test: refactor test:demo script into demo/*/test.sh

demo/reactjs/src/engine.ts

@@ -0,0 +1,11 @@
+import { Liquid } from 'liquidjs';
+
+export const engine = new Liquid({
+    root: 'views/',
+    extname: '.liquid'     // the extname used for layouts/includes, defaults 
+});
+
+engine.registerFilter('image', d => {
+  let img = `<img src="${d}" class="App-logo" alt="logo"></img>`;  
+  return img 
+})