docs: add testing section

Author: heitorlessa

docs/core/event_handler/api_gateway.md

@@ -651,7 +651,60 @@ Like `compress` feature, the client must send the `Accept` header with the corre
     }
     ```
 
-### Testing your code
+## Testing your code
+
+You can test your routes by passing a proxy event request where `path` and `httpMethod`.
+
+=== "test_app.py"
+
+	```python hl_lines="18-24"
+	from dataclasses import dataclass
+
+	import pytest
+	import app
+
+    @pytest.fixture
+    def lambda_context():
+		@dataclass
+		class LambdaContext:
+			function_name: str = "test"
+			memory_limit_in_mb: int = 128
+			invoked_function_arn: str = "arn:aws:lambda:eu-west-1:809313241:function:test"
+			aws_request_id: str = "52fdfc07-2182-154f-163f-5f0f9a621d72"
+
+        return LambdaContext()
+
+    def test_lambda_handler(lambda_context):
+		minimal_event = {
+			"path": "/hello",
+			"httpMethod": "GET"
+	  		"requestContext": {  # correlation ID
+				"requestId": "c6af9ac6-7b61-11e6-9a41-93e8deadbeef"
+			}
+		}
+
+        app.lambda_handler(minimal_event, lambda_context)
+	```
+
+=== "app.py"
+
+	```python
+	from aws_lambda_powertools import Logger
+	from aws_lambda_powertools.logging import correlation_paths
+	from aws_lambda_powertools.event_handler.api_gateway import ApiGatewayResolver
+
+	logger = Logger()
+	app = ApiGatewayResolver()  # by default API Gateway REST API (v1)
+
+	@app.get("/hello")
+	def get_hello_universe():
+		return {"message": "hello universe"}
+
+	# You can continue to use other utilities just as before
+	@logger.inject_lambda_context(correlation_id_path=correlation_paths.API_GATEWAY_REST)
+	def lambda_handler(event, context):
+		return app.resolve(event, context)
+	```
 
 
 ## FAQ