What is the best practice for testing a service before the external API is available?

The preferred approach in this scenario is to create a service and implement the mockFull callback while setting the service mode to mock. This method allows developers to simulate the responses of the external API without actually making calls to it, which is particularly useful when the external API is not yet available.

By utilizing the mockFull callback, developers can define the specific responses that the service should return when certain requests are made. This flexibility allows comprehensive testing of how the application handles different scenarios, including successful responses, errors, and edge cases.

Setting the service mode to mock ensures that all interactions with the service will utilize the mocked responses, allowing for a focused testing environment. This is especially critical in development phases where the actual backend services might be in flux or under development, as it prevents dependency on the availability and stability of external systems.

Incorporating this method facilitates the creation of robust test cases without requiring access to a potentially unstable external API, ultimately resulting in smoother development and integration processes.