updated on method overload to include generic method call

Author: chris-pardy

types/index.d.ts

@@ -51,9 +51,7 @@ export class Engine {
   removeFact(factOrId: string | Fact): boolean;
   getFact<T>(factId: string): Fact<T>;
 
-  on(eventName: "success", handler: EventHandler): this;
-  on(eventName: "failure", handler: EventHandler): this;
-  on(eventName: string, handler: EventHandler): this;
+  on<T = Event>(eventName: string, handler: EventHandler<T>): this;
 
   run(facts?: Record<string, any>, runOptions?: RunOptions): Promise<EngineResult>;
   stop(): this;
@@ -119,8 +117,8 @@ export interface Event {
 
 export type PathResolver = (value: object, path: string) => any;
 
-export type EventHandler = (
-  event: Event,
+export type EventHandler<T = Event> = (
+  event: T,
   almanac: Almanac,
   ruleResult: RuleResult
 ) => void;

types/index.test-d.ts

@@ -4,12 +4,14 @@ import rulesEngine, {
   Almanac,
   EngineResult,
   Engine,
+  Event,
   Fact,
   Operator,
   OperatorEvaluator,
   PathResolver,
   Rule,
   RuleProperties,
+  RuleResult,
   RuleSerializable
 } from "../";
 
@@ -93,6 +95,16 @@ expectType<Engine>(engine.addFact(fact));
 expectType<Engine>(engine.addFact(dynamicFact));
 expectType<boolean>(engine.removeFact(fact));
 expectType<Fact<string>>(engine.getFact<string>("test"));
+engine.on('success', (event, almanac, ruleResult) => {
+  expectType<Event>(event)
+  expectType<Almanac>(almanac)
+  expectType<RuleResult>(ruleResult)
+})
+engine.on<{ foo: Array<string> }>('foo', (event, almanac, ruleResult) => {
+  expectType<{ foo: Array<string> }>(event)
+  expectType<Almanac>(almanac)
+  expectType<RuleResult>(ruleResult)
+})
 
 // Run the Engine
 expectType<Promise<EngineResult>>(engine.run({ displayMessage: true }));