feat: add testing guide

docs/testing.md

@@ -0,0 +1,25 @@
+---
+id: testing
+title: Testing
+---
+
+NativeBase works with react-native's jest preset or expo's jest-expo preset. However, there's one thing you'll need to do for it to work as expected.
+
+### Adding initialWindowMetrics in NativeBaseProvider.
+
+- NativeBaseProvider uses [SafeAreaContext](https://github.com/th3rdwave/react-native-safe-area-context#testing) which needs initialWindowMetrics to be passed to the Provider while testing.
+
+Not following the above may lead to an error related to SafeAreaProvider while running `yarn test`.
+
+To fix the above issue, you can simply pass initialWindowMetrics to NativeBaseProvider in your tests.
+
+```jsx
+const inset = {
+  frame: { x: 0, y: 0, width: 0, height: 0 },
+  insets: { top: 0, left: 0, right: 0, bottom: 0 },
+};
+
+<NativeBaseProvider initialWindowMetrics={inset}>
+  {children}
+</NativeBaseProvider>;
+```

sidebars.js

@@ -207,6 +207,10 @@ module.exports = {
         'use-accessible-colors',
       ],
     },
+    {
+      type: 'doc',
+      id: 'testing',
+    },
     {
       type: 'category',
       label: 'Examples',