Nest Labs Fault Injection

Introduction

Nest Labs Fault Injection (nlfaultinjection) is designed to provide a simple, portable fault injection framework.

It should be capable of running on just about any system, no matter how constrained and depends only on the C Standard Library.

This is a simple framework that helps implement fault injection APIs. Fault injection APIs simplify the testing (manual or automated) of the error handling logic of individual components and whole systems; as a testing tool, a fault injection API is not as powerful as an extensive set of mock objects, but has the advantage of being able to run on a live system.

This is not an official Google product.

Getting Started

A SW module implements a fault-injection API by doing the following:

1. Instantiate a FaultInjection::Manager object and define a list fault IDs; the Manager needs a name, storage for the configuration of the faults and the name of each fault; the Manager instance is the public API, through which another module of the system can configure faults (for example a test harness can turn on a fault by calling the FailAtFault() method). The module should also provide a public function that returns a C++ reference to the Manager and initializes the Manager the first time it is called.
2. At the location in which the fault is to be injected, the nlFAULT_INJECT macro is used to inline code that if executed triggers a fault in the system; the macro queries the Manager object calling the CheckFault() method and executes the extra code if it returns true. The invocations of CheckFault are counted per faultID, which allows a test harness to automatically loop over different valid configurations.