added test for screenshot component (#70)

nightwatch/components/screenshot.spec.tsx

@@ -0,0 +1,26 @@
+import GlobalStyles from '../../src/components/GlobalStyles';
+import Screenshot from '../../src/components/Screenshot';
+
+export default {
+    title: "ScreenshotComponent",
+    component: Screenshot
+};
+
+
+export const ScreenshotComponent = () => (
+    <>
+        <GlobalStyles />
+        <Screenshot />
+    </>
+);
+
+ScreenshotComponent.test = async (browser,{component}) => {
+
+    browser.expect(component).to.be.present.before(1000);
+
+
+    browser.getCssProperty(component, 'height', function(result) {
+        this.assert.ok(result.value !== '0px', 'Check if Screenshot height is not zero');
+    });
+
+};