test: increase coverage of string-decoder

Make use of Arrow Function.
Add normalizeencoding's test.
normalizeEncoding:
https://github.com/nodejs/node/blob/master/lib/string_decoder.js#L9

PR-URL: https://github.com/nodejs/node/pull/10863
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 10 insertions, 2 deletions

diff --git a/test/parallel/test-string-decoder.js b/test/parallel/test-string-decoder.js
index 77ffbfcc73..a8fdb999a0 100644
--- a/test/parallel/test-string-decoder.js
+++ b/test/parallel/test-string-decoder.js
@@ -104,6 +104,14 @@ assert.strictEqual(decoder.write(Buffer.from('3DD8', 'hex')), '');
 assert.strictEqual(decoder.write(Buffer.from('4D', 'hex')), '');
 assert.strictEqual(decoder.end(), '\ud83d');
 
+assert.throws(() => {
+  new StringDecoder(1);
+}, /^Error: Unknown encoding: 1$/);
+
+assert.throws(() => {
+  new StringDecoder('test');
+}, /^Error: Unknown encoding: test$/);
+
 // test verifies that StringDecoder will correctly decode the given input
 // buffer with the given encoding to the expected output. It will attempt all
 // possible ways to write() the input buffer, see writeSequences(). The
@@ -116,10 +124,10 @@ function test(encoding, input, expected, singleSequence) {
   } else {
     sequences = [singleSequence];
   }
-  sequences.forEach(function(sequence) {
+  sequences.forEach((sequence) => {
     const decoder = new StringDecoder(encoding);
     let output = '';
-    sequence.forEach(function(write) {
+    sequence.forEach((write) => {
       output += decoder.write(input.slice(write[0], write[1]));
     });
     output += decoder.end();