test: test cases for surrogate to usv string

Added test cases to check surrogate code points to usv string conversion
in stream consumers and text decoder

Fixes: #39804

test/parallel/test-stream-consumers.js

@@ -13,6 +13,7 @@ const {
 } = require('stream/consumers');
 
 const {
+  Readable,
   PassThrough
 } = require('stream');
 
@@ -74,15 +75,16 @@ const kArrayBuffer =
 }
 
 {
-  const passthrough = new PassThrough();
+  const readable = new Readable({
+    read() {}
+  });
 
-  text(passthrough).then(common.mustCall(async (str) => {
-    assert.strictEqual(str.length, 11);
-    assert.deepStrictEqual(str, 'hellothere\ufffd');
-  }));
+  text(readable).then((data) => {
+    assert.deepStrictEqual(data, 'foo\ufffd\ufffd\ufffd');
+  });
 
-  passthrough.write('hello');
-  setTimeout(() => passthrough.end('there\ud801'), 10);
+  readable.push(new Uint8Array([0x66, 0x6f, 0x6f, 0xed, 0xa0, 0x80]));
+  readable.push(null);
 }
 
 {

test/parallel/test-whatwg-encoding-custom-textdecoder.js

@@ -195,14 +195,7 @@ if (common.hasIntl) {
 // Test TextDecoder for surrogate code points
 {
   const decoder = new TextDecoder();
-  const chunk = Buffer.from([0x66, 0x6f, 0x6f, 0xed, 0xa0, 0x80]);
+  const chunk = new Uint8Array([0x66, 0x6f, 0x6f, 0xed]);
   const str = decoder.decode(chunk);
-  assert.strictEqual(str, 'foo\ufffd\ufffd\ufffd');
-}
-
-{
-  const decoder = new TextDecoder();
-  const chunk = Buffer.from('\ud807');
-  const str = decoder.decode(chunk);
-  assert.strictEqual(str, '\ufffd');
+  assert.strictEqual(str, 'foo\ufffd');
 }