feat: Add bundle method

Adds a new `bundle` method to match the API of the JS writer. This allows you to instantiate a
writer a single time, but consume from it multiple times

BREAKING CHANGE: The user must now call `.bundle` before the writer can be consumed

.eslintrc

@@ -9,7 +9,6 @@
     "finn-prettier"
   ],
   "env": {
-    "node": true,
     "jest": true
   }
-}
+}

README.md

@@ -60,7 +60,7 @@ npm install asset-pipe-css-writer
 ### Require the writer
 
 ```js
-const CssWriter = require('asset-pipe-css-writer');
+const CssWriter = require('@asset-pipe/css-writer');
 ```
 
 ### Instantiating the writer
@@ -82,12 +82,12 @@ const writer = new CssWriter([
 
 ### Consuming content from the writer
 
-The writer is a readable stream in object mode so in order to access the data
-you may register a data handler and listen for objects to be passed to the
-handler:
+The writer is an event emitter, which has a method called `bundle`, which
+returns a readable stream in object mode so in order to access the data you may
+register a data handler and listen for objects to be passed to the handler:
 
 ```js
-writer.on('data', data => {
+writer.bundle().on('data', data => {
     // { id, name, version, file, content }
 });
 ```
@@ -96,7 +96,7 @@ You might also pipe the writer into a writeable or transform stream (with input
 in object mode):
 
 ```js
-const { Writable } = require('stream');
+const { Writeable } = require('stream');
 const consumer = new Writeable({
     objectMode: true,
     write(chunk, encoding, callback) {
@@ -106,5 +106,19 @@ const consumer = new Writeable({
     },
 });
 
-writer.pipe(consumer);
+writer.bundle().pipe(consumer);
+```
+
+If you want to create a single file output, send `true` as the second argument
+when creating the `Writer`.
+
+```js
+const writer = new CssWriter(
+    ['/path/to/css/file1.css', '/path/to/css/file2.css'],
+    true,
+);
+
+writer.bundle().on('data', data => {
+    // the two files bundled together as a single CSS
+});
 ```

lib/writer.js

@@ -1,16 +1,48 @@
 'use strict';
 
-const { Readable } = require('stream');
+const EventEmitter = require('events');
+const { Readable, Transform } = require('stream');
 const { identifyCssModule, bundleCssModule } = require('./util');
 const { existsSync } = require('fs');
 const { isAbsolute } = require('path');
 const assert = require('assert');
 const { hasher } = require('asset-pipe-common');
 
-module.exports = class Writer extends Readable {
-    constructor(files = []) {
+class Stream extends Readable {
+    constructor(files) {
         super({ objectMode: true });
 
+        this.files = files;
+    }
+
+    async _read() {
+        const file = this.files.shift();
+        if (!file) {
+            this.push(null);
+            return;
+        }
+
+        try {
+            const [css, meta] = await Promise.all([
+                bundleCssModule(file),
+                identifyCssModule(file),
+            ]);
+            meta.id = hasher(
+                `${meta.name}|${meta.version}|${meta.file}|${css}`
+            );
+            meta.content = css;
+            this.push(meta);
+        } catch (err) {
+            this.emit('error', err);
+        }
+    }
+}
+
+module.exports = class Writer extends EventEmitter {
+    constructor(files = [], bundle = false) {
+        super({ objectMode: true });
+        this.shouldBundle = bundle;
+
         assert(
             Array.isArray(files) || typeof files === 'string',
             `Expected 'files' to be of type 'Array' or a 'string', instead got '${typeof files}'`
@@ -38,25 +70,20 @@ module.exports = class Writer extends Readable {
         }
     }
 
-    async _read() {
-        const file = this.files.shift();
-        if (!file) {
-            this.push(null);
-            return;
-        }
+    bundle() {
+        const cssStream = new Stream(this.files.slice(0));
 
-        try {
-            const [css, meta] = await Promise.all([
-                bundleCssModule(file),
-                identifyCssModule(file),
-            ]);
-            meta.id = hasher(
-                `${meta.name}|${meta.version}|${meta.file}|${css}`
-            );
-            meta.content = css;
-            this.push(meta);
-        } catch (err) {
-            this.emit('error', err);
+        if (!this.shouldBundle) {
+            return cssStream;
         }
+
+        return cssStream.pipe(
+            new Transform({
+                objectMode: true,
+                transform(chunk, enc, next) {
+                    next(null, chunk.content);
+                },
+            })
+        );
     }
 };

test/writer.test.js

@@ -1,7 +1,6 @@
 'use strict';
 
-/* global test, expect, beforeEach, jest */
-
+const fs = require('fs');
 const path = require('path');
 const { hasher } = require('asset-pipe-common');
 const { identifyCssModule, bundleCssModule } = require('../lib/util.js');
@@ -64,7 +63,7 @@ test('new Writer(filePath)', done => {
     const filePath = path.join(__dirname, 'test-assets/my-module-1/main.css');
     const fileRef = 'my-module-1/main.css';
 
-    const writer = new Writer(filePath);
+    const writer = new Writer(filePath).bundle();
     const items = [];
 
     writer.on('data', item => {
@@ -82,6 +81,31 @@ test('new Writer(filePath)', done => {
     });
 });
 
+test('new Writer(filePath) can be reused', done => {
+    expect.assertions(2);
+    const filePath = path.join(__dirname, 'test-assets/my-module-1/main.css');
+    const dataMock = jest.fn();
+
+    const writer = new Writer(filePath);
+    const bundle1 = writer.bundle();
+
+    bundle1.on('data', dataMock);
+
+    bundle1.on('end', () => {
+        expect(dataMock).toHaveBeenCalledTimes(1);
+
+        const bundle2 = writer.bundle();
+
+        bundle2.on('data', dataMock);
+
+        bundle2.on('end', () => {
+            expect(dataMock).toHaveBeenCalledTimes(2);
+
+            done();
+        });
+    });
+});
+
 test('new Writer(filePath) relative paths throw error', () => {
     expect.assertions(1);
     const filePath = './test-assets/my-module-1/main.css';
@@ -96,7 +120,7 @@ test('new Writer([filePath])', done => {
     const filePath = path.join(__dirname, 'test-assets/my-module-1/main.css');
     const fileRef = 'my-module-1/main.css';
 
-    const writer = new Writer([filePath]);
+    const writer = new Writer([filePath]).bundle();
     const items = [];
 
     writer.on('data', item => {
@@ -122,7 +146,7 @@ test('Writer processes @import statements', done => {
     );
     const fileRef = 'my-module-3/css/main.css';
 
-    const writer = new Writer([filePath]);
+    const writer = new Writer([filePath]).bundle();
     const items = [];
 
     writer.on('data', item => {
@@ -154,7 +178,7 @@ test('new Writer([filePath1, filePath2]) ensures correct order', done => {
     );
     const fileRef2 = 'my-module-2/css/main.css';
 
-    const writer = new Writer([filePath1, filePath2]);
+    const writer = new Writer([filePath1, filePath2]).bundle();
     const items = [];
 
     writer.on('data', item => {
@@ -244,7 +268,7 @@ test('writer emits error', done => {
     const CssWriter = require('..');
     const filePath = path.join(__dirname, 'test-assets/my-module-1/main.css');
 
-    const writer = new CssWriter(filePath);
+    const writer = new CssWriter(filePath).bundle();
 
     writer.on('error', error => {
         expect(error).toBeInstanceOf(Error);
@@ -254,7 +278,7 @@ test('writer emits error', done => {
 });
 
 test('new Writer() emits nothing but does not break', done => {
-    const writer = new Writer();
+    const writer = new Writer().bundle();
     const items = [];
 
     writer.on('data', item => {
@@ -266,3 +290,25 @@ test('new Writer() emits nothing but does not break', done => {
         done();
     });
 });
+
+test('new Writer(filepath, bundle: true) emits a bundle', done => {
+    expect.assertions(1);
+    const filePath = path.join(__dirname, 'test-assets/my-module-1/main.css');
+
+    const writer = new Writer([filePath], true).bundle();
+
+    writer.on('error', e => {
+        done.fail(e);
+    });
+    const items = [];
+
+    writer.on('data', item => {
+        items.push(item);
+    });
+
+    writer.on('end', () => {
+        expect(items).toEqual([fs.readFileSync(filePath, 'utf8')]);
+
+        done();
+    });
+});