Weh Inspector

WehInspector is a tool add-on to help debugging WebExtensions add-ons developed with the Weh2 toolkit (available under Mozilla Public License 2.0 from https://github.com/mi-g/weh.

It provides the following capabilities:

• Trace Weh Remote Procedure Calls between the add-on background and other components: local add-on content, web pages injected content, web workers, native applications, ...
• Read and write add-on preferences
• Read add-on storage data (both HTML5 and WebExtensions storage API)

WehInspector user interface runs in a single tab. To create or select that tab, right click in a page content and pick "Weh Inspector" from the context menu. In the dropdown menu at the top left, select the Weh2-based addon to debug (if you have only one installed, it will be selected automatically).

There is one thing it is important to understand when inspecting RPC calls: WehInspector has a settings parameter, "Messages display mode", that can take one of 3 values: "synchronous on call", "synchronous on reply", "asynchronous". Let's take a common situation where the background calls a function A from a content component, this function calls B from the background and returns. This will be 4 messages: call A, call B, reply B, reply A. If the "Messages display mode" is set to "synchronous on reply" (the default), you will see 2 entries in the WehInspector interface: the call to B, then the call to A. If set to "synchronous on call": the call to A, then the call to B, and if "asynchronous", you will see 4 entries corresponding to the messages explained earlier.