RN: Create `NativeComponentRegistry`

Summary:
Creates `NativeComponentRegistry` which makes native component initialization more declarative and configurable through an optionally configurable provider.

The next diff converts `ScrollView` to use this new abstraction as a demonstration. The plan would be to use this to replace all current manual call sites of `registerGeneratedViewConfig`, and then the ones generated via the Babel plugin.

Migrating to this will not change any production behavior, but it will enable verification of `ViewConfig` in development.

Changelog:
[Internal]

Reviewed By: JoshuaGross

Differential Revision: D25084468

fbshipit-source-id: 9c758ddc279bf937a401a868a066907a94098f37

Libraries/NativeComponent/NativeComponentRegistry.js

@@ -0,0 +1,78 @@
+/**
+ * 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.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+'use strict';
+
+import {createViewConfig} from './ViewConfig';
+import type {
+  HostComponent,
+  PartialViewConfig,
+} from '../Renderer/shims/ReactNativeTypes';
+import ReactNativeViewConfigRegistry from '../Renderer/shims/ReactNativeViewConfigRegistry';
+import getNativeComponentAttributes from '../ReactNative/getNativeComponentAttributes';
+import verifyComponentAttributeEquivalence from '../Utilities/verifyComponentAttributeEquivalence';
+import invariant from 'invariant';
+
+let getRuntimeConfig;
+
+/**
+ * Configures a function that is called to determine whether a given component
+ * should be registered using reflection of the native component at runtime.
+ */
+export function setRuntimeConfigProvider(
+  runtimeConfigProvider: (name: string) => {native: boolean, verify: boolean},
+): void {
+  invariant(
+    getRuntimeConfig == null,
+    'NativeComponentRegistry.setRuntimeConfigProvider() called more than once.',
+  );
+  getRuntimeConfig = runtimeConfigProvider;
+}
+
+/**
+ * Gets a `NativeComponent` that can be rendered by React Native.
+ *
+ * The supplied `viewConfigProvider` may or may not be invoked and utilized,
+ * depending on how `setRuntimeConfigProvider` is configured.
+ */
+export function get<Config>(
+  name: string,
+  viewConfigProvider: () => PartialViewConfig,
+): HostComponent<Config> {
+  ReactNativeViewConfigRegistry.register(name, () => {
+    const {native, verify} = getRuntimeConfig?.(name) ?? {
+      native: true,
+      verify: false,
+    };
+
+    const viewConfig = native
+      ? getNativeComponentAttributes(name)
+      : createViewConfig(viewConfigProvider());
+
+    if (verify) {
+      if (native) {
+        verifyComponentAttributeEquivalence(
+          viewConfig,
+          createViewConfig(viewConfigProvider()),
+        );
+      } else {
+        verifyComponentAttributeEquivalence(
+          getNativeComponentAttributes(name),
+          viewConfig,
+        );
+      }
+    }
+
+    return viewConfig;
+  });
+
+  // $FlowFixMe[incompatible-return] `NativeComponent` is actually string!
+  return name;
+}

jest/mockNativeComponent.js

@@ -0,0 +1,36 @@
+/**
+ * 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.
+ *
+ * @format
+ */
+
+'use strict';
+
+const React = require('react');
+
+module.exports = viewName => {
+  const Component = class extends React.Component {
+    render() {
+      return React.createElement(viewName, this.props, this.props.children);
+    }
+
+    // The methods that exist on host components
+    blur = jest.fn();
+    focus = jest.fn();
+    measure = jest.fn();
+    measureInWindow = jest.fn();
+    measureLayout = jest.fn();
+    setNativeProps = jest.fn();
+  };
+
+  if (viewName === 'RCTView') {
+    Component.displayName = 'View';
+  } else {
+    Component.displayName = viewName;
+  }
+
+  return Component;
+};

jest/setup.js

@@ -325,33 +325,17 @@ jest
       }),
     },
   }))
-  .mock('../Libraries/ReactNative/requireNativeComponent', () => {
-    const React = require('react');
-
-    return viewName => {
-      const Component = class extends React.Component {
-        render() {
-          return React.createElement(viewName, this.props, this.props.children);
-        }
-
-        // The methods that exist on host components
-        blur = jest.fn();
-        focus = jest.fn();
-        measure = jest.fn();
-        measureInWindow = jest.fn();
-        measureLayout = jest.fn();
-        setNativeProps = jest.fn();
-      };
-
-      if (viewName === 'RCTView') {
-        Component.displayName = 'View';
-      } else {
-        Component.displayName = viewName;
-      }
-
-      return Component;
+  .mock('../Libraries/NativeComponent/NativeComponentRegistry', () => {
+    return {
+      get: jest.fn((name, viewConfigProvider) => {
+        return jest.requireActual('./mockNativeComponent')(name);
+      }),
+      setRuntimeConfigProvider: jest.fn(),
     };
   })
+  .mock('../Libraries/ReactNative/requireNativeComponent', () => {
+    return jest.requireActual('./mockNativeComponent');
+  })
   .mock(
     '../Libraries/Utilities/verifyComponentAttributeEquivalence',
     () => function() {},