Add tets for `Form` model with `File` field

tests/test_forms_single_model.py

@@ -1,7 +1,7 @@
 from typing import List, Optional
 
 from dirty_equals import IsDict
-from fastapi import FastAPI, Form
+from fastapi import FastAPI, File, Form
 from fastapi.testclient import TestClient
 from pydantic import BaseModel, Field
 from typing_extensions import Annotated
@@ -17,11 +17,24 @@ class FormModel(BaseModel):
     alias_with: str = Field(alias="with", default="nothing")
 
 
+class FormWithFileModel(BaseModel):
+    comment: str
+    file_data: bytes = File()
+
+
 @app.post("/form/")
 def post_form(user: Annotated[FormModel, Form()]):
     return user
 
 
+@app.post("/form-with-file/")
+def post_form_(form_data: Annotated[FormWithFileModel, Form()]):
+    return {
+        "comment": form_data.comment,
+        "file_size": len(form_data.file_data),
+    }
+
+
 client = TestClient(app)
 
 
@@ -131,3 +144,74 @@ def test_no_data():
             ]
         }
     )
+
+
+def test_form_with_file():
+    file_content = b"Hello, this is a test file."
+    response = client.post(
+        "/form-with-file/",
+        data={"comment": "This is a comment."},
+        files={"file_data": ("test.txt", file_content, "text/plain")},
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == {
+        "comment": "This is a comment.",
+        "file_size": len(file_content),
+    }
+
+
+def test_form_with_file_missing_file():
+    response = client.post(
+        "/form-with-file/",
+        data={"comment": "This is a comment."},
+    )
+    assert response.status_code == 422, response.text
+    assert response.json() == IsDict(
+        {
+            "detail": [
+                {
+                    "type": "missing",
+                    "loc": ["body", "file_data"],
+                    "msg": "Field required",
+                    "input": {"comment": "This is a comment."},
+                }
+            ]
+        }
+    ) | IsDict(
+        # TODO: remove when deprecating Pydantic v1
+        {
+            "detail": [
+                {
+                    "loc": ["body", "file_data"],
+                    "msg": "field required",
+                    "type": "value_error.missing",
+                }
+            ]
+        }
+    )
+
+
+def test_form_with_file_openapi():
+    response = client.get("/openapi.json")
+    assert response.status_code == 200, response.text
+    openapi_schema = response.json()
+    assert openapi_schema["paths"]["/form-with-file/"]["post"]["requestBody"] == {
+        "content": {
+            "multipart/form-data": {
+                "schema": {
+                    "$ref": "#/components/schemas/FormWithFileModel",
+                },
+            },
+        },
+        "required": True,
+    }
+
+    assert openapi_schema["components"]["schemas"]["FormWithFileModel"] == {
+        "title": "FormWithFileModel",
+        "type": "object",
+        "properties": {
+            "file_data": {"title": "File Data", "type": "string", "format": "binary"},
+            "comment": {"title": "Comment", "type": "string"},
+        },
+        "required": ["comment", "file_data"],
+    }