From 71ad3c6107d3dabd674cb34cc4aa21544be1f24a Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Thu, 8 Aug 2019 11:18:39 +0200
Subject: [PATCH 1/2] fs: remove unnecessary argument check

---
 lib/internal/fs/streams.js            |  9 +++------
 test/parallel/test-fs-write-stream.js | 15 +--------------
 2 files changed, 4 insertions(+), 20 deletions(-)

diff --git a/lib/internal/fs/streams.js b/lib/internal/fs/streams.js
index d51fbb1b580113..d923e8ab6b23fa 100644
--- a/lib/internal/fs/streams.js
+++ b/lib/internal/fs/streams.js
@@ -3,7 +3,6 @@
 const { Math, Object } = primordials;
 
 const {
-  ERR_INVALID_ARG_TYPE,
   ERR_OUT_OF_RANGE
 } = require('internal/errors').codes;
 const { validateNumber } = require('internal/validators');
@@ -238,6 +237,9 @@ function WriteStream(path, options) {
 
   options = copyObject(getOptions(options, {}));
 
+  // Only buffers are supported.
+  options.decodeStrings = true;
+
   // For backwards compat do not emit close on destroy.
   if (options.emitClose === undefined) {
     options.emitClose = false;
@@ -298,11 +300,6 @@ WriteStream.prototype.open = function() {
 
 
 WriteStream.prototype._write = function(data, encoding, cb) {
-  if (!(data instanceof Buffer)) {
-    const err = new ERR_INVALID_ARG_TYPE('data', 'Buffer', data);
-    return this.emit('error', err);
-  }
-
   if (typeof this.fd !== 'number') {
     return this.once('open', function() {
       this._write(data, encoding, cb);
diff --git a/test/parallel/test-fs-write-stream.js b/test/parallel/test-fs-write-stream.js
index 5e75f4a0b306d2..6d263f450b6a4b 100644
--- a/test/parallel/test-fs-write-stream.js
+++ b/test/parallel/test-fs-write-stream.js
@@ -20,7 +20,7 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 'use strict';
-const common = require('../common');
+require('../common');
 const assert = require('assert');
 const path = require('path');
 const fs = require('fs');
@@ -52,16 +52,3 @@ tmpdir.refresh();
   });
   stream.destroy();
 }
-
-// Throws if data is not of type Buffer.
-{
-  const stream = fs.createWriteStream(file);
-  common.expectsError(() => {
-    stream._write(42, null, function() {});
-  }, {
-    code: 'ERR_INVALID_ARG_TYPE',
-    type: TypeError,
-    message: 'The "data" argument must be of type Buffer. Received type number'
-  });
-  stream.destroy();
-}

From 3b53003b6dfc470220bd0af7d8b5304f175490b5 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Mon, 26 Aug 2019 20:21:22 +0200
Subject: [PATCH 2/2] fixup

---
 test/parallel/test-fs-write-stream.js | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/test/parallel/test-fs-write-stream.js b/test/parallel/test-fs-write-stream.js
index 6d263f450b6a4b..18374f44ebcdad 100644
--- a/test/parallel/test-fs-write-stream.js
+++ b/test/parallel/test-fs-write-stream.js
@@ -20,7 +20,7 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const path = require('path');
 const fs = require('fs');
@@ -52,3 +52,17 @@ tmpdir.refresh();
   });
   stream.destroy();
 }
+
+// Throws if data is not of type Buffer.
+{
+  const stream = fs.createWriteStream(file);
+  stream.on('error', common.expectsError({
+    code: 'ERR_INVALID_ARG_TYPE',
+    type: TypeError
+  }));
+  stream.write(42, null, common.expectsError({
+    code: 'ERR_INVALID_ARG_TYPE',
+    type: TypeError
+  }));
+  stream.destroy();
+}