context-state: fix route-state broken tests

packages/context-state/src/internal/detached-node.ts

@@ -106,7 +106,9 @@ export const detachedNode = <T>(
 
     if (isParentLoaded) {
       // an actual change of context
-      const hasPreviousValue = instance && instance.currentValue !== EMPTY_VALUE
+      let previousValue = instance ? instance.currentValue : EMPTY_VALUE
+      const hasPreviousValue = previousValue !== EMPTY_VALUE
+
       if (!instance) {
         instance = {
           subject: new ReplaySubject<T>(1),
@@ -154,7 +156,10 @@ export const detachedNode = <T>(
       actualInstance.subscription =
         observable?.subscribe({
           next(value) {
-            let prevValue = actualInstance.currentValue
+            let prevValue =
+              previousValue !== EMPTY_VALUE
+                ? previousValue
+                : actualInstance.currentValue
             actualInstance.currentValue = value
             const prevPromise = actualInstance.promise
             actualInstance.promise = null
@@ -186,6 +191,8 @@ export const detachedNode = <T>(
         runChildren(key, true, false)
         prevSubect?.complete()
       }
+
+      previousValue = EMPTY_VALUE
       return
     }
 

packages/context-state/src/route-state.test.ts

@@ -40,7 +40,9 @@ describe("routeState", () => {
       )
       root.run()
 
-      expect(() => key.getValue()).toThrow() // TODO which error?
+      expect(() => key.getValue()).toThrow(
+        'Invalid Route. Received "c" while valid keys are: "a, b"',
+      )
     })
 
     it("errors if the selector throws an error", () => {

packages/context-state/src/route-state.ts

@@ -10,6 +10,17 @@ import { of } from "rxjs"
 import { substate } from "./substate"
 import { StateNode, Ctx } from "./types"
 
+export class InvalidRouteError extends Error {
+  constructor(key: string, keys: string[]) {
+    super(
+      `Invalid Route. Received "${key}" while valid keys are: "${keys.join(
+        ", ",
+      )}"`,
+    )
+    this.name = "InvalidRouteError"
+  }
+}
+
 export const routeState = <
   T,
   O extends { [P in keyof any]: ((value: T) => any) | null },
@@ -25,7 +36,12 @@ export const routeState = <
   routes: O,
   selector: (value: T, ctx: Ctx) => keyof O,
 ): [StateNode<keyof O>, OT] => {
-  const keyState = substate(parent, (ctx) => of(selector(ctx(parent), ctx)))
+  const keys = new Set(Object.keys(routes))
+  const keyState = substate(parent, (ctx) => {
+    const key = selector(ctx(parent), ctx) as string
+    if (!keys.has(key)) throw new InvalidRouteError(key, [...keys])
+    return of(key)
+  })
 
   const routedState = mapRecord(routes, (mapper) => {
     const result = detachedNode<any>((ctx) => {