assert: handle sparse arrays in deepStrictEqual

BridgeAR · BridgeAR · commit 4381100371b6 · 2017-08-28T23:19:03.000-03:00
Detect sparse array ends and add a fail early path for unequal array length. PR-URL: #15027 Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Tobias Nießen <tniessen@tnie.de>
diff --git a/lib/assert.js b/lib/assert.js
@@ -180,7 +180,14 @@ function strictDeepEqual(actual, expected) {
   if (Object.getPrototypeOf(actual) !== Object.getPrototypeOf(expected)) {
     return false;
   }
-  if (isObjectOrArrayTag(actualTag)) {
+  if (actualTag === '[object Array]') {
+    // Check for sparse arrays and general fast path
+    if (actual.length !== expected.length)
+      return false;
+    // Skip testing the part below and continue in the callee function.
+    return;
+  }
+  if (actualTag === '[object Object]') {
     // Skip testing the part below and continue in the callee function.
     return;
   }
diff --git a/test/parallel/test-assert-deep.js b/test/parallel/test-assert-deep.js
@@ -466,4 +466,7 @@ assertOnlyDeepEqual(
   assertDeepAndStrictEqual(m3, m4);
 }
 
+assertDeepAndStrictEqual([1, , , 3], [1, , , 3]);
+assertOnlyDeepEqual([1, , , 3], [1, , , 3, , , ]);
+
 /* eslint-enable */

Original file line number	Diff line number	Diff line change
`@@ -466,4 +466,7 @@ assertOnlyDeepEqual(`
`466`	`466`	`assertDeepAndStrictEqual(m3, m4);`
`467`	`467`	`}`
`468`	`468`
	`469`	`+assertDeepAndStrictEqual([1, , , 3], [1, , , 3]);`
	`470`	`+assertOnlyDeepEqual([1, , , 3], [1, , , 3, , , ]);`
	`471`	`+`
`469`	`472`	`/* eslint-enable */`