feat(defaultPropsHandler): Fully support forwardRef (#350)

* test(failing): defaultPropsHandler and forwardRef

* feat(defaultPropsHandler): support forwardRef

Author: eps1lon

src/handlers/__tests__/__snapshots__/defaultPropsHandler-test.js.snap

@@ -226,6 +226,28 @@ Object {
 }
 `;
 
+exports[`defaultPropsHandler forwardRef resolves default props in the parameters 1`] = `
+Object {
+  "foo": Object {
+    "defaultValue": Object {
+      "computed": false,
+      "value": "'bar'",
+    },
+  },
+}
+`;
+
+exports[`defaultPropsHandler forwardRef resolves defaultProps 1`] = `
+Object {
+  "foo": Object {
+    "defaultValue": Object {
+      "computed": false,
+      "value": "'baz'",
+    },
+  },
+}
+`;
+
 exports[`defaultPropsHandler should only consider Property nodes, not e.g. spread properties 1`] = `
 Object {
   "bar": Object {

src/handlers/__tests__/defaultPropsHandler-test.js

@@ -219,4 +219,28 @@ describe('defaultPropsHandler', () => {
       expect(documentation.descriptors).toMatchSnapshot();
     });
   });
+
+  describe('forwardRef', () => {
+    it('resolves default props in the parameters', () => {
+      const src = `
+        import React from 'react';
+        React.forwardRef(({ foo = 'bar' }, ref) => <div ref={ref}>{foo}</div>);
+      `;
+      defaultPropsHandler(
+        documentation,
+        parse(src).get('body', 1, 'expression'),
+      );
+      expect(documentation.descriptors).toMatchSnapshot();
+    });
+
+    it('resolves defaultProps', () => {
+      const src = `
+        import React from 'react';
+        const Component = React.forwardRef(({ foo }, ref) => <div ref={ref}>{foo}</div>);
+        Component.defaultProps = { foo: 'baz' };
+      `;
+      defaultPropsHandler(documentation, parse(src).get('body', 1));
+      expect(documentation.descriptors).toMatchSnapshot();
+    });
+  });
 });

src/handlers/defaultPropsHandler.js

@@ -15,7 +15,8 @@ import printValue from '../utils/printValue';
 import recast from 'recast';
 import resolveToValue from '../utils/resolveToValue';
 import resolveFunctionDefinitionToReturnValue from '../utils/resolveFunctionDefinitionToReturnValue';
-import isStatelessComponent from '../utils/isStatelessComponent';
+import isReactComponentClass from '../utils/isReactComponentClass';
+import isReactForwardRefCall from '../utils/isReactForwardRefCall';
 
 const {
   types: { namedTypes: types },
@@ -53,7 +54,12 @@ function getDefaultValue(path: NodePath) {
 }
 
 function getStatelessPropsPath(componentDefinition): NodePath {
-  return resolveToValue(componentDefinition).get('params', 0);
+  const value = resolveToValue(componentDefinition);
+  if (isReactForwardRefCall(value)) {
+    const inner = value.get('arguments', 0);
+    return inner.get('params', 0);
+  }
+  return value.get('params', 0);
 }
 
 function getDefaultPropsPath(componentDefinition: NodePath): ?NodePath {
@@ -118,7 +124,10 @@ export default function defaultPropsHandler(
 ) {
   let statelessProps = null;
   const defaultPropsPath = getDefaultPropsPath(componentDefinition);
-  if (isStatelessComponent(componentDefinition)) {
+  /**
+   * function, lazy, memo, forwardRef etc components can resolve default props as well
+   */
+  if (!isReactComponentClass(componentDefinition)) {
     statelessProps = getStatelessPropsPath(componentDefinition);
   }