⚡ Call 'reject' rather than throwing Error

Signed-off-by: kei-g <km.8k6ce+github@gmail.com>

Author: kei-g

async-iterable-queue.ts

@@ -93,28 +93,32 @@ export class AsyncIterableQueue<T> implements AsyncIterable<T> {
    * @param cb 終端が読み取られた後に呼ばれるコールバック関数
    */
   end(cb?: NoParameterCallback): Promise<void> {
-    const state = this.#state
-    if (state)
-      throw new Error(state)
-    this.#state = 'ending'
-    return new Promise((resolve: Resolver<void>) => (
-      this.#emitter.emit('enq', new Terminator(cb)),
-      resolve()
-    ))
+    return new Promise(
+      (resolve: Resolver<void>, reject: SingleParameterAction<unknown>) => {
+        const state = this.#state
+        if (state)
+          return reject(new Error(state))
+        this.#state = 'ending'
+        this.#emitter.emit('enq', new Terminator(cb))
+        return resolve()
+      }
+    )
   }
 
   /**
    * この待ち行列の末尾に要素を追加する
    * @param value 要素の値
    */
   push(value: T): Promise<void> {
-    const state = this.#state
-    if (state)
-      throw new Error(state)
-    return new Promise((resolve: Resolver<void>) => (
-      this.#emitter.emit('enq', value),
-      resolve()
-    ))
+    return new Promise(
+      (resolve: Resolver<void>, reject: SingleParameterAction<unknown>) => {
+        const state = this.#state
+        if (state)
+          return reject(new Error(state))
+        this.#emitter.emit('enq', value)
+        return resolve()
+      }
+    )
   }
 
   /**
@@ -185,15 +189,12 @@ class Terminator {
         try {
           const result = this.cb()
           if (result instanceof Promise)
-            result.catch(reject).then(resolve)
-          else
-            resolve()
+            return result.catch(reject).then(resolve)
         }
         catch (err: unknown) {
-          reject(err)
+          return reject(err)
         }
-      else
-        resolve()
+      return resolve()
     })
   }
 }

test/async-iterable-queue.spec.ts

@@ -1,7 +1,6 @@
 import { AsyncIterableQueue } from '../async-iterable-queue'
 import { describe, it } from 'mocha'
 import { expect } from 'chai'
-import { throws } from 'assert'
 
 const source = [
   Math.LN2,
@@ -23,7 +22,13 @@ describe('failure mission', async () => {
       for (const value of source)
         await q.push(value)
       await q.end()
-      throws(() => q.end())
+      let error: Error
+      await q.end()
+        .catch((reason: unknown) => {
+          if (reason instanceof Error)
+            error = reason
+        })
+        .finally(() => expect(error).instanceOf(Error))
     }
     await Promise.all([popAsync(q), pushAsync()])
   })
@@ -33,7 +38,13 @@ describe('failure mission', async () => {
       for (const value of source)
         await q.push(value)
       await q.end()
-      throws(() => q.push(Math.SQRT2))
+      let error: Error
+      await q.push(Math.SQRT2)
+        .catch((reason?: unknown) => {
+          if (reason instanceof Error)
+            error = reason
+        })
+        .finally(() => expect(error).instanceOf(Error))
     }
     await Promise.all([popAsync(q), pushAsync()])
   })
@@ -44,7 +55,7 @@ describe('failure mission', async () => {
         await q.push(value)
       await q.end(() => {
         throw new Error()
-      })
+      }).catch((reason?: unknown) => expect(reason).instanceOf(Error))
     }
     await Promise.all([popAsync(q), pushAsync()])
   })