From 53f338000f222a8e00497b407a6b619ce5c26950 Mon Sep 17 00:00:00 2001
From: David Khourshid <davidkpiano@gmail.com>
Date: Fri, 4 Oct 2019 13:23:38 -0400
Subject: [PATCH] feat(@xstate/fsm): execute actions

---
 packages/xstate-fsm/README.md        |  2 ++
 packages/xstate-fsm/src/index.ts     | 13 +++++++++---
 packages/xstate-fsm/test/fsm.test.ts | 31 ++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/packages/xstate-fsm/README.md b/packages/xstate-fsm/README.md
index 75a709d709..c8c89cffbb 100644
--- a/packages/xstate-fsm/README.md
+++ b/packages/xstate-fsm/README.md
@@ -213,6 +213,8 @@ An object that represents the state of a machine with the following schema:
 
 Creates an instance of an interpreted machine, also known as a **service**. This is a stateful representation of the running machine, which you can subscribe to, send events to, start, and stop.
 
+Actions will also be executed by the interpreter.
+
 | Argument  | Type         | Description                    |
 | --------- | ------------ | ------------------------------ |
 | `machine` | StateMachine | The machine to be interpreted. |
diff --git a/packages/xstate-fsm/src/index.ts b/packages/xstate-fsm/src/index.ts
index 3901f79d3f..0924e13c65 100644
--- a/packages/xstate-fsm/src/index.ts
+++ b/packages/xstate-fsm/src/index.ts
@@ -36,6 +36,12 @@ function createMatcher(value) {
   return stateValue => value === stateValue;
 }
 
+function toEventObject<TEvent extends EventObject>(
+  event: TEvent['type'] | TEvent
+): TEvent {
+  return (typeof event === 'string' ? { type: event } : event) as TEvent;
+}
+
 export function createMachine<
   TContext extends object,
   TEvent extends EventObject = EventObject,
@@ -60,9 +66,7 @@ export function createMachine<
         typeof state === 'string'
           ? { value: state, context: fsmConfig.context! }
           : state;
-      const eventObject = (typeof event === 'string'
-        ? { type: event }
-        : event) as TEvent;
+      const eventObject = toEventObject(event);
       const stateConfig = fsmConfig.states[value];
 
       if (!IS_PRODUCTION) {
@@ -167,6 +171,9 @@ export function interpret<
         return;
       }
       state = machine.transition(state, event);
+      state.actions.forEach(
+        ({ exec }) => exec && exec(state.context, toEventObject(event))
+      );
       listeners.forEach(listener => listener(state));
     },
     subscribe: (listener: StateMachine.StateListener<typeof state>) => {
diff --git a/packages/xstate-fsm/test/fsm.test.ts b/packages/xstate-fsm/test/fsm.test.ts
index 8810932dac..ecc2c7bfc4 100644
--- a/packages/xstate-fsm/test/fsm.test.ts
+++ b/packages/xstate-fsm/test/fsm.test.ts
@@ -176,4 +176,35 @@ describe('interpreter', () => {
 
     toggleService.send('TOGGLE');
   });
+
+  it('should execute actions', done => {
+    let executed = false;
+
+    const actionMachine = createMachine({
+      initial: 'active',
+      states: {
+        active: {
+          on: {
+            TOGGLE: {
+              target: 'inactive',
+              actions: () => {
+                executed = true;
+              }
+            }
+          }
+        },
+        inactive: {}
+      }
+    });
+
+    const actionService = interpret(actionMachine).start();
+
+    actionService.subscribe(() => {
+      if (executed) {
+        done();
+      }
+    });
+
+    actionService.send('TOGGLE');
+  });
 });