Add a little tiny bit of testing for the fsm.

js/fsm.mjs

@@ -117,8 +117,8 @@
   names in the event handler class (`VideoEvents` above).
 
  */
-import assert from "./assert.js";
-import { log } from "./logging.js";
+
+import assert from "assert";
 
 /*
   A very simple Finite State Machine class.  Nothing fancy, just a state
@@ -205,12 +205,12 @@ export class FSM {
       assert(next_state.length == 2, `Returning an array only allows 2 elements (state, func) but you returned ${next_state}`);
       let [state, func] = next_state;
 
-      log.debug(`FSM ${this.events.constructor.name}: (${event}) = ${this.state} -> ${state} (${args})`, "DATA:", this.data, func ? `THEN ${func.name}()` : undefined);
+      console.debug(`FSM ${this.events.constructor.name}: (${event}) = ${this.state} -> ${state} (${args})`, "DATA:", this.data, func ? `THEN ${func.name}()` : undefined);
 
       this.transition(state);
       await func();
     } else {
-      log.debug(`FSM ${this.events.constructor.name}: (${event}) = ${this.state} -> ${next_state} (${args})`, "DATA:", this.data);
+      console.debug(`FSM ${this.events.constructor.name}: (${event}) = ${this.state} -> ${next_state} (${args})`, "DATA:", this.data);
       this.transition(next_state);
     }
 

js/fsm_test.mjs

@@ -0,0 +1,56 @@
+import FSM from "./fsm.mjs";
+import assert from "assert";
+
+const add_test = () => {
+  console.log("Additional function call on state transition passed.");
+}
+
+class TestMachine {
+  constructor(data) {
+    console.log("DATA IS", data);
+    this.data = data;
+  }
+
+  async open(state, inc) {
+    switch(state) {
+      case "START":
+        console.log("THIS", this);
+        this.data.count = this.data.count + inc;
+        return "OPEN";
+      default:
+        return "ERROR";
+    }
+  }
+
+  close(state, inc) {
+    switch(state) {
+      case "OPEN":
+        this.data.count = this.data.count + inc;
+        return ["CLOSED", add_test];
+      default:
+        return "ERROR";
+    }
+  }
+}
+
+
+let data = {count: 0};
+let events = new TestMachine(data);
+let fsm1 = new FSM(data, events);
+
+fsm1.onTransition((fsm) => {
+  console.log("On transition: ", fsm.state);
+});
+
+await fsm1.do('open', 3);
+assert(fsm1.state === "OPEN");
+assert(data.count === 3);
+
+await fsm1.do('close', 4);
+assert(fsm1.state === "CLOSED");
+assert(data.count === 7);
+
+// test the errors
+await fsm1.do('open');
+assert(fsm1.state === "ERROR");
+assert(data.count === 7); // still 2 after error