Fix recursion in sync routine. (#13818)

packages/redux-routine/CHANGELOG.md

@@ -4,7 +4,8 @@
 
 - Fix unhandled promise rejection error caused by returning null from registered generator ([#13314](https://github.com/WordPress/gutenberg/pull/13314))
 - The middleware will no longer attempt to coerce an error to an instance of `Error`, and instead passes through the thrown value directly. This resolves issues where an `Error` would be thrown when the underlying values were not of type `Error` or `string` (e.g. a thrown object) and the message would end up not being useful (e.g. `[Object object]`).
-([#13315](https://github.com/WordPress/gutenberg/pull/13315)) 
+([#13315](https://github.com/WordPress/gutenberg/pull/13315))
+- Fix unintended recursion when invoking sync routine ([#13818](https://github.com/WordPress/gutenberg/pull/13818))
 
 ## 3.0.3 (2018-10-19)
 

packages/redux-routine/src/runtime.js

@@ -28,7 +28,7 @@ export default function createRuntime( controls = {}, dispatch ) {
 			// Async control routine awaits resolution.
 			routine.then( yieldNext, yieldError );
 		} else {
-			next( routine );
+			yieldNext( routine );
 		}
 		return true;
 	} );

packages/redux-routine/src/test/index.js

@@ -143,4 +143,21 @@ describe( 'createMiddleware', () => {
 
 		expect( store.getState() ).toBe( 2 );
 	} );
+
+	it( 'does not recurse when action like object returns from a sync ' +
+		'control', () => {
+		const post = { type: 'post' };
+		const middleware = createMiddleware( {
+			UPDATE: () => post,
+		} );
+		const store = createStoreWithMiddleware( middleware );
+		function* getPostAction() {
+			const nextState = yield { type: 'UPDATE' };
+			return { type: 'CHANGE', nextState };
+		}
+
+		store.dispatch( getPostAction() );
+
+		expect( store.getState() ).toEqual( post );
+	} );
 } );