1. A system providing a web-based service, wherein interaction with back-end components is testable in a production environment, the system comprising: a first computing node that, when activated, receives requests to perform an operation on behalf of a client of the web-based service, the operation comprising one or more sub-operations; one or more additional computing nodes that, when activated, perform the sub-operations in response to a request transmitted from the first computing node; and one or more memories having stored thereon computer-executable instructions that, upon execution, cause the system at least to: receive at the first computing node a first request to perform the operation; receive a first data indicative of a test condition for the one or more additional computing nodes, the first data appended to the first request; initiate processing of the first request based at least in part on determining that a user account associated with the client is authorized to issue the request to perform the operation; intercept, during processing of the first request, an invocation of at least one of the sub-operations, the interception based at least in part on the data indicative of the test condition and further based at least in part on the user account being authorized to perform testing; and simulate a result of performing the at least one of the sub-operations on one or more additional computing nodes, the result corresponding to the test condition.