Add simple test for fs-writable

lib/fs-writable.js

@@ -93,7 +93,7 @@ class WriteStream extends Writable {
 
   _write(data, cb) {
     if (!(data instanceof Buffer)) {
-      const err = new Error();
+      const err = new ERR_INVALID_ARG_TYPE('data', 'Buffer', data);
       return this.emit('error', err);
     }
 

test/fs-writable.js

@@ -0,0 +1,53 @@
+'use strict';
+
+const fs = require('fs');
+const metatests = require('metatests');
+const WriteStream = require('../lib/fs-writable');
+
+
+metatests.testSync('fs-writable / create', test => {
+  const TEST_FILENAME = './create';
+
+  new WriteStream(TEST_FILENAME);
+
+  test.throws(() => new WriteStream());
+  test.throws(() => new WriteStream(1));
+  test.throws(() => new WriteStream(true));
+
+  test.throws(() => new WriteStream(TEST_FILENAME, { start: -1 }));
+
+  fs.unlinkSync(TEST_FILENAME);
+});
+
+metatests.test('fs-writable / open', test => {
+  const TEST_FILENAME = './open';
+
+  test.plan(2);
+
+  const stream = new WriteStream(TEST_FILENAME);
+  stream.on('open', () => test.pass('open'));
+  stream.on('ready', () => test.pass('ready'));
+
+  test.on('done', () => fs.unlinkSync(TEST_FILENAME));
+});
+
+metatests.test('fs-writable / write', test => {
+  const TEST_FILENAME = './write';
+
+  test.plan(1);
+
+  const stream = new WriteStream(TEST_FILENAME);
+
+  stream.write('123');
+  stream.write('456');
+  stream.cork();
+  stream.write('7');
+  stream.write('8');
+  stream.uncork();
+  stream.end('9', () => {
+    const writeData = fs.readFileSync(TEST_FILENAME).toString();
+    fs.unlinkSync(TEST_FILENAME);
+    test.strictSame(writeData, '123456789');
+  });
+});
+