add failing test

packages/context-state2/src/combineStates.test.ts

@@ -86,6 +86,28 @@ describe("combineStates", () => {
     })
   })
 
+  it("updates when one of the sources updates", () => {
+    const root = createRoot()
+    const source$ = new Subject<string>()
+    const nodeA = substate(root, () => source$)
+    const nodeB = substate(root, () => of("b"))
+
+    const combined = combineStates({ nodeA, nodeB })
+    root.run()
+
+    source$.next("a")
+    expect(combined.getValue({ root: "" })).toEqual({
+      nodeA: "a",
+      nodeB: "b",
+    })
+
+    source$.next("2")
+    expect(combined.getValue({ root: "" })).toEqual({
+      nodeA: "2",
+      nodeB: "b",
+    })
+  })
+
   it("doesn't emit a value until all branches have one", async () => {
     function createSettableNode<K extends Record<string, any>>(
       root: StateNode<never, K>,

packages/context-state2/src/substate.test.ts

@@ -300,6 +300,29 @@ describe("subState", () => {
       expect(nodeB.getValue()).toBe("b")
       expect(nodeA.getValue()).toBe("b-a")
     })
+
+    it.only("can reference its siblings after a change", () => {
+      const root = createRoot()
+      const source$ = new Subject<string>()
+      const subNode = substate(root, () => source$)
+      const nodeA = substate(subNode, (ctx, getState$) =>
+        getState$(nodeB, {}).pipe(map((v) => ctx(subNode) + "-" + v + "-a")),
+      )
+      const nodeB = substate(subNode, (ctx) => of("b" + ctx(subNode)))
+
+      root.run()
+
+      expect(nodeA.getValue()).toBeInstanceOf(Promise)
+      source$.next("1")
+
+      expect(nodeB.getValue()).toBe("b1")
+      expect(nodeA.getValue()).toBe("1-b1-a")
+
+      source$.next("2")
+
+      expect(nodeB.getValue()).toBe("b2")
+      expect(nodeA.getValue()).toBe("2-b2-a")
+    })
   })
 
   describe("state$", () => {

packages/context-state2/src/substate.ts

@@ -41,6 +41,8 @@ export const substate = <T, K extends KeysBaseType>(
         next: () => {
           stateNode.resetInstance(instanceKey)
           // TODO shouldn't re-activation of instances happen after all subscribers have restarted? how to do it?
+          // Yes. I would need a special kind of observable so that I can first reset the instances without activating them
+          // and then synchronously activate them
         },
         error: () => {
           // TODO