diff --git a/test/parallel/test-buffer-bytelength.js b/test/parallel/test-buffer-bytelength.js
index c30e06cc73690d..b14047893370f2 100644
--- a/test/parallel/test-buffer-bytelength.js
+++ b/test/parallel/test-buffer-bytelength.js
@@ -16,6 +16,8 @@ assert.throws(() => { Buffer.byteLength({}, 'latin1'); },
 assert.throws(() => { Buffer.byteLength(); },
               /"string" must be a string, Buffer, or ArrayBuffer/);
 
+assert.strictEqual(Buffer.byteLength('', undefined, true), -1);
+
 assert(ArrayBuffer.isView(new Buffer(10)));
 assert(ArrayBuffer.isView(new SlowBuffer(10)));
 assert(ArrayBuffer.isView(Buffer.alloc(10)));
@@ -76,6 +78,7 @@ assert.strictEqual(Buffer.byteLength('ßœ∑≈', 'unkn0wn enc0ding'), 10);
 
 // base64
 assert.strictEqual(Buffer.byteLength('aGVsbG8gd29ybGQ=', 'base64'), 11);
+assert.strictEqual(Buffer.byteLength('aGVsbG8gd29ybGQ=', 'BASE64'), 11);
 assert.strictEqual(Buffer.byteLength('bm9kZS5qcyByb2NrcyE=', 'base64'), 14);
 assert.strictEqual(Buffer.byteLength('aGkk', 'base64'), 3);
 assert.strictEqual(
@@ -87,12 +90,18 @@ assert.strictEqual(Buffer.byteLength('aaaa==', 'base64'), 3);
 
 assert.strictEqual(Buffer.byteLength('Il était tué'), 14);
 assert.strictEqual(Buffer.byteLength('Il était tué', 'utf8'), 14);
-assert.strictEqual(Buffer.byteLength('Il était tué', 'ascii'), 12);
-assert.strictEqual(Buffer.byteLength('Il était tué', 'latin1'), 12);
-assert.strictEqual(Buffer.byteLength('Il était tué', 'binary'), 12);
-['ucs2', 'ucs-2', 'utf16le', 'utf-16le'].forEach(function(encoding) {
-  assert.strictEqual(24, Buffer.byteLength('Il était tué', encoding));
-});
+
+['ascii', 'latin1', 'binary']
+  .reduce((es, e) => es.concat(e, e.toUpperCase()), [])
+  .forEach((encoding) => {
+    assert.strictEqual(Buffer.byteLength('Il était tué', encoding), 12);
+  });
+
+['ucs2', 'ucs-2', 'utf16le', 'utf-16le']
+  .reduce((es, e) => es.concat(e, e.toUpperCase()), [])
+  .forEach((encoding) => {
+    assert.strictEqual(Buffer.byteLength('Il était tué', encoding), 24);
+  });
 
 // Test that ArrayBuffer from a different context is detected correctly
 const arrayBuf = vm.runInNewContext('new ArrayBuffer()');
diff --git a/test/parallel/test-buffer-tostring.js b/test/parallel/test-buffer-tostring.js
new file mode 100644
index 00000000000000..776b7c089224ed
--- /dev/null
+++ b/test/parallel/test-buffer-tostring.js
@@ -0,0 +1,25 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+
+// utf8, ucs2, ascii, latin1, utf16le
+const encodings = ['utf8', 'ucs2', 'ucs-2', 'ascii', 'latin1', 'binary',
+                   'utf16le', 'utf-16le'];
+
+encodings
+  .reduce((es, e) => es.concat(e, e.toUpperCase()), [])
+  .forEach((encoding) => {
+    assert.strictEqual(Buffer.from('foo', encoding).toString(encoding), 'foo');
+  });
+
+// base64
+['base64', 'BASE64'].forEach((encoding) => {
+  assert.strictEqual(Buffer.from('Zm9v', encoding).toString(encoding), 'Zm9v');
+});
+
+// hex
+['hex', 'HEX'].forEach((encoding) => {
+  assert.strictEqual(Buffer.from('666f6f', encoding).toString(encoding),
+                     '666f6f');
+});
diff --git a/test/parallel/test-buffer-write.js b/test/parallel/test-buffer-write.js
new file mode 100644
index 00000000000000..80c95dda4471e7
--- /dev/null
+++ b/test/parallel/test-buffer-write.js
@@ -0,0 +1,55 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+
+const outsideBounds = /^RangeError: Attempt to write outside buffer bounds$/;
+
+assert.throws(() => Buffer.alloc(9).write('foo', -1), outsideBounds);
+assert.throws(() => Buffer.alloc(9).write('foo', 10), outsideBounds);
+
+const resultMap = new Map([
+  ['utf8', Buffer.from([102, 111, 111, 0, 0, 0, 0, 0, 0])],
+  ['ucs2', Buffer.from([102, 0, 111, 0, 111, 0, 0, 0, 0])],
+  ['ascii', Buffer.from([102, 111, 111, 0, 0, 0, 0, 0, 0])],
+  ['latin1', Buffer.from([102, 111, 111, 0, 0, 0, 0, 0, 0])],
+  ['binary', Buffer.from([102, 111, 111, 0, 0, 0, 0, 0, 0])],
+  ['utf16le', Buffer.from([102, 0, 111, 0, 111, 0, 0, 0, 0])],
+  ['base64', Buffer.from([102, 111, 111, 0, 0, 0, 0, 0, 0])],
+  ['hex', Buffer.from([102, 111, 111, 0, 0, 0, 0, 0, 0])]
+]);
+
+// utf8, ucs2, ascii, latin1, utf16le
+const encodings = ['utf8', 'utf-8', 'ucs2', 'ucs-2', 'ascii', 'latin1',
+                   'binary', 'utf16le', 'utf-16le'];
+
+encodings
+  .reduce((es, e) => es.concat(e, e.toUpperCase()), [])
+  .forEach((encoding) => {
+    const buf = Buffer.alloc(9);
+    const len = Buffer.byteLength('foo', encoding);
+    assert.strictEqual(buf.write('foo', 0, len, encoding), len);
+
+    if (encoding.indexOf('-') !== -1)
+      encoding = encoding.replace('-', '');
+
+    assert.deepStrictEqual(buf, resultMap.get(encoding.toLowerCase()));
+  });
+
+// base64
+['base64', 'BASE64'].forEach((encoding) => {
+  const buf = Buffer.alloc(9);
+  const len = Buffer.byteLength('Zm9v', encoding);
+
+  assert.strictEqual(buf.write('Zm9v', 0, len, encoding), len);
+  assert.deepStrictEqual(buf, resultMap.get(encoding.toLowerCase()));
+});
+
+// hex
+['hex', 'HEX'].forEach((encoding) => {
+  const buf = Buffer.alloc(9);
+  const len = Buffer.byteLength('666f6f', encoding);
+
+  assert.strictEqual(buf.write('666f6f', 0, len, encoding), len);
+  assert.deepStrictEqual(buf, resultMap.get(encoding.toLowerCase()));
+});