Update

components/__tests__/ThemedText-test.tsx

@@ -0,0 +1,12 @@
+import * as React from 'react';
+import renderer from 'react-test-renderer';
+
+import {ThemedText} from '../ThemedText';
+
+it(`renders correctly`, () => {
+  const tree = renderer
+    .create(<ThemedText>Snapshot test!</ThemedText>)
+    .toJSON();
+
+  expect(tree).toMatchSnapshot();
+});

components/__tests__/__snapshots__/ThemedText-test.tsx.snap

@@ -0,0 +1,24 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`renders correctly 1`] = `
+<Text
+  style={
+    [
+      {
+        "color": "#11181C",
+      },
+      {
+        "fontSize": 16,
+        "lineHeight": 24,
+      },
+      undefined,
+      undefined,
+      undefined,
+      undefined,
+      undefined,
+    ]
+  }
+>
+  Snapshot test!
+</Text>
+`;