better error handling when loading tasks using esm

Author: abendigo

.editorconfig

@@ -0,0 +1,3 @@
+[*]
+indent_size = 2
+indent_style = space

.mocharc.json

@@ -1,5 +1,9 @@
 {
   "require": ["./env.js"],
   "extension": ["ts"],
-  "recursive": true
+  "recursive": true,
+  "node-option": [
+    "experimental-specifier-resolution=node",
+    "loader=ts-node/esm"
+  ]
 }

src/asyncAssignTasks.ts

@@ -17,15 +17,16 @@ export default async function asyncAssignTasks<T>(thisObj: T, tasksDir: string):
 
   async function loadTask(name: string) {
     const path = `${tasksDir}/${name}`
-    try {
-      // Typescript has issues with dynamic imports, even though node supports them
-      // for both commonjs and esmodules. see: https://github.com/microsoft/TypeScript/issues/43329
-      const task = await Function(`return import("${path}")`)()
-      return task[name]
-    } catch (err) {
-      return () => {
-        throw new Error(`No task in: ${path}.{ts,js,tsx,jsx}`)
-      }
+    // Typescript has issues with dynamic imports, even though node supports them
+    // for both commonjs and esmodules. see: https://github.com/microsoft/TypeScript/issues/43329
+    const task = await Function(`return import("${path}")`)()
+
+    // if typescript is using commonjs modules
+    if (task.default) {
+      return task.default[name]
     }
+
+    // if typescript is using es modules
+    return task[name]
   }
 }

test/asyncTasks.test.ts

@@ -0,0 +1,38 @@
+import assert = require('assert')
+import { Action, ActorWorld } from '../src'
+import type { IActorWorldOptions } from '../src/ActorWorld'
+import asyncAssignTasks from '../src/asyncAssignTasks'
+
+describe(asyncAssignTasks.name, () => {
+  const options: IActorWorldOptions = { parameters: {} } as IActorWorldOptions
+
+  // success
+  it('successfully loads a task', async () => {
+    class TestWorld extends ActorWorld {
+      public goodtask: () => Action<void>
+    }
+
+    const world = new TestWorld(options)
+
+    // Load the task
+    await asyncAssignTasks(world, `${__dirname}/fixtures/tasks/goodtasks`)
+
+    // Execute the task
+    world.goodtask()
+  })
+
+  // error compiling
+  it('fails with a helpful error message if the task could not be compiled', async () => {
+    class TestWorld extends ActorWorld {
+      public brokentask: () => Action<void>
+    }
+
+    const world = new TestWorld(options)
+
+    // Try to load the task
+    await assert.rejects(asyncAssignTasks(world, `${__dirname}/fixtures/tasks/brokentask`), {
+      name: 'TSError',
+      message: /Cannot find module '\.\/src'/,
+    })
+  })
+})

test/fixtures/tasks/brokentask/brokentask.ts

@@ -0,0 +1,7 @@
+// this import will fail
+import { type Action } from './src'
+
+export const badtask = (): Action => {
+  // eslint-disable-next-line @typescript-eslint/no-empty-function
+  return () => {}
+}

test/fixtures/tasks/goodtasks/goodtask.ts

@@ -0,0 +1,6 @@
+import { type Action } from '../../../../src'
+
+export const goodtask = (): Action<void> => {
+  // eslint-disable-next-line @typescript-eslint/no-empty-function
+  return () => {}
+}