add test file to testing mosaic package will remove this later

IDAES-UI/src/components/flowsheet_main_component/flex_layout_test/flex_layout_test.tsx

@@ -0,0 +1,33 @@
+import { Mosaic } from 'react-mosaic-component';
+import 'react-mosaic-component/react-mosaic-component.css';
+
+import '@blueprintjs/core/lib/css/blueprint.css';
+import '@blueprintjs/icons/lib/css/blueprint-icons.css';
+
+
+const ELEMENT_MAP: { [viewId: string]: JSX.Element } = {
+    flowsheetWindow: <div>Flowsheet container</div>,
+    b: <div>Top Right Window</div>,
+    c: <div>Bottom Right Window</div>,
+  };
+
+const MosaicApp = () => (
+    <div id="app">
+        <Mosaic
+            renderTile={(id) => ELEMENT_MAP[id]}
+            initialValue={{
+                direction: 'row',
+                first: 'flowsheetWindow',
+                second: {
+                    direction: 'column',
+                    first: 'b',
+                    second: 'c',
+                },
+                splitPercentage: 40,
+            }}
+        />
+    </div>
+  );
+
+
+export default MosaicApp