Break up ReactDOMServerIntegrationForm-test (facebook#13600)

In facebook#13394, I encountered an
issue where the ReactDOMServerIntegrationForm test suite consumed
sufficient memory to crash CircleCI. Breaking up this test suite by
form element type resolved the issue.

This commit performs that change separate from the Symbol/Function
stringification changes in facebook#13394.

packages/react-dom/src/__tests__/ReactDOMServerIntegrationCheckbox-test.js

@@ -0,0 +1,99 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+const ReactDOMServerIntegrationUtils = require('./utils/ReactDOMServerIntegrationTestUtils');
+
+let React;
+let ReactDOM;
+let ReactDOMServer;
+
+function initModules() {
+  // Reset warning cache.
+  jest.resetModuleRegistry();
+  React = require('react');
+  ReactDOM = require('react-dom');
+  ReactDOMServer = require('react-dom/server');
+
+  // Make them available to the helpers.
+  return {
+    ReactDOM,
+    ReactDOMServer,
+  };
+}
+
+const {resetModules, itRenders} = ReactDOMServerIntegrationUtils(initModules);
+
+describe('ReactDOMServerIntegrationCheckbox', () => {
+  beforeEach(() => {
+    resetModules();
+  });
+
+  itRenders('a checkbox that is checked with an onChange', async render => {
+    const e = await render(
+      <input type="checkbox" checked={true} onChange={() => {}} />,
+    );
+    expect(e.checked).toBe(true);
+  });
+
+  itRenders('a checkbox that is checked with readOnly', async render => {
+    const e = await render(
+      <input type="checkbox" checked={true} readOnly={true} />,
+    );
+    expect(e.checked).toBe(true);
+  });
+
+  itRenders(
+    'a checkbox that is checked and no onChange/readOnly',
+    async render => {
+      // this configuration should raise a dev warning that checked without
+      // onChange or readOnly is a mistake.
+      const e = await render(<input type="checkbox" checked={true} />, 1);
+      expect(e.checked).toBe(true);
+    },
+  );
+
+  itRenders('a checkbox with defaultChecked', async render => {
+    const e = await render(<input type="checkbox" defaultChecked={true} />);
+    expect(e.checked).toBe(true);
+    expect(e.getAttribute('defaultChecked')).toBe(null);
+  });
+
+  itRenders('a checkbox checked overriding defaultChecked', async render => {
+    const e = await render(
+      <input
+        type="checkbox"
+        checked={true}
+        defaultChecked={false}
+        readOnly={true}
+      />,
+      1,
+    );
+    expect(e.checked).toBe(true);
+    expect(e.getAttribute('defaultChecked')).toBe(null);
+  });
+
+  itRenders(
+    'a checkbox checked overriding defaultChecked no matter the prop order',
+    async render => {
+      const e = await render(
+        <input
+          type="checkbox"
+          defaultChecked={false}
+          checked={true}
+          readOnly={true}
+        />,
+        1,
+      );
+      expect(e.checked).toBe(true);
+      expect(e.getAttribute('defaultChecked')).toBe(null);
+    },
+  );
+});