[Fix] check extra properties on regexps

See #40 (comment)

Author: ljharb

index.js

@@ -290,8 +290,8 @@ function objEquiv(a, b, opts, channel) {
   var aIsRegex = isRegex(a);
   var bIsRegex = isRegex(b);
   if (aIsRegex !== bIsRegex) { return false; }
-  if (aIsRegex || bIsRegex) {
-    return a.source === b.source && flags(a) === flags(b);
+  if ((aIsRegex || bIsRegex) && (a.source !== b.source || flags(a) !== flags(b))) {
+    return false;
   }
 
   var aIsDate = isDate(a);

test/cmp.js

@@ -261,6 +261,17 @@ test('Dates', function (t) {
     st.end();
   });
 
+  var a = new Date('2000');
+  var b = new Date('2000');
+  b.foo = true;
+  t.deepEqualTest(
+    a,
+    b,
+    'two identical Dates, one with an extra property',
+    false,
+    false
+  );
+
   t.end();
 });
 
@@ -294,6 +305,22 @@ test('buffers', { skip: typeof Buffer !== 'function' }, function (t) {
   t.end();
 });
 
+test('Arrays', function (t) {
+  var a = [];
+  var b = [];
+  b.foo = true;
+
+  t.deepEqualTest(
+    a,
+    b,
+    'two identical arrays, one with an extra property',
+    false,
+    false
+  );
+
+  t.end();
+});
+
 test('booleans and arrays', function (t) {
   t.deepEqualTest(
     true,
@@ -525,6 +552,17 @@ test('regexen', function (t) {
     st.end();
   });
 
+  var a = /abc/gi;
+  var b = /abc/gi;
+  b.foo = true;
+  t.deepEqualTest(
+    a,
+    b,
+    'two identical regexes, one with an extra property',
+    false,
+    false
+  );
+
   t.end();
 });