chore(writeStream): refactor function and improve test

src/api/viya/spec/writeStream.spec.ts

@@ -1,24 +1,34 @@
 import { WriteStream } from '../../../types'
 import { writeStream } from '../writeStream'
-import 'jest-extended'
+import {
+  createWriteStream,
+  fileExists,
+  readFile,
+  deleteFile
+} from '@sasjs/utils'
 
 describe('writeStream', () => {
-  const stream: WriteStream = {
-    write: jest.fn(),
-    path: 'test'
-  }
+  const filename = 'test.txt'
+  const content = 'test'
+  let stream: WriteStream
+
+  beforeAll(async () => {
+    stream = await createWriteStream(filename)
+  })
 
   it('should resolve when the stream is written successfully', async () => {
-    expect(writeStream(stream, 'test')).toResolve()
+    await expect(writeStream(stream, content)).toResolve()
+    await expect(fileExists(filename)).resolves.toEqual(true)
+    await expect(readFile(filename)).resolves.toEqual(content + '\n')
 
-    expect(stream.write).toHaveBeenCalledWith('test\n', expect.anything())
+    await deleteFile(filename)
   })
 
   it('should reject when the write errors out', async () => {
     jest
       .spyOn(stream, 'write')
       .mockImplementation((_, callback) => callback(new Error('Test Error')))
-    const error = await writeStream(stream, 'test').catch((e) => e)
+    const error = await writeStream(stream, content).catch((e) => e)
 
     expect(error.message).toEqual('Test Error')
   })

src/api/viya/writeStream.ts

@@ -3,13 +3,9 @@ import { WriteStream } from '../../types'
 export const writeStream = async (
   stream: WriteStream,
   content: string
-): Promise<void> => {
-  return new Promise((resolve, reject) => {
-    stream.write(content + '\n', (e) => {
-      if (e) {
-        return reject(e)
-      }
-      return resolve()
-    })
+): Promise<void> =>
+  stream.write(content + '\n', (e) => {
+    if (e) return Promise.reject(e)
+
+    return Promise.resolve()
   })
-}