util: add null prototype support for date

lib/internal/util/inspect.js

@@ -77,6 +77,7 @@ function uncurryThis(func) {
 const propertyIsEnumerable = uncurryThis(Object.prototype.propertyIsEnumerable);
 const regExpToString = uncurryThis(RegExp.prototype.toString);
 const dateToISOString = uncurryThis(Date.prototype.toISOString);
+const dateToString = uncurryThis(Date.prototype.toString);
 const errorToString = uncurryThis(Error.prototype.toString);
 
 const bigIntValueOf = uncurryThis(BigInt.prototype.valueOf);
@@ -646,12 +647,15 @@ function formatRaw(ctx, value, recurseTimes, typedArray) {
         return ctx.stylize(base, 'regexp');
     } else if (isDate(value)) {
       // Make dates with properties first say the date
+      base = Number.isNaN(dateGetTime(value)) ?
+        dateToString(value) :
+        dateToISOString(value);
+      const prefix = getPrefix(constructor, tag, 'Date');
+      if (prefix !== 'Date ')
+        base = `${prefix}${base}`;
       if (keys.length === 0) {
-        if (Number.isNaN(dateGetTime(value)))
-          return ctx.stylize(String(value), 'date');
-        return ctx.stylize(dateToISOString(value), 'date');
+        return ctx.stylize(base, 'date');
       }
-      base = dateToISOString(value);
     } else if (isError(value)) {
       // Make error with message first say the error.
       base = formatError(value);

test/parallel/test-assert-deep.js

@@ -117,16 +117,16 @@ assert.throws(
   {
     code: 'ERR_ASSERTION',
     message: `${defaultMsgStartFull}\n\n` +
-             '+ 2016-01-01T00:00:00.000Z\n- 2016-01-01T00:00:00.000Z {\n' +
-             "-   '0': '1'\n- }"
+             '+ 2016-01-01T00:00:00.000Z\n- MyDate 2016-01-01T00:00:00.000Z' +
+             " {\n-   '0': '1'\n- }"
   }
 );
 assert.throws(
   () => assert.deepStrictEqual(date2, date),
   {
     code: 'ERR_ASSERTION',
     message: `${defaultMsgStartFull}\n\n` +
-             '+ 2016-01-01T00:00:00.000Z {\n' +
+             '+ MyDate 2016-01-01T00:00:00.000Z {\n' +
              "+   '0': '1'\n+ }\n- 2016-01-01T00:00:00.000Z"
   }
 );

test/parallel/test-util-inspect.js

@@ -1663,7 +1663,9 @@ assert.strictEqual(util.inspect('"\'${a}'), "'\"\\'${a}'");
      'byteOffset: undefined,\n  buffer: undefined }'],
   [new SharedArrayBuffer(2), '[SharedArrayBuffer: null prototype] ' +
      '{ [Uint8Contents]: <00 00>, byteLength: undefined }'],
-  [/foobar/, '[RegExp: null prototype] /foobar/']
+  [/foobar/, '[RegExp: null prototype] /foobar/'],
+  [new Date('Sun, 14 Feb 2010 11:48:40 GMT'),
+   '[Date: null prototype] 2010-02-14T11:48:40.000Z']
 ].forEach(([value, expected]) => {
   assert.strictEqual(
     util.inspect(Object.setPrototypeOf(value, null)),
@@ -1707,6 +1709,50 @@ assert.strictEqual(util.inspect('"\'${a}'), "'\"\\'${a}'");
   assert(/\[Symbol\(foo\)]: 'yeah'/.test(res), res);
 });
 
+// Date null prototype checks
+{
+  class CustomDate extends Date {
+  }
+
+  const date = new CustomDate('Sun, 14 Feb 2010 11:48:40 GMT');
+  assert.strictEqual(util.inspect(date), 'CustomDate 2010-02-14T11:48:40.000Z');
+
+  // add properties
+  date.foo = 'bar';
+  assert.strictEqual(util.inspect(date),
+                     '{ CustomDate 2010-02-14T11:48:40.000Z foo: \'bar\' }');
+
+  // check for null prototype
+  Object.setPrototypeOf(date, null);
+  assert.strictEqual(util.inspect(date),
+                     '{ [Date: null prototype] 2010-02-14T11:48:40.000Z' +
+                     ' foo: \'bar\' }');
+
+  const anotherDate = new CustomDate('Sun, 14 Feb 2010 11:48:40 GMT');
+  Object.setPrototypeOf(anotherDate, null);
+  assert.strictEqual(util.inspect(anotherDate),
+                     '[Date: null prototype] 2010-02-14T11:48:40.000Z');
+}
+
+// Check for invalid dates and null prototype
+{
+  class CustomDate extends Date {
+  }
+
+  const date = new CustomDate('invalid_date');
+  assert.strictEqual(util.inspect(date), 'CustomDate Invalid Date');
+
+  // add properties
+  date.foo = 'bar';
+  assert.strictEqual(util.inspect(date),
+                     '{ CustomDate Invalid Date foo: \'bar\' }');
+
+  // check for null prototype
+  Object.setPrototypeOf(date, null);
+  assert.strictEqual(util.inspect(date),
+                     '{ [Date: null prototype] Invalid Date foo: \'bar\' }');
+}
+
 assert.strictEqual(inspect(1n), '1n');
 assert.strictEqual(inspect(Object(-1n)), '[BigInt: -1n]');
 assert.strictEqual(inspect(Object(13n)), '[BigInt: 13n]');