VirtualTimeGenStateMachine

Author: d-led

README.md

@@ -66,6 +66,52 @@ test "100 seconds completes instantly" do
 end
 ```
 
+### Test state machines with virtual time
+
+```elixir
+defmodule SwitchStateMachine do
+  use VirtualTimeGenStateMachine, callback_mode: :handle_event_function
+
+  def start_link(opts) do
+    GenStateMachine.start_link(__MODULE__, :off, opts)
+  end
+
+  def init(_) do
+    {:ok, :off, %{flip_count: 0}}
+  end
+
+  def handle_event(:cast, :flip, :off, data) do
+    # Schedule timeout for 100ms
+    VirtualTimeGenStateMachine.send_after(self(), :timeout, 100)
+    {:next_state, :on, %{data | flip_count: data.flip_count + 1}}
+  end
+
+  def handle_event(:cast, :flip, :on, data) do
+    {:next_state, :off, data}
+  end
+
+  def handle_event(:info, :timeout, state, data) do
+    {:keep_state, %{data | timeout_fired: true}}
+  end
+end
+
+test "state machine transitions and timers" do
+  {:ok, clock} = VirtualClock.start_link()
+  VirtualTimeGenStateMachine.set_virtual_clock(clock)
+
+  {:ok, sm} = SwitchStateMachine.start_link([])
+  
+  # Trigger transition and schedule timeout
+  GenStateMachine.cast(sm, :flip)
+  
+  # Advance virtual time - timeout fires instantly
+  VirtualClock.advance(clock, 100)  # ~10ms real time ⚡
+  
+  # Check timeout fired
+  assert get_state(sm).timeout_fired == true
+end
+```
+
 ### Simulate message-passing systems
 
 ```elixir
@@ -277,6 +323,12 @@ end
 - All standard callbacks: `handle_call`, `handle_cast`, `handle_info`
 - Fast: simulate hours in seconds
 
+**VirtualTimeGenStateMachine** - Test state machines with virtual time
+
+- Drop-in replacement: `use VirtualTimeGenStateMachine` instead of `use GenStateMachine`
+- All standard callbacks: `handle_event`, state transitions, timeouts
+- Fast: simulate complex state transitions instantly
+
 **Actor Simulation DSL** - Prototype distributed systems
 
 - Pattern matching: declarative message handlers
@@ -310,6 +362,11 @@ use VirtualTimeGenServer
 VirtualTimeGenServer.set_virtual_clock(clock)
 VirtualTimeGenServer.send_after(pid, msg, delay)
 
+# Virtual Time GenStateMachine
+use VirtualTimeGenStateMachine, callback_mode: :handle_event_function
+VirtualTimeGenStateMachine.set_virtual_clock(clock)
+VirtualTimeGenStateMachine.send_after(pid, msg, delay)
+
 # Actor Simulation (import for clean DSL)
 import ActorSimulation
 

lib/actor_simulation/omnetpp_generator.ex

@@ -438,6 +438,7 @@ defmodule ActorSimulation.OMNeTPPGenerator do
       # Use modern CMake targets if available
       target_link_libraries(#{network_name} PRIVATE
           OmnetPP::main
+          OmnetPP::cmdenv
           OmnetPP::envir
           OmnetPP::sim
       )
@@ -452,6 +453,10 @@ defmodule ActorSimulation.OMNeTPPGenerator do
           ${OMNETPP_INCLUDE_DIRS}
           ${CMAKE_CURRENT_SOURCE_DIR}
       )
+      # Ensure shared libraries are linked properly
+      target_link_options(#{network_name} PRIVATE
+          -Wl,--no-as-needed
+      )
     endif()
     """
   end

lib/virtual_time_gen_state_machine.ex

@@ -11,7 +11,7 @@ defmodule VirtualTimeGenStateMachine do
         use VirtualTimeGenStateMachine, callback_mode: :handle_event_function
 
         def start_link(opts) do
-          VirtualTimeGenStateMachine.start_link(__MODULE__, :off, opts)
+          GenStateMachine.start_link(__MODULE__, :off, opts)
         end
 
         @impl true

mix.exs

@@ -91,7 +91,7 @@ defmodule GenServerVirtualTime.MixProject do
 
   defp description do
     """
-    Virtual time extension to `GenServer` allowing testing time-based
+    Virtual time extension to `GenServer` and `GenStateMachine` allowing testing time-based
     actor systems orders of magnitude faster than in wallclock-time.
     Includes actor simulation DSL with statistics, tracing, and code generation into other
     Actor Model implementations in C++, Pony, Go, Rust, Java.
@@ -150,6 +150,7 @@ defmodule GenServerVirtualTime.MixProject do
         Core: [
           VirtualClock,
           VirtualTimeGenServer,
+          VirtualTimeGenStateMachine,
           TimeBackend,
           VirtualTimeBackend,
           RealTimeBackend

test/virtual_time_gen_state_machine_test.exs

@@ -54,7 +54,7 @@ defmodule VirtualTimeGenStateMachineTest do
   defmodule DoorSM do
     use VirtualTimeGenStateMachine, callback_mode: :state_functions
 
-    def start_link() do
+    def start_link do
       GenStateMachine.start_link(__MODULE__, nil, [])
     end
 
@@ -121,7 +121,7 @@ defmodule VirtualTimeGenStateMachineTest do
   defmodule LightSM do
     use VirtualTimeGenStateMachine, callback_mode: [:handle_event_function, :state_enter]
 
-    def start_link() do
+    def start_link do
       GenStateMachine.start_link(__MODULE__, nil, [])
     end