✅(pytest) fail on tests external calls

The backend tests must not try to call the real world.

src/backend/conftest.py

@@ -0,0 +1,30 @@
+"""Global fixtures for the backend tests."""
+
+import pytest
+from urllib3.connectionpool import HTTPConnectionPool
+
+
+@pytest.fixture(autouse=True)
+def no_http_requests(monkeypatch):
+    """
+    Prevents HTTP requests from being made during tests.
+    This is useful for tests that do not require actual HTTP requests
+    and helps to avoid network-related issues.
+
+    Credits: https://blog.jerrycodes.com/no-http-requests/
+    """
+
+    allowed_hosts = {"localhost"}
+    original_urlopen = HTTPConnectionPool.urlopen
+
+    def urlopen_mock(self, method, url, *args, **kwargs):
+        if self.host in allowed_hosts:
+            return original_urlopen(self, method, url, *args, **kwargs)
+
+        raise RuntimeError(
+            f"The test was about to {method} {self.scheme}://{self.host}{url}"
+        )
+
+    monkeypatch.setattr(
+        "urllib3.connectionpool.HTTPConnectionPool.urlopen", urlopen_mock
+    )