fix: Correctly read descriptions of local spread objects (#282)

Author: danez

src/__tests__/__snapshots__/main-test.js.snap

@@ -865,3 +865,25 @@ Object {
   },
 }
 `;
+
+exports[`main fixtures processes component "component_16.js" without errors 1`] = `
+Object {
+  "description": "",
+  "displayName": "Foo",
+  "methods": Array [],
+  "props": Object {
+    "bar": Object {
+      "defaultValue": Object {
+        "computed": false,
+        "value": "null",
+      },
+      "description": "This does something.",
+      "required": false,
+      "type": Object {
+        "name": "custom",
+        "raw": "PropTypes.node",
+      },
+    },
+  },
+}
+`;

src/__tests__/fixtures/component_16.js

@@ -0,0 +1,16 @@
+const propTypes = {
+  /** This does something. */
+  bar: PropTypes.node,
+};
+
+export default function Foo(props) {
+  return <div />;
+}
+
+Foo.propTypes = {
+  ...propTypes
+};
+
+Foo.defaultProps = {
+  bar: null,
+};

src/handlers/propDocBlockHandler.js

@@ -21,6 +21,24 @@ const {
   types: { namedTypes: types },
 } = recast;
 
+function resolveDocumentation(
+  documentation: Documentation,
+  path: NodePath,
+): void {
+  if (!types.ObjectExpression.check(path.node)) {
+    return;
+  }
+
+  path.get('properties').each(propertyPath => {
+    if (types.Property.check(propertyPath.node)) {
+      setPropDescription(documentation, propertyPath);
+    } else if (types.SpreadElement.check(propertyPath.node)) {
+      const resolvedValuePath = resolveToValue(propertyPath.get('argument'));
+      resolveDocumentation(documentation, resolvedValuePath);
+    }
+  });
+}
+
 export default function propDocBlockHandler(
   documentation: Documentation,
   path: NodePath,
@@ -30,14 +48,9 @@ export default function propDocBlockHandler(
     return;
   }
   propTypesPath = resolveToValue(propTypesPath);
-  if (!propTypesPath || !types.ObjectExpression.check(propTypesPath.node)) {
+  if (!propTypesPath) {
     return;
   }
 
-  propTypesPath.get('properties').each(propertyPath => {
-    // we only support documentation of actual properties, not spread
-    if (types.Property.check(propertyPath.node)) {
-      setPropDescription(documentation, propertyPath);
-    }
-  });
+  resolveDocumentation(documentation, propTypesPath);
 }