errors: make code and name properties settable

For internal errors, make `code` and `name` settable while keeping them
non-own properties by default.

PR-URL: https://github.com/nodejs/node/pull/15694
Fixes: https://github.com/nodejs/node/issues/15658
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

lib/internal/errors.js

@@ -11,9 +11,8 @@
 const kCode = Symbol('code');
 const messages = new Map();
 
-const {
+const { kMaxLength } = process.binding('buffer');
-  kMaxLength
+const { defineProperty } = Object;
-} = process.binding('buffer');
 
 // Lazily loaded
 var util = null;
@@ -22,11 +21,36 @@ function makeNodeError(Base) {
   return class NodeError extends Base {
     constructor(key, ...args) {
       super(message(key, args));
-      this[kCode] = this.code = key;
+      defineProperty(this, kCode, {
-      Object.defineProperty(this, 'name', {
         configurable: true,
         enumerable: false,
-        value: `${super.name} [${this[kCode]}]`,
+        value: key,
+        writable: true
+      });
+    }
+
+    get name() {
+      return `${super.name} [${this[kCode]}]`;
+    }
+
+    set name(value) {
+      defineProperty(this, 'name', {
+        configurable: true,
+        enumerable: true,
+        value,
+        writable: true
+      });
+    }
+
+    get code() {
+      return this[kCode];
+    }
+
+    set code(value) {
+      defineProperty(this, 'code', {
+        configurable: true,
+        enumerable: true,
+        value,
         writable: true
       });
     }

test/parallel/test-internal-errors.js

@@ -307,38 +307,52 @@ assert.strictEqual(
 {
   const myError = new errors.Error('ERR_TLS_HANDSHAKE_TIMEOUT');
   assert.strictEqual(myError.code, 'ERR_TLS_HANDSHAKE_TIMEOUT');
+  assert.strictEqual(myError.hasOwnProperty('code'), false);
+  assert.strictEqual(myError.hasOwnProperty('name'), false);
+  assert.deepStrictEqual(Object.keys(myError), []);
   const initialName = myError.name;
   myError.code = 'FHQWHGADS';
   assert.strictEqual(myError.code, 'FHQWHGADS');
   assert.strictEqual(myError.name, initialName);
+  assert.deepStrictEqual(Object.keys(myError), ['code']);
   assert.ok(myError.name.includes('ERR_TLS_HANDSHAKE_TIMEOUT'));
   assert.ok(!myError.name.includes('FHQWHGADS'));
 }
 
-// Test that `name` and `message` are mutable and that changing them alters 
+// Test that `name` is mutable and that changing it alters `toString()` but not
-// `toString()` but not `console.log()` results, which is the behavior of
+// `console.log()` results, which is the behavior of `Error` objects in the
-// `Error` objects in the browser.
+// browser. Note that `name` becomes enumerable after being assigned.
 {
-  function test(prop) {
+  const myError = new errors.Error('ERR_TLS_HANDSHAKE_TIMEOUT');
-    let initialConsoleLog = '';
+  assert.deepStrictEqual(Object.keys(myError), []);
-    common.hijackStdout((data) => { initialConsoleLog += data; });
+  const initialToString = myError.toString();
-    const myError = new errors.Error('ERR_TLS_HANDSHAKE_TIMEOUT');
-    const initialToString = myError.toString();
-    console.log(myError);
-    assert.notStrictEqual(initialConsoleLog, '');
 
-    common.restoreStdout();
+  myError.name = 'Fhqwhgads';
-
+  assert.deepStrictEqual(Object.keys(myError), ['name']);
-    let subsequentConsoleLog = '';
+  assert.notStrictEqual(myError.toString(), initialToString);
-    common.hijackStdout((data) => { subsequentConsoleLog += data; });
+}
-    myError[prop] = 'Fhqwhgads';
+
-    assert.notStrictEqual(myError.toString(), initialToString);
+// Test that `message` is mutable and that changing it alters `toString()` but
-    console.log(myError);
+// not `console.log()` results, which is the behavior of `Error` objects in the
-    assert.strictEqual(subsequentConsoleLog, initialConsoleLog);
+// browser. Note that `message` remains non-enumerable after being assigned.
-
+{
-    common.restoreStdout();
+  let initialConsoleLog = '';
-  }
+  common.hijackStdout((data) => { initialConsoleLog += data; });
-
+  const myError = new errors.Error('ERR_TLS_HANDSHAKE_TIMEOUT');
-  test('name');
+  assert.deepStrictEqual(Object.keys(myError), []);
-  test('message');
+  const initialToString = myError.toString();
+  console.log(myError);
+  assert.notStrictEqual(initialConsoleLog, '');
+
+  common.restoreStdout();
+
+  let subsequentConsoleLog = '';
+  common.hijackStdout((data) => { subsequentConsoleLog += data; });
+  myError.message = 'Fhqwhgads';
+  assert.deepStrictEqual(Object.keys(myError), []);
+  assert.notStrictEqual(myError.toString(), initialToString);
+  console.log(myError);
+  assert.strictEqual(subsequentConsoleLog, initialConsoleLog);
+
+  common.restoreStdout();
 }