Make storePart argument optional in overloads

Author: luisherranz

packages/interactivity/src/store.ts

@@ -179,14 +179,14 @@ export function store< T extends object >(
 // Overload for when types are passed via generics and they contain state.
 export function store< T extends { state: object } >(
 	namespace: string,
-	storePart: ConvertPromisesToGenerators< DeepPartialState< T > >,
+	storePart?: ConvertPromisesToGenerators< DeepPartialState< T > >,
 	options?: StoreOptions
 ): Prettify< ConvertGeneratorsToPromises< T > >;
 
 // Overload for when types are passed via generics and they don't contain state.
 export function store< T extends object >(
 	namespace: string,
-	storePart: ConvertPromisesToGenerators< T >,
+	storePart?: ConvertPromisesToGenerators< T >,
 	options?: StoreOptions
 ): Prettify< ConvertGeneratorsToPromises< T > >;
 

packages/interactivity/src/test/store.ts

@@ -281,6 +281,29 @@ describe( 'Interactivity API', () => {
 					myStore.state.nonExistent satisfies {};
 				};
 			} );
+
+			describe( 'a typed store can be returned without adding a new store part', () => {
+				type State = {
+					someValue: number;
+				};
+				type Actions = {
+					incrementValue: ( n: number ) => void;
+				};
+
+				const { state, actions } = store< {
+					state: State;
+					actions: Actions;
+				} >( 'storeWithState' );
+
+				state.someValue satisfies number;
+				actions.incrementValue( 1 ) satisfies void;
+
+				const { actions: actions2 } = store< { actions: Actions } >(
+					'storeWithoutState'
+				);
+
+				actions2.incrementValue( 1 ) satisfies void;
+			} );
 		} );
 	} );
 } );