test: improve buffer coverage

PR-URL: nodejs#38538
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Khaidi Chu <i@2333.moe>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-buffer-copy.js

@@ -30,6 +30,17 @@ let cntr = 0;
   }
 }
 
+{
+  // Floats will be converted to integers via `Math.floor`
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = b.copy(c, 0, 0, 512.5);
+  assert.strictEqual(copied, 512);
+  for (let i = 0; i < c.length; i++) {
+    assert.strictEqual(c[i], b[i]);
+  }
+}
+
 {
   // Copy c into b, without specifying sourceEnd
   b.fill(++cntr);
@@ -52,6 +63,17 @@ let cntr = 0;
   }
 }
 
+{
+  // Copied source range greater than source length
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = c.copy(b, 0, 0, c.length + 1);
+  assert.strictEqual(copied, c.length);
+  for (let i = 0; i < c.length; i++) {
+    assert.strictEqual(b[i], c[i]);
+  }
+}
+
 {
   // Copy longer buffer b to shorter c without targetStart
   b.fill(++cntr);
@@ -107,6 +129,26 @@ bb.fill('hello crazy world');
 // Try to copy from before the beginning of b. Should not throw.
 b.copy(c, 0, 100, 10);
 
+// Throw with invalid source type
+assert.throws(
+  () => Buffer.prototype.copy.call(0),
+  {
+    code: 'ERR_INVALID_ARG_TYPE',
+    name: 'TypeError',
+  }
+);
+
+// Copy throws at negative targetStart
+assert.throws(
+  () => Buffer.allocUnsafe(5).copy(Buffer.allocUnsafe(5), -1, 0),
+  {
+    code: 'ERR_OUT_OF_RANGE',
+    name: 'RangeError',
+    message: 'The value of "targetStart" is out of range. ' +
+             'It must be >= 0. Received -1'
+  }
+);
+
 // Copy throws at negative sourceStart
 assert.throws(
   () => Buffer.allocUnsafe(5).copy(Buffer.allocUnsafe(5), 0, -1),

test/parallel/test-buffer-indexof.js

@@ -180,15 +180,18 @@ assert.strictEqual(Buffer.from('aaaa0').indexOf('30', 'hex'), 4);
 assert.strictEqual(Buffer.from('aaaa00a').indexOf('3030', 'hex'), 4);
 
 {
-  // test usc2 encoding
-  const twoByteString = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'ucs2');
-
-  assert.strictEqual(twoByteString.indexOf('\u0395', 4, 'ucs2'), 8);
-  assert.strictEqual(twoByteString.indexOf('\u03a3', -4, 'ucs2'), 6);
-  assert.strictEqual(twoByteString.indexOf('\u03a3', -6, 'ucs2'), 4);
-  assert.strictEqual(twoByteString.indexOf(
-    Buffer.from('\u03a3', 'ucs2'), -6, 'ucs2'), 4);
-  assert.strictEqual(-1, twoByteString.indexOf('\u03a3', -2, 'ucs2'));
+  // Test usc2 and utf16le encoding
+  ['ucs2', 'utf16le'].forEach((encoding) => {
+    const twoByteString = Buffer.from(
+      '\u039a\u0391\u03a3\u03a3\u0395', encoding);
+
+    assert.strictEqual(twoByteString.indexOf('\u0395', 4, encoding), 8);
+    assert.strictEqual(twoByteString.indexOf('\u03a3', -4, encoding), 6);
+    assert.strictEqual(twoByteString.indexOf('\u03a3', -6, encoding), 4);
+    assert.strictEqual(twoByteString.indexOf(
+      Buffer.from('\u03a3', encoding), -6, encoding), 4);
+    assert.strictEqual(-1, twoByteString.indexOf('\u03a3', -2, encoding));
+  });
 }
 
 const mixedByteStringUcs2 =