feat(events): check returned event flags in DEBUG mode

localvoid · May 23, 2018 · 2fc17db · 2fc17db
1 parent f83f779
commit 2fc17db
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diff --git a/packages/ivi-events/src/__tests__/dispatch.spec.ts b/packages/ivi-events/src/__tests__/dispatch.spec.ts
@@ -186,3 +186,16 @@ describe("event flow", () => {
     expect(order).toEqual([2]);
   });
 });
+
+test(`returning invalid EventFlags should raise an exception`, () => {
+  const t1 = document.createElement("div");
+  const h1 = onClick(() => (10));
+
+  expect(() => {
+    dispatchEvent(
+      [{ target: t1, handlers: h1 }],
+      new SyntheticNativeEvent<MouseEvent>(0, t1, 0, new MouseEvent("click")),
+      true,
+    );
+  }).toThrowError(`Invalid`);
+});
diff --git a/packages/ivi-events/src/dispatch.ts b/packages/ivi-events/src/dispatch.ts
@@ -22,6 +22,13 @@ function _dispatch(
   event: SyntheticEvent,
 ): EventFlags {
   const flags = (dispatch === void 0) ? handler.handler(event) : dispatch(handler, event);
+  if (DEBUG) {
+    if (flags !== void 0) {
+      if (flags & ~(EventFlags.PreventDefault | EventFlags.StopPropagation)) {
+        throw new Error(`Invalid event flags: ${flags}`);
+      }
+    }
+  }
   return (flags === void 0) ? 0 : flags;
 }