from google.adk.flows.llm_flows import identity
+from google.adk.models import LlmRequest
+from google.genai import types
+import pytest
+
+from ... import utils
+
+
+@pytest.mark.asyncio
+async def test_no_description():
+  request = LlmRequest(
+      model="gemini-1.5-flash",
+      config=types.GenerateContentConfig(system_instruction=""),
+  )
+  agent = Agent(model="gemini-1.5-flash", name="agent")
+  invocation_context = utils.create_invocation_context(agent=agent)
+
+  async for _ in identity.request_processor.run_async(
+      invocation_context,
+      request,
+  ):
+    pass
+
+  assert request.config.system_instruction == (
+      """You are an agent. Your internal name is "agent"."""
+  )
+
+
+@pytest.mark.asyncio
+async def test_with_description():
+  request = LlmRequest(
+      model="gemini-1.5-flash",
+      config=types.GenerateContentConfig(system_instruction=""),
+  )
+  agent = Agent(
+      model="gemini-1.5-flash",
+      name="agent",
+      description="test description",
+  )
+  invocation_context = utils.create_invocation_context(agent=agent)
+
+  async for _ in identity.request_processor.run_async(
+      invocation_context,
+      request,
+  ):
+    pass
+
+  assert request.config.system_instruction == "\n\n".join([
+      'You are an agent. Your internal name is "agent".',
+      ' The description about you is "test description"',
+  ])