test: increase coverage for buffer.js

test/parallel/test-buffer-arraybuffer.js

@@ -105,3 +105,41 @@ b.writeDoubleBE(11.11, 0, true);
     return true;
   });
 }
+
+{
+  // If byteOffset is not numeric, it defaults to 0.
+  const ab = new ArrayBuffer(10);
+  const expected = Buffer.from(ab, 0);
+  assert.deepStrictEqual(Buffer.from(ab, 'fhqwhgads'), expected);
+  assert.deepStrictEqual(Buffer.from(ab, NaN), expected);
+  assert.deepStrictEqual(Buffer.from(ab, {}), expected);
+  assert.deepStrictEqual(Buffer.from(ab, []), expected);
+
+  // If byteOffset can be converted to a number, it will be.
+  assert.deepStrictEqual(Buffer.from(ab, [1]), Buffer.from(ab, 1));
+
+  // If byteOffset is Infinity, throw.
+  assert.throws(
+    () => { Buffer.from(ab, Infinity); },
+    /^RangeError: 'offset' is out of bounds$/
+  );
+}
+
+{
+  // If length is not numeric, it defaults to 0.
+  const ab = new ArrayBuffer(10);
+  const expected = Buffer.from(ab, 0, 0);
+  assert.deepStrictEqual(Buffer.from(ab, 0, 'fhqwhgads'), expected);
+  assert.deepStrictEqual(Buffer.from(ab, 0, NaN), expected);
+  assert.deepStrictEqual(Buffer.from(ab, 0, {}), expected);
+  assert.deepStrictEqual(Buffer.from(ab, 0, []), expected);
+
+  // If length can be converted to a number, it will be.
+  assert.deepStrictEqual(Buffer.from(ab, 0, [1]), Buffer.from(ab, 0, 1));
+
+  //If length is Infinity, throw.
+  assert.throws(
+    () => { Buffer.from(ab, 0, Infinity); },
+    /^RangeError: 'length' is out of bounds$/
+  );
+}