Merge pull request #77 from marnusw/filterTransform

Implement filter as a Transform stream to fix piping

src/filter.ts

@@ -1,12 +1,11 @@
 import { Node } from '.'
-import { createDuplex } from './utils'
+import { Transform } from 'stream'
 
 export const filter = (callback: (node: Node) => boolean) =>
- createDuplex({
- write(chunk, _encoding, next) {
- if (callback(chunk)) {
- this.push(chunk)
- }
- next()
+ new Transform({
+ objectMode: true,
+ autoDestroy: false,
+ transform: function transform(chunk, _encoding, next) {
+ callback(chunk) ? next(null, chunk) : next()
  }
  })

test-utils.ts

@@ -60,3 +60,11 @@ export const pipeline = (stream: Readable): Promise<NodeList> =>
  stream.on('error', reject)
  stream.on('finish', () => resolve(buffer))
  })
+
+export const streamToString = (stream: Readable): Promise<string> =>
+ new Promise((resolve, reject) => {
+ let buffer = ''
+ stream.on('data', (chunk: string) => buffer += chunk)
+ stream.on('error', reject)
+ stream.on('finish', () => resolve(buffer))
+ })

test/filter.test.ts

@@ -1,5 +1,5 @@
-import { createStreamFromString, pipeline } from '../test-utils'
-import { filter, parse } from '../src'
+import { createStreamFromString, pipeline, streamToString } from '../test-utils'
+import { filter, parse, stringify } from '../src'
 
 test('filter nodes', async () => {
  const stream = createStreamFromString(`
@@ -44,3 +44,40 @@ Welcome to the Planet.\n`)
  ]
  `)
 })
+
+test('filter nodes and forward to the next stream', async () => {
+ const stream = createStreamFromString(`
+1
+02:12:34,647 --> 02:12:35,489
+Hi.
+
+2
+02:12:36,415 --> 02:12:37,758
+𝅘𝅥𝅮 Some Music 𝅘𝅥𝅮
+
+3
+02:12:38,584 --> 02:12:40,120
+Welcome to the Planet.\n`)
+
+ const data = await streamToString(
+ stream
+ .pipe(parse())
+ .pipe(
+ filter(node => !(node.type === 'cue' && node.data.text.includes('𝅘𝅥𝅮')))
+ )
+ .pipe(stringify({ format: 'WebVTT' }))
+ )
+
+ expect(data).toMatchInlineSnapshot(`
+ "WEBVTT
+
+ 1
+ 02:12:34.647 --> 02:12:35.489
+ Hi.
+
+ 2
+ 02:12:38.584 --> 02:12:40.120
+ Welcome to the Planet.
+ "
+ `)
+})