test: increase coverage of buffer

PR-URL: #11312
Backport-of: #11122
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>

test/parallel/test-buffer-compare-offset.js

@@ -11,6 +11,7 @@ assert.strictEqual(-1, a.compare(b));
 // Equivalent to a.compare(b).
 assert.strictEqual(-1, a.compare(b, 0));
 assert.strictEqual(-1, a.compare(b, '0'));
+assert.strictEqual(-1, a.compare(b, undefined));
 
 // Equivalent to a.compare(b).
 assert.strictEqual(-1, a.compare(b, 0, undefined, 0));
@@ -63,5 +64,6 @@ assert.throws(() => a.compare(b, 0, 1, 0, 100), oor);
 assert.throws(() => a.compare(b, -1), oor);
 assert.throws(() => a.compare(b, 0, '0xff'), oor);
 assert.throws(() => a.compare(b, 0, Infinity), oor);
+assert.throws(() => a.compare(b, 0, 1, -1), oor);
 assert.throws(() => a.compare(b, -Infinity, Infinity), oor);
 assert.throws(() => a.compare(), /Argument must be a Buffer/);

test/parallel/test-buffer-write-noassert.js

@@ -20,6 +20,17 @@ function write(funx, args, result, res) {
     );
   }
 
+  {
+    const error = /Int/.test(funx) ?
+      /^TypeError: "buffer" argument must be a Buffer instance$/ :
+      /^TypeError: argument should be a Buffer$/;
+
+    assert.throws(
+      () => Buffer.alloc(9)[funx].apply(new Uint32Array(1), args),
+      error
+    );
+  }
+
   {
     const buf2 = Buffer.alloc(9);
     assert.strictEqual(buf2[funx](...args, true), result);