test: fix test-buffer-tostring-range on allocation failure

If the test cannot allocate a buffer over 4GB, there is no point
continue testing toString() on it.
This also split the test case to a different file for clarity and
reduce interference with other cases.
PR-URL: #58416Fixes: #56726
Reviewed-By: LiviaMedeiros <livia@cirno.name>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Stefan Stojanovic <stefan.stojanovic@janeasystems.com>

Author: joyeecheung

test/parallel/test-buffer-tostring-4gb.js

@@ -0,0 +1,20 @@
+'use strict';
+
+// This tests that Buffer.prototype.toString() works with buffers over 4GB.
+constcommon=require('../common');
+
+// Must not throw when start and end are within kMaxLength
+// Cannot test on 32bit machine as we are testing the case
+// when start and end are above the threshold
+common.skipIf32Bits();
+constthreshold=0xFFFFFFFF;// 2^32 - 1
+letlargeBuffer;
+try{
+largeBuffer=Buffer.alloc(threshold+20);
+}catch(e){
+if(e.code==='ERR_MEMORY_ALLOCATION_FAILED'||/Arraybufferallocationfailed/.test(e.message)){
+common.skip('insufficient space for Buffer.alloc');
+}
+throwe;
+}
+largeBuffer.toString('utf8',threshold,threshold+20);

test/parallel/test-buffer-tostring-range.js

@@ -1,6 +1,6 @@
 'use strict';
 
-constcommon=require('../common');
+require('../common');
 constassert=require('assert');
 
 constrangeBuffer=Buffer.from('abc');
@@ -98,11 +98,3 @@ assert.throws(() => {
 name: 'TypeError',
 message: 'Unknown encoding: null'
 });
-
-// Must not throw when start and end are within kMaxLength
-// Cannot test on 32bit machine as we are testing the case
-// when start and end are above the threshold
-common.skipIf32Bits();
-constthreshold=0xFFFFFFFF;
-constlargeBuffer=Buffer.alloc(threshold+20);
-largeBuffer.toString('utf8',threshold,threshold+20);