Fix select value not marking option as selected

Author: marvinhagemeister

src/index.js

@@ -149,6 +149,17 @@ function renderToString(vnode, context, opts, inner, isSvgMode) {
 						continue;
 					}
 				}
+
+				if (name==='value') {
+					if (nodeName==='select') {
+						context = assign({}, context);
+						context.__preactSelect__ = v;
+						continue;
+					}
+					else if (context.__preactSelect__!==undefined && nodeName==='option' && context.__preactSelect__===v) {
+						s += ` selected`;
+					}
+				}
 				s += ` ${name}="${encodeEntities(v)}"`;
 			}
 		}

test/render.js

@@ -730,4 +730,42 @@ describe('render', () => {
 			expect(called).to.equal(false);
 		});
 	});
+
+	it('should render select value on option', () => {
+		let res = render(
+			<select value="B">
+				<option value="A">A</option>
+				<option value="B">B</option>
+			</select>
+		);
+		expect(res).to.equal('<select><option value="A">A</option><option selected value="B">B</option></select>');
+	});
+
+	it('should not leak select value into parent context', () => {
+		let fn = spy();
+		function Bar(_, context) {
+			fn(context);
+			return null;
+		}
+
+		class Foo extends Component {
+			getChildContext() {
+				return { foo: 'bar' };
+			}
+
+			render() {
+				return (
+					<div>
+						<select value="A">
+							<option value="A">A</option>
+						</select>
+						<Bar />
+					</div>
+				);
+			}
+		}
+
+		render(<Foo />);
+		expect(fn.args[0][0]).to.deep.equal({ foo: 'bar' });
+	});
 });