[7.x] Move streams utils to the core (#76397)

.eslintrc.js

@@ -311,6 +311,8 @@ module.exports = {
                   '!src/core/server/mocks{,.ts}',
                   '!src/core/server/types{,.ts}',
                   '!src/core/server/test_utils{,.ts}',
+                  '!src/core/server/utils', // ts alias
+                  '!src/core/server/utils/**/*',
                   // for absolute imports until fixed in
                   // https://github.com/elastic/kibana/issues/36096
                   '!src/core/server/*.test.mocks{,.ts}',

src/cli_keystore/add.js

@@ -19,7 +19,7 @@
 
 import { Logger } from '../cli_plugin/lib/logger';
 import { confirm, question } from '../legacy/server/utils';
-import { createPromiseFromStreams, createConcatStream } from '../legacy/utils';
+import { createPromiseFromStreams, createConcatStream } from '../core/server/utils';
 
 /**
  * @param {Keystore} keystore

src/core/server/saved_objects/export/get_sorted_objects_for_export.test.ts

@@ -20,7 +20,7 @@
 import { exportSavedObjectsToStream } from './get_sorted_objects_for_export';
 import { savedObjectsClientMock } from '../service/saved_objects_client.mock';
 import { Readable } from 'stream';
-import { createPromiseFromStreams, createConcatStream } from '../../../../legacy/utils/streams';
+import { createPromiseFromStreams, createConcatStream } from '../../utils/streams';
 
 async function readStreamToCompletion(stream: Readable) {
   return createPromiseFromStreams([stream, createConcatStream([])]);

src/core/server/saved_objects/export/get_sorted_objects_for_export.ts

@@ -18,7 +18,7 @@
  */
 
 import Boom from 'boom';
-import { createListStream } from '../../../../legacy/utils/streams';
+import { createListStream } from '../../utils/streams';
 import { SavedObjectsClientContract, SavedObject } from '../types';
 import { fetchNestedDependencies } from './inject_nested_depdendencies';
 import { sortObjects } from './sort_objects';

src/core/server/saved_objects/import/collect_saved_objects.ts

@@ -23,7 +23,7 @@ import {
   createFilterStream,
   createMapStream,
   createPromiseFromStreams,
-} from '../../../../legacy/utils/streams';
+} from '../../utils/streams';
 import { SavedObject } from '../types';
 import { createLimitStream } from './create_limit_stream';
 import { SavedObjectsImportError } from './types';

src/core/server/saved_objects/import/create_limit_stream.test.ts

@@ -21,7 +21,7 @@ import {
   createConcatStream,
   createListStream,
   createPromiseFromStreams,
-} from '../../../../legacy/utils/streams';
+} from '../../utils/streams';
 import { createLimitStream } from './create_limit_stream';
 
 describe('createLimitStream()', () => {

src/core/server/saved_objects/routes/export.ts

@@ -19,11 +19,7 @@
 
 import { schema } from '@kbn/config-schema';
 import stringify from 'json-stable-stringify';
-import {
-  createPromiseFromStreams,
-  createMapStream,
-  createConcatStream,
-} from '../../../../legacy/utils/streams';
+import { createPromiseFromStreams, createMapStream, createConcatStream } from '../../utils/streams';
 import { IRouter } from '../../http';
 import { SavedObjectConfig } from '../saved_objects_config';
 import { exportSavedObjectsToStream } from '../export';

src/core/server/saved_objects/routes/integration_tests/export.test.ts

@@ -22,7 +22,7 @@ jest.mock('../../export', () => ({
 }));
 
 import * as exportMock from '../../export';
-import { createListStream } from '../../../../../legacy/utils/streams';
+import { createListStream } from '../../../utils/streams';
 import supertest from 'supertest';
 import { UnwrapPromise } from '@kbn/utility-types';
 import { SavedObjectConfig } from '../../saved_objects_config';

src/core/server/saved_objects/routes/utils.test.ts

@@ -19,7 +19,7 @@
 
 import { createSavedObjectsStreamFromNdJson, validateTypes, validateObjects } from './utils';
 import { Readable } from 'stream';
-import { createPromiseFromStreams, createConcatStream } from '../../../../legacy/utils/streams';
+import { createPromiseFromStreams, createConcatStream } from '../../utils/streams';
 
 async function readStreamToCompletion(stream: Readable) {
   return createPromiseFromStreams([stream, createConcatStream([])]);

src/core/server/saved_objects/routes/utils.ts

@@ -19,11 +19,7 @@
 
 import { Readable } from 'stream';
 import { SavedObject, SavedObjectsExportResultDetails } from 'src/core/server';
-import {
-  createSplitStream,
-  createMapStream,
-  createFilterStream,
-} from '../../../../legacy/utils/streams';
+import { createSplitStream, createMapStream, createFilterStream } from '../../utils/streams';
 
 export function createSavedObjectsStreamFromNdJson(ndJsonStream: Readable) {
   return ndJsonStream

src/core/server/utils/index.ts

@@ -20,3 +20,4 @@
 export * from './crypto';
 export * from './from_root';
 export * from './package_json';
+export * from './streams';

src/legacy/utils/streams/concat_stream.test.js → src/core/server/utils/streams/concat_stream.test.ts

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-import { createListStream, createPromiseFromStreams, createConcatStream } from './';
+import { createListStream, createPromiseFromStreams, createConcatStream } from './index';
 
 describe('concatStream', () => {
   test('accepts an initial value', async () => {

src/legacy/utils/streams/concat_stream.js → src/core/server/utils/streams/concat_stream.ts

@@ -41,6 +41,6 @@ import { createReduceStream } from './reduce_stream';
  *                       items will concat with
  *  @return {Transform}
  */
-export function createConcatStream(initial) {
+export function createConcatStream<T>(initial?: T) {
   return createReduceStream((acc, chunk) => acc.concat(chunk), initial);
 }

src/legacy/utils/streams/concat_stream_providers.js → src/core/server/utils/streams/concat_stream_providers.ts

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-import { PassThrough } from 'stream';
+import { Readable, PassThrough, TransformOptions } from 'stream';
 
 /**
  *  Write the data and errors from a list of stream providers
@@ -29,7 +29,10 @@ import { PassThrough } from 'stream';
  *  @param {PassThroughOptions} options options passed to the PassThrough constructor
  *  @return {WritableStream} combined stream
  */
-export function concatStreamProviders(sourceProviders, options = {}) {
+export function concatStreamProviders(
+  sourceProviders: Array<() => Readable>,
+  options?: TransformOptions
+) {
   const destination = new PassThrough(options);
   const queue = sourceProviders.slice();
 

src/legacy/utils/streams/filter_stream.test.ts → src/core/server/utils/streams/filter_stream.test.ts

@@ -22,7 +22,7 @@ import {
   createFilterStream,
   createListStream,
   createPromiseFromStreams,
-} from './';
+} from './index';
 
 describe('createFilterStream()', () => {
   test('calls the function with each item in the source stream', async () => {

src/legacy/utils/streams/intersperse_stream.test.js → src/core/server/utils/streams/intersperse_stream.test.ts

@@ -22,7 +22,7 @@ import {
   createListStream,
   createIntersperseStream,
   createConcatStream,
-} from './';
+} from './index';
 
 describe('intersperseStream', () => {
   test('places the intersperse value between each provided value', async () => {

src/legacy/utils/streams/intersperse_stream.js → src/core/server/utils/streams/intersperse_stream.ts

@@ -40,7 +40,7 @@ import { Transform } from 'stream';
  *  @param  {String|Buffer} intersperseChunk
  *  @return {Transform}
  */
-export function createIntersperseStream(intersperseChunk) {
+export function createIntersperseStream(intersperseChunk: string | Buffer) {
   let first = true;
 
   return new Transform({
@@ -55,7 +55,7 @@ export function createIntersperseStream(intersperseChunk) {
         }
 
         this.push(chunk);
-        callback(null);
+        callback();
       } catch (err) {
         callback(err);
       }

src/legacy/utils/streams/list_stream.test.js → src/core/server/utils/streams/list_stream.test.ts

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-import { createListStream } from './';
+import { createListStream } from './index';
 
 describe('listStream', () => {
   test('provides the values in the initial list', async () => {

src/legacy/utils/streams/list_stream.js → src/core/server/utils/streams/list_stream.ts

@@ -26,8 +26,8 @@ import { Readable } from 'stream';
  *  @param  {Array<any>} items - the list of items to provide
  *  @return {Readable}
  */
-export function createListStream(items = []) {
-  const queue = [].concat(items);
+export function createListStream<T = any>(items: T | T[] = []) {
+  const queue = Array.isArray(items) ? [...items] : [items];
 
   return new Readable({
     objectMode: true,

src/legacy/utils/streams/map_stream.test.js → src/core/server/utils/streams/map_stream.test.ts

@@ -39,7 +39,7 @@ describe('createMapStream()', () => {
   test('send the return value from the mapper on the output stream', async () => {
     const result = await createPromiseFromStreams([
       createListStream([1, 2, 3]),
-      createMapStream((n) => n * 100),
+      createMapStream((n: number) => n * 100),
       createConcatStream([]),
     ]);
 
@@ -49,7 +49,7 @@ describe('createMapStream()', () => {
   test('supports async mappers', async () => {
     const result = await createPromiseFromStreams([
       createListStream([1, 2, 3]),
-      createMapStream(async (n, i) => {
+      createMapStream(async (n: number, i: number) => {
         await delay(n);
         return n * i;
       }),

src/legacy/utils/streams/map_stream.js → src/core/server/utils/streams/map_stream.ts

@@ -19,7 +19,7 @@
 
 import { Transform } from 'stream';
 
-export function createMapStream(fn) {
+export function createMapStream<T>(fn: (value: T, i: number) => void) {
   let i = 0;
 
   return new Transform({

src/legacy/utils/streams/promise_from_streams.test.js → src/core/server/utils/streams/promise_from_streams.test.ts

@@ -19,7 +19,7 @@
 
 import { Readable, Writable, Duplex, Transform } from 'stream';
 
-import { createListStream, createPromiseFromStreams, createReduceStream } from './';
+import { createListStream, createPromiseFromStreams, createReduceStream } from './index';
 
 describe('promiseFromStreams', () => {
   test('pipes together an array of streams', async () => {
@@ -76,14 +76,13 @@ describe('promiseFromStreams', () => {
     test('waits for writing and resolves to final value', async () => {
       let written = '';
 
-      const duplexReadQueue = [];
+      const duplexReadQueue: Array<Promise<unknown>> = [];
       const duplexItemsToPush = ['foo', 'bar', null];
       const result = await createPromiseFromStreams([
         createListStream(['a', 'b', 'c']),
         new Duplex({
           async read() {
-            const result = await duplexReadQueue.shift();
-            this.push(result);
+            this.push(await duplexReadQueue.shift());
           },
 
           write(chunk, enc, cb) {

src/legacy/utils/streams/promise_from_streams.js → src/core/server/utils/streams/promise_from_streams.ts

@@ -34,16 +34,20 @@
  *  @return {Promise<any>}
  */
 
-import { pipeline, Writable } from 'stream';
+import { pipeline, Writable, Readable } from 'stream';
 
-export async function createPromiseFromStreams(streams) {
-  let finalChunk;
+function isReadable(stream: Readable | Writable): stream is Readable {
+  return 'read' in stream && typeof stream.read === 'function';
+}
+
+export async function createPromiseFromStreams<T>(streams: [Readable, ...Writable[]]): Promise<T> {
+  let finalChunk: any;
   const last = streams[streams.length - 1];
-  if (typeof last.read !== 'function' && streams.length === 1) {
+  if (!isReadable(last) && streams.length === 1) {
     // For a nicer error than what stream.pipeline throws
     throw new Error('A minimum of 2 streams is required when a non-readable stream is given');
   }
-  if (typeof last.read === 'function') {
+  if (isReadable(last)) {
     // We are pushing a writable stream to capture the last chunk
     streams.push(
       new Writable({
@@ -57,7 +61,9 @@ export async function createPromiseFromStreams(streams) {
       })
     );
   }
+
   return new Promise((resolve, reject) => {
+    // @ts-expect-error 'pipeline' doesn't support variable length of arguments
     pipeline(...streams, (err) => {
       if (err) return reject(err);
       resolve(finalChunk);

src/legacy/utils/streams/reduce_stream.test.js → src/core/server/utils/streams/reduce_stream.test.ts

@@ -16,10 +16,10 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+import { Transform } from 'stream';
+import { createReduceStream, createPromiseFromStreams, createListStream } from './index';
 
-import { createReduceStream, createPromiseFromStreams, createListStream } from './';
-
-const promiseFromEvent = (name, emitter) =>
+const promiseFromEvent = (name: string, emitter: Transform) =>
   new Promise((resolve) => emitter.on(name, () => resolve(name)));
 
 describe('reduceStream', () => {
@@ -47,7 +47,10 @@ describe('reduceStream', () => {
   });
 
   test('emits an error if an iteration fails', async () => {
-    const reduce = createReduceStream((acc, i) => expect(i).toBe(1), 0);
+    const reduce = createReduceStream((acc, i) => {
+      expect(i).toBe(1);
+      return acc;
+    }, 0);
     const errorEvent = promiseFromEvent('error', reduce);
 
     reduce.write(1);

src/legacy/utils/streams/reduce_stream.js → src/core/server/utils/streams/reduce_stream.ts

@@ -32,7 +32,10 @@ import { Transform } from 'stream';
  *                        initial value.
  *  @return {Transform}
  */
-export function createReduceStream(reducer, initial) {
+export function createReduceStream<T>(
+  reducer: (value: any, chunk: T, enc: string) => T,
+  initial?: T
+) {
   let i = -1;
   let value = initial;
 

src/legacy/utils/streams/replace_stream.test.js → src/core/server/utils/streams/replace_stream.test.ts

@@ -16,26 +16,27 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+import { Writable, Readable } from 'stream';
 
 import {
   createReplaceStream,
   createConcatStream,
   createPromiseFromStreams,
   createListStream,
   createMapStream,
-} from './';
+} from './index';
 
-async function concatToString(streams) {
+async function concatToString(streams: [Readable, ...Writable[]]) {
   return await createPromiseFromStreams([
     ...streams,
-    createMapStream((buff) => buff.toString('utf8')),
+    createMapStream((buff: Buffer) => buff.toString('utf8')),
     createConcatStream(''),
   ]);
 }
 
 describe('replaceStream', () => {
   test('produces buffers when it receives buffers', async () => {
-    const chunks = await createPromiseFromStreams([
+    const chunks = await createPromiseFromStreams<Buffer[]>([
       createListStream([Buffer.from('foo'), Buffer.from('bar')]),
       createReplaceStream('o', '0'),
       createConcatStream([]),
@@ -47,7 +48,7 @@ describe('replaceStream', () => {
   });
 
   test('produces buffers when it receives strings', async () => {
-    const chunks = await createPromiseFromStreams([
+    const chunks = await createPromiseFromStreams<string[]>([
       createListStream(['foo', 'bar']),
       createReplaceStream('o', '0'),
       createConcatStream([]),
@@ -59,6 +60,7 @@ describe('replaceStream', () => {
   });
 
   test('expects toReplace to be a string', () => {
+    // @ts-expect-error
     expect(() => createReplaceStream(Buffer.from('foo'))).toThrowError(/be a string/);
   });
 

src/legacy/utils/streams/replace_stream.js → src/core/server/utils/streams/replace_stream.ts

@@ -19,7 +19,7 @@
 
 import { Transform } from 'stream';
 
-export function createReplaceStream(toReplace, replacement) {
+export function createReplaceStream(toReplace: string, replacement: string | Buffer) {
   if (typeof toReplace !== 'string') {
     throw new TypeError('toReplace must be a string');
   }
@@ -78,6 +78,7 @@ export function createReplaceStream(toReplace, replacement) {
         this.push(buffer);
       }
 
+      // @ts-expect-error
       buffer = null;
       callback();
     },