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Istio Test Framework Developer Guide

This document describes the overall architecture of the Istio test framework and describes how to extend its capabilities.

Overview

At a high-level, the framework is simple:

Istio test framework overview

The Runtime creates the Context, which is the main API to the test code. The Runtime chooses the appropriate component Registry based on the flags and then provides it to the Context. When the test Requires components, the Context looks them up in the Registry, which provides factories for the components.

Extending the Framework

Adding a API

To add a new component API:

  1. Add the Go file for the interface to api/components, along with a GetXXX function for extracting that component from the context.
  2. Add an ID for the component to ids.go.
  3. Add a Descriptor for the component to descriptors.go.
    • If a single environment can support multiple versions of a component (e.g. real vs fake), specify the Variant to distinguish between the two.
    • At a minimum, the descriptor should require ids.Environment.

Adding a Component

Once you have a component API, you can add an implementation as follows:

  1. Create the directory runtime/components/<component_name> which will hold the implementation.
  2. Under that directory, write a Go class implementing the component API and write a factory method for constructing it.
  3. Register your component with one of the environment registries defined in registries.go.

Adding an Environment

Environments are just slightly specialized components, so the process for adding an environment is similar. The interface for Environment is part of the runtime and is located at [runtime/api/environment.go].

To add a new environment, follow these steps:

  1. Create the directory runtime/components/environment/<environment> which will hold the implementation.
  2. Under that directory, write a Go class implementing the Environment API and write a factory method for constructing it.
  3. In registries.go add a new variable for the environment. For example: MyEnv = newEnvironment(descriptors.MyEnvironment, myenv.NewEnvironment).
  4. In registries.go register any components with the new environment.