assert: Check typed array view type in deepEqual

Do not convert typed arrays to `Buffer` for deepEqual since
their values may not be accurately represented by 8-bit ints.
Instead perform binary comparison of underlying `ArrayBuffer`s,
but only when the array types match.
Never apply any kind of optimization for floating-point typed
arrays since bit pattern equality is not the right kind of check
for them.
PR-URL: #5910
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Fixes: #5907

Author: addaleax

lib/assert.js

@@ -29,6 +29,7 @@ const compare = process.binding('buffer').compare;
 constutil=require('util');
 constBuffer=require('buffer').Buffer;
 constpSlice=Array.prototype.slice;
+constpToString=(obj)=>Object.prototype.toString.call(obj);
 
 // 1. The assert module provides functions that throw
 // AssertionError's when particular conditions are not met. The
@@ -170,10 +171,18 @@ function _deepEqual(actual, expected, strict) {
 (expected===null||typeofexpected!=='object')){
 returnstrict ? actual===expected : actual==expected;
 
-// If both values are instances of typed arrays, wrap them in
-// a Buffer each to increase performance
-}elseif(ArrayBuffer.isView(actual)&&ArrayBuffer.isView(expected)){
-returncompare(newBuffer(actual),newBuffer(expected))===0;
+// If both values are instances of typed arrays, wrap their underlying
+// ArrayBuffers in a Buffer each to increase performance
+// This optimization requires the arrays to have the same type as checked by
+// Object.prototype.toString (aka pToString). Never perform binary
+// comparisons for Float*Arrays, though, since e.g. +0 === -0 but their
+// bit patterns are not identical.
+}elseif(ArrayBuffer.isView(actual)&&ArrayBuffer.isView(expected)&&
+pToString(actual)===pToString(expected)&&
+!(actualinstanceofFloat32Array||
+actualinstanceofFloat64Array)){
+returncompare(newBuffer(actual.buffer),
+newBuffer(expected.buffer))===0;
 
 // 7.5 For all other Object pairs, including Array objects, equivalence is
 // determined by having the same number of owned properties (as verified

test/parallel/test-assert-typedarray-deepequal.js

@@ -20,13 +20,25 @@ const equalArrayPairs = [
 [newInt16Array(1e5),newInt16Array(1e5)],
 [newInt32Array(1e5),newInt32Array(1e5)],
 [newFloat32Array(1e5),newFloat32Array(1e5)],
-[newFloat64Array(1e5),newFloat64Array(1e5)]
+[newFloat64Array(1e5),newFloat64Array(1e5)],
+[newInt16Array(256),newUint16Array(256)],
+[newInt16Array([256]),newUint16Array([256])],
+[newFloat32Array([+0.0]),newFloat32Array([-0.0])],
+[newFloat64Array([+0.0]),newFloat32Array([-0.0])],
+[newFloat64Array([+0.0]),newFloat64Array([-0.0])]
 ];
 
 constnotEqualArrayPairs=[
 [newUint8Array(2),newUint8Array(3)],
 [newUint8Array([1,2,3]),newUint8Array([4,5,6])],
-[newUint8ClampedArray([300,2,3]),newUint8Array([300,2,3])]
+[newUint8ClampedArray([300,2,3]),newUint8Array([300,2,3])],
+[newUint16Array([2]),newUint16Array([3])],
+[newUint16Array([0]),newUint16Array([256])],
+[newInt16Array([0]),newUint16Array([256])],
+[newInt16Array([-256]),newUint16Array([0xff00])],// same bits
+[newInt32Array([-256]),newUint32Array([0xffffff00])],// ditto
+[newFloat32Array([0.1]),newFloat32Array([0.0])],
+[newFloat64Array([0.1]),newFloat64Array([0.0])]
 ];
 
 equalArrayPairs.forEach((arrayPair)=>{