Added file upload support

backends/mizan-fastapi/tests/test_upload.py

@@ -0,0 +1,71 @@
+"""Upload dispatch over FastAPI multipart — files bind into Upload fields and
+the declarative `File(...)` constraints are enforced."""
+
+from __future__ import annotations
+
+import json
+from typing import Annotated
+
+import pytest
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+from pydantic import BaseModel
+
+from mizan_core.client.function import client
+from mizan_core.registry import clear_registry, register
+from mizan_fastapi import File, MizanError, Upload, mizan_exception_handler, router as mizan_router
+
+
+class AvatarOut(BaseModel):
+    ok: bool
+    size: int
+    name: str | None = None
+
+
+@pytest.fixture
+def app():
+    clear_registry()
+
+    @client
+    def set_avatar(
+        request,
+        user_id: int,
+        avatar: Annotated[Upload, File(max_size="1MB", content_types=["image/png"])],
+    ) -> AvatarOut:
+        return AvatarOut(ok=True, size=avatar.size, name=avatar.filename)
+
+    register(set_avatar, "set_avatar")
+
+    fastapi_app = FastAPI()
+    fastapi_app.include_router(mizan_router, prefix="/api/mizan")
+    fastapi_app.add_exception_handler(MizanError, mizan_exception_handler)
+    return fastapi_app
+
+
+def _post(test_client: TestClient, args: dict, file_tuple: tuple):
+    return test_client.post(
+        "/api/mizan/call/",
+        data={"fn": "set_avatar", "args": json.dumps(args)},
+        files={"avatar": file_tuple},
+    )
+
+
+def test_upload_binds_and_executes(app):
+    resp = _post(TestClient(app), {"user_id": 5}, ("a.png", b"\x89PNG" + b"x" * 100, "image/png"))
+    assert resp.status_code == 200, resp.text
+    result = resp.json()["result"]
+    assert result["ok"] is True
+    assert result["name"] == "a.png"
+    assert result["size"] == 104
+
+
+def test_max_size_rejected(app):
+    resp = _post(TestClient(app), {"user_id": 5}, ("b.png", b"x" * (2 * 1024 * 1024), "image/png"))
+    assert resp.status_code == 400
+    assert "max size" in resp.text
+
+
+def test_content_type_rejected(app):
+    resp = _post(TestClient(app), {"user_id": 5}, ("c.gif", b"GIF89a", "image/gif"))
+    assert resp.status_code == 400
+    assert "content-type" in resp.text