[GPCAPIM-275]: Harmonise the Controller, Flask entry point and Provider System modules

gateway-api/pyproject.toml

@@ -13,6 +13,7 @@ clinical-data-common = { git = "https://github.com/NHSDigital/clinical-data-comm
 flask = "^3.1.2"
 types-flask = "^1.1.6"
 requests = "^2.32.5"
+pytest-mock = "^3.15.1"
 
 [tool.poetry]
 packages = [{include = "gateway_api", from = "src"},
@@ -55,6 +56,7 @@ dev = [
     "schemathesis>=4.4.1",
     "types-requests (>=2.32.4.20250913,<3.0.0.0)",
     "types-pyyaml (>=6.0.12.20250915,<7.0.0.0)",
+    "pytest-mock (>=3.15.1,<4.0.0)",
 ]
 
 [tool.mypy]

gateway-api/src/gateway_api/conftest.py

@@ -1,6 +1,9 @@
 """Pytest configuration and shared fixtures for gateway API tests."""
 
+from datetime import datetime, timezone
+
 import pytest
+from fhir.bundle import Bundle
 from fhir.parameters import Parameters
 
 
@@ -18,3 +21,36 @@ def valid_simple_request_payload() -> Parameters:
             },
         ],
     }
+
+
+@pytest.fixture
+def valid_simple_response_payload() -> Bundle:
+    return {
+        "resourceType": "Bundle",
+        "id": "example-patient-bundle",
+        "type": "collection",
+        "timestamp": datetime.now(timezone.utc).isoformat(),
+        "entry": [
+            {
+                "fullUrl": "https://example.com/Patient/9999999999",
+                "resource": {
+                    "name": [{"family": "Alice", "given": ["Johnson"], "use": "Ally"}],
+                    "gender": "female",
+                    "birthDate": "1990-05-15",
+                    "resourceType": "Patient",
+                    "id": "9999999999",
+                    "identifier": [
+                        {"value": "9999999999", "system": "urn:nhs:numbers"}
+                    ],
+                },
+            }
+        ],
+    }
+
+
+@pytest.fixture
+def valid_headers() -> dict[str, str]:
+    return {
+        "Ssp-TraceID": "test-trace-id",
+        "ODS-from": "test-ods",
+    }