The core of the project is an HTTP server called Scripting Layer for Fuchsia (SL4F), which runs on Fuchsia devices. The server processes JSON RPC requests from remote host driven test frameworks in the form of core service commands, parses these requests, and fulfills them with the appropriate Fuchsia equivalent (FIDL) commands.
To include SL4F by default in the build include it with your build: --with //src/testing/sl4f. Note that SL4F is only supported on *_eng products like workstation_eng. core is not supported.
Start a new SL4F component instance with ffx component start /core/sl4f.
fx build.ffx component reload /core/sl4f.Note: you can tune your test framework to open an ssh connection to run SL4F in the background.
Facades in SL4F are wrappers around FIDL APIs and maintain stateful context for successive interaction with services and enable introspection of state for making assertions. For example a facade may record asyncronous events making them available for a test to later verify.
In src/testing/sl4f/server/sl4f.rs there is a macro called with_line. Use this with your tag in your log lines.
Example:
200: let tag = "GenericFacade::func";
201: tracing::info!(tag = &with_line!(tag), "{:?}", "Really important log.");
This outputs to
GenericFacade::func:201 Really important log.