[mypy] Enable type checking for test directory (#5017)

tests/lora/test_phi.py

@@ -1,3 +1,5 @@
+from typing import List
+
 import vllm
 from vllm.lora.request import LoRARequest
 
@@ -6,7 +8,7 @@ MODEL_PATH = "microsoft/phi-2"
 PROMPT_TEMPLATE = "### Instruct: {sql_prompt}\n\n### Context: {context}\n\n### Output:"  # noqa: E501
 
 
-def do_sample(llm, lora_path: str, lora_id: int) -> str:
+def do_sample(llm: vllm.LLM, lora_path: str, lora_id: int) -> List[str]:
     prompts = [
         PROMPT_TEMPLATE.format(
             sql_prompt=
@@ -35,7 +37,7 @@ def do_sample(llm, lora_path: str, lora_id: int) -> str:
         if lora_id else None,
     )
     # Print the outputs.
-    generated_texts = []
+    generated_texts: List[str] = []
     for output in outputs:
         prompt = output.prompt
         generated_text = output.outputs[0].text.strip()