Bluetooth test interfaces

The Pandora Bluetooth test interfaces are Remote Procedure Call (RPC) interfaces exposed to testing tools to trigger behaviors within a Bluetooth stack under test.

While all Bluetooth stacks are different in their supported profiles, features, and corresponding APIs, the goal of Pandora is to provide a set of unified test interfaces which they could all implement, so we can reuse and scale testing tools and processes across all of them.

Requirements

Since each Bluetooth stack exposes different APIs, the test interfaces must be generic enough and must not rely on any implementation specific behavior. However, they must ensure that they provide all the necessary access to the existing testing tools. For this reason, the test interfaces are co-designed by multiple teams at Google.

The test interfaces must be implemented using gRPC services and must use protocol buffers as Interface Definition Language (IDL). A Bluetooth stack under test exposing such interfaces must thus implement a gRPC server.

The test interfaces definition must follow the Pandora style guide.

Abstraction level

A test interface is defined for each Bluetooth profile (standard or custom). This allows the Bluetooth stack under test to implement only the test interfaces corresponding to its supported profiles. Additional platform/device-specific interfaces may also be added if necessary (but should be avoided as much as possible).

The same test interface can be implemented at different levels: for instance, in Android, the Pandora Bluetooth test interfaces can be implemented both on top of Topshim (which is a Rust shim layer just on top of the stack), which is advantageous as tests running at that level can apply to Chrome OS as well, or on top of the Android Bluetooth SDK (Java) which is advantageous for Mainline, since the Bluetooth module includes both the stack and the SDK.

Optional features

As Bluetooth profiles contain optional features, some methods of the test interfaces might not be implementable by a specific Bluetooth stack.

Such unimplemented methods must return an UNIMPLEMENTED status code as defined by gRPC.

Discovering which features are supported by a Bluetooth stack is not (yet) part of the test interfaces as this is already doable via Bluetooth SIG Implementation Conformance Statements (ICS).