ci: add deployment workflow and automated tests

main.py

@@ -1,6 +1,8 @@
+from typing import Self
+
 from fastapi import FastAPI, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
-from pydantic import BaseModel
+from pydantic import BaseModel, Field, field_validator, model_validator
 from sqlalchemy import select
 from sqlalchemy.exc import SQLAlchemyError
 
@@ -18,13 +20,43 @@ app.add_middleware(
 
 
 class todocreate(BaseModel):
-    task: str
+    task: str = Field(min_length=1, max_length=200)
 
+    @field_validator("task")
+    @classmethod
+    def task_must_not_be_blank(cls, value: str) -> str:
+        if not value.strip():
+            raise ValueError("task must not be blank")
+
+        return value
 
 class todoupdate(BaseModel):
     completion: bool | None = None
-    task: str | None = None
+    task: str | None = Field(
+        default=None,
+        min_length=1,
+        max_length=200,
+    )
 
+    @field_validator("task")
+    @classmethod
+    def task_must_not_be_blank(
+        cls,
+        value: str | None,
+    ) -> str | None:
+        if value is not None and not value.strip():
+            raise ValueError("task must not be blank")
+
+        return value
+    
+    @model_validator(mode="after")
+    def at_least_one_field_must_be_provided(self) -> Self:
+        if self.task is None and self.completion is None:
+            raise ValueError(
+                "task or completion must be provided"
+            )
+
+        return self
 
 class todoresponse(BaseModel):
     id: int