# `Supertester.TestableGenServer`
[🔗](https://github.com/nshkrdotcom/supertester/blob/v0.6.0/lib/supertester/testable_genserver.ex#L1)

A behavior that makes GenServers testable with Supertester.

This module injects a `__supertester_sync__` handler that allows tests to
synchronize with the GenServer without using `Process.sleep/1`.

## Usage

    defmodule MyServer do
      use GenServer
      use Supertester.TestableGenServer

      # Your GenServer implementation
    end

## Synchronization

The injected handler responds to two message formats:

- `:__supertester_sync__` - Returns `:ok` after processing
- `{:__supertester_sync__, return_state: true}` - Returns `{:ok, state}`

## Example

    {:ok, server} = MyServer.start_link()
    GenServer.cast(server, :some_operation)

    # Ensure cast is processed before continuing
    GenServer.call(server, :__supertester_sync__)

    # Now safe to verify results
    state = :sys.get_state(server)

---

*Consult [api-reference.md](api-reference.md) for complete listing*