add config and docs for limits

tests/test_request.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+from flask import Flask
+from flask import Request
+from flask import request
+from flask.testing import FlaskClient
+
+
+def test_max_content_length(app: Flask, client: FlaskClient) -> None:
+    app.config["MAX_CONTENT_LENGTH"] = 50
+
+    @app.post("/")
+    def index():
+        request.form["myfile"]
+        AssertionError()
+
+    @app.errorhandler(413)
+    def catcher(error):
+        return "42"
+
+    rv = client.post("/", data={"myfile": "foo" * 50})
+    assert rv.data == b"42"
+
+
+def test_limit_config(app: Flask):
+    app.config["MAX_CONTENT_LENGTH"] = 100
+    app.config["MAX_FORM_MEMORY_SIZE"] = 50
+    app.config["MAX_FORM_PARTS"] = 3
+    r = Request({})
+
+    # no app context, use Werkzeug defaults
+    assert r.max_content_length is None
+    assert r.max_form_memory_size == 500_000
+    assert r.max_form_parts == 1_000
+
+    # in app context, use config
+    with app.app_context():
+        assert r.max_content_length == 100
+        assert r.max_form_memory_size == 50
+        assert r.max_form_parts == 3
+
+    # regardless of app context, use override
+    r.max_content_length = 90
+    r.max_form_memory_size = 30
+    r.max_form_parts = 4
+
+    assert r.max_content_length == 90
+    assert r.max_form_memory_size == 30
+    assert r.max_form_parts == 4
+
+    with app.app_context():
+        assert r.max_content_length == 90
+        assert r.max_form_memory_size == 30
+        assert r.max_form_parts == 4