Add early invariants for bad method results

react-dnd · May 1, 2015 · 18a2cad · 18a2cad
1 parent fdad029
commit 18a2cad
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Showing 2 changed files with 21 additions and 2 deletions.
diff --git a/src/ComponentDragSource.js b/src/ComponentDragSource.js
@@ -93,7 +93,16 @@ export default class ComponentDragSource extends DragSource {
 
   beginDrag(monitor, id) {
     const component = this.getComponentRef();
-    return this.spec.beginDrag.call(null, this.props, monitor, component, id);
+    const item = this.spec.beginDrag.call(null, this.props, monitor, component, id);
+    if (process.env.NODE_ENV !== 'production') {
+      invariant(
+        isObject(item) && typeof item !== 'function',
+        'beginDrag() must return an object that represents the dragged item. ' +
+        'Instead received %s.',
+        item
+      );
+    }
+    return item;
   }
 
   endDrag(monitor, id) {

diff --git a/src/ComponentDropTarget.js b/src/ComponentDropTarget.js
@@ -83,7 +83,17 @@ export default class ComponentDropTarget extends DropTarget {
   drop(monitor, id) {
     if (this.spec.drop) {
       const component = this.getComponentRef();
-      return this.spec.drop.call(null, this.props, monitor, component, id);
+      const dropResult = this.spec.drop.call(null, this.props, monitor, component, id);
+      if (process.env.NODE_ENV !== 'production') {
+        invariant(
+          typeof dropResult === 'undefined' ||
+          isObject(dropResult) && typeof dropResult !== 'function',
+          'drop() must either return undefined, or an object that represents the drop result. ' +
+          'Instead received %s.',
+          dropResult
+        );
+      }
+      return dropResult;
     } else {
       return super.drop(monitor, id);
     }