fix(event-handler): swagger schema respects api stage (#3796)

aws_lambda_powertools/event_handler/api_gateway.py

@@ -1692,7 +1692,13 @@ def swagger_handler():
                     body=escaped_spec,
                 )
 
-            body = generate_swagger_html(escaped_spec, path, swagger_js, swagger_css, swagger_base_url)
+            body = generate_swagger_html(
+                escaped_spec,
+                f"{base_path}{path}",
+                swagger_js,
+                swagger_css,
+                swagger_base_url,
+            )
 
             return Response(
                 status_code=200,

tests/functional/event_handler/test_openapi_swagger.py

@@ -73,3 +73,30 @@ def test_openapi_swagger_json_view_with_custom_path():
     assert result["multiValueHeaders"]["Content-Type"] == ["application/json"]
     assert isinstance(json.loads(result["body"]), Dict)
     assert "OpenAPI JSON View" in result["body"]
+
+
+def test_openapi_swagger_with_rest_api_default_stage():
+    app = APIGatewayRestResolver(enable_validation=True)
+    app.enable_swagger()
+
+    event = load_event("apiGatewayProxyEvent.json")
+    event["path"] = "/swagger"
+    event["requestContext"]["stage"] = "$default"
+
+    result = app(event, {})
+    assert result["statusCode"] == 200
+    assert "ui.specActions.updateUrl('/swagger?format=json')" in result["body"]
+
+
+def test_openapi_swagger_with_rest_api_stage():
+    app = APIGatewayRestResolver(enable_validation=True)
+    app.enable_swagger()
+
+    event = load_event("apiGatewayProxyEvent.json")
+    event["path"] = "/swagger"
+    event["requestContext"]["stage"] = "prod"
+    event["requestContext"]["path"] = "/prod/swagger"
+
+    result = app(event, {})
+    assert result["statusCode"] == 200
+    assert "ui.specActions.updateUrl('/prod/swagger?format=json')" in result["body"]