fix(core): handle member with undefined value in valueOf

Author: kylef

packages/api-elements/CHANGELOG.md

@@ -1,5 +1,12 @@
 # API Elements (JavaScript) CHANGELOG
 
+## 0.2.5 (2020-06-13)
+
+### Bug Fixes
+
+- Prevent `valueOf` from throwing an error while handling an object element
+  which contains a member element which does not include a value.
+
 ## 0.2.4 (2020-04-20)
 
 ### Enhancements

packages/api-elements/lib/define-value-of.js

@@ -108,6 +108,10 @@ function trivialValue(e) {
 }
 
 function mapValue(e, options, f, elements) {
+  if (e === undefined) {
+    return e;
+  }
+
   const opts = updateTypeAttributes(e, options);
   if (e.content && (!isPlural(e) || !e.isEmpty)) {
     const result = f(e, opts, elements, 'content');

packages/api-elements/package.json

@@ -1,6 +1,6 @@
 {
   "name": "api-elements",
-  "version": "0.2.4",
+  "version": "0.2.5",
   "description": "API Elements JavaScript",
   "author": "Apiary.io <support@apiary.io>",
   "license": "MIT",

packages/api-elements/test/value-of-test.js

@@ -6,6 +6,7 @@ const namespace = new Namespace();
 const { Element } = namespace;
 const ArrayElement = namespace.elements.Array;
 const ObjectElement = namespace.elements.Object;
+const MemberElement = namespace.elements.Member;
 const BooleanElement = namespace.elements.Boolean;
 const EnumElement = namespace.elements.Enum;
 const NullElement = namespace.elements.Null;
@@ -845,6 +846,14 @@ describe('valueOf ObjectElement', () => {
     expect(value).to.deep.equal(undefined);
   });
 
+  it('skips property without value', () => {
+    const element = new ObjectElement({ company: 'Oracle' });
+    element.push(new MemberElement('name'));
+    const value = element.valueOf();
+
+    expect(value).to.deep.equal({ company: 'Oracle' });
+  });
+
   it('returns undefined when fixed and with item without value', () => {
     const element = new ObjectElement({
       a: 8, b: 4, c: new EnumElement(), d: 42,