feat: add toJSON to render; cleanup shallow

package.json

@@ -30,9 +30,6 @@
     "react": ">=16.0.0",
     "react-test-renderer": ">= 16.0.0"
   },
-  "dependencies": {
-    "react-is": "^16.5.2"
-  },
   "scripts": {
     "test": "jest",
     "flow-check": "flow check",

src/__tests__/__snapshots__/render.test.js.snap

@@ -0,0 +1,3 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`toJSON 1`] = `"press me"`;

src/__tests__/render.test.js

@@ -161,3 +161,9 @@ test('unmount', () => {
   unmount();
   expect(fn).toHaveBeenCalled();
 });
+
+test('toJSON', () => {
+  const { toJSON } = render(<Button>press me</Button>);
+
+  expect(toJSON()).toMatchSnapshot();
+});

src/debug.js

@@ -1,7 +1,7 @@
 // @flow
 import * as React from 'react';
 import prettyFormat, { plugins } from 'pretty-format'; // eslint-disable-line import/no-extraneous-dependencies
-import shallow from './shallow';
+import { shallow } from '.';
 
 /**
  * Log pretty-printed shallow test component instance

src/render.js

@@ -20,5 +20,6 @@ export default function render(
     ...queryByAPI(instance),
     update: renderer.update,
     unmount: renderer.unmount,
+    toJSON: renderer.toJSON,
   };
 }

src/shallow.js

@@ -1,6 +1,5 @@
 // @flow
 import * as React from 'react';
-import { isValidElementType } from 'react-is';
 import ShallowRenderer from 'react-test-renderer/shallow'; // eslint-disable-line import/no-extraneous-dependencies
 
 /**
@@ -10,15 +9,10 @@ export default function shallow(
   instance: ReactTestInstance | React.Element<*>
 ) {
   const renderer = new ShallowRenderer();
-  if (isValidElementType(instance)) {
-    // $FlowFixMe - instance is React.Element<*> in this branch
-    renderer.render(instance);
-  } else {
-    renderer.render(React.createElement(instance.type, instance.props));
-  }
-  const output = renderer.getRenderOutput();
+
+  renderer.render(React.createElement(instance.type, instance.props));
 
   return {
-    output,
+    output: renderer.getRenderOutput(),
   };
 }