test,doc: clarify `buf.indexOf(num)` input range

Hopefully clarify the behaviour of `buffer.indexOf()` and
`buffer.includes()` for numbers in that they will be
truncated to uint8s.

Add tests for that behaviour.

Fixes: https://github.com/nodejs/node/issues/7591
PR-URL: https://github.com/nodejs/node/pull/7611
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

2 files changed, 32 insertions, 0 deletions

diff --git a/test/parallel/test-buffer-includes.js b/test/parallel/test-buffer-includes.js
index 90f24c01f3..fe8f4fa69a 100644
--- a/test/parallel/test-buffer-includes.js
+++ b/test/parallel/test-buffer-includes.js
@@ -264,3 +264,19 @@ assert.throws(function() {
 assert.throws(function() {
   b.includes([]);
 });
+
+// test truncation of Number arguments to uint8
+{
+  const buf = Buffer.from('this is a test');
+  assert.ok(buf.includes(0x6973));
+  assert.ok(buf.includes(0x697320));
+  assert.ok(buf.includes(0x69732069));
+  assert.ok(buf.includes(0x697374657374));
+  assert.ok(buf.includes(0x69737374));
+  assert.ok(buf.includes(0x69737465));
+  assert.ok(buf.includes(0x69737465));
+  assert.ok(buf.includes(-140));
+  assert.ok(buf.includes(-152));
+  assert.ok(!buf.includes(0xff));
+  assert.ok(!buf.includes(0xffff));
+}
diff --git a/test/parallel/test-buffer-indexof.js b/test/parallel/test-buffer-indexof.js
index 3d5620aa81..59e969c315 100644
--- a/test/parallel/test-buffer-indexof.js
+++ b/test/parallel/test-buffer-indexof.js
@@ -470,3 +470,19 @@ pattern = reallyLong.slice(0, 1000000);  // First 1/5th.
 assert.equal(3932160, reallyLong.lastIndexOf(pattern));
 pattern = reallyLong.slice(0, 2000000);  // first 2/5ths.
 assert.equal(0, reallyLong.lastIndexOf(pattern));
+
+// test truncation of Number arguments to uint8
+{
+  const buf = Buffer.from('this is a test');
+  assert.strictEqual(buf.indexOf(0x6973), 3);
+  assert.strictEqual(buf.indexOf(0x697320), 4);
+  assert.strictEqual(buf.indexOf(0x69732069), 2);
+  assert.strictEqual(buf.indexOf(0x697374657374), 0);
+  assert.strictEqual(buf.indexOf(0x69737374), 0);
+  assert.strictEqual(buf.indexOf(0x69737465), 11);
+  assert.strictEqual(buf.indexOf(0x69737465), 11);
+  assert.strictEqual(buf.indexOf(-140), 0);
+  assert.strictEqual(buf.indexOf(-152), 1);
+  assert.strictEqual(buf.indexOf(0xff), -1);
+  assert.strictEqual(buf.indexOf(0xffff), -1);
+}