improve unit tests

Author: birkskyum

packages/router-core/src/router.ts

@@ -710,7 +710,7 @@ export type CommitLocationFn = ({
   ...next
 }: ParsedLocation & CommitLocationOptions) => Promise<void>
 
-export type StartTransitionFn = (fn: () => void) => void
+export type StartTransitionFn = (fn: () => void | Promise<void>) => void
 
 export interface MatchRoutesFn {
   (

packages/solid-router/src/Transitioner.tsx

@@ -37,13 +37,14 @@ export function Transitioner() {
 
   router.startTransition = (fn: () => void | Promise<void>) => {
     setIsTransitioning(true)
-    Solid.startTransition(async () => {
-      try {
-        await fn()
-      } finally {
+    const result = fn()
+    if (result instanceof Promise) {
+      result.finally(() => {
         setIsTransitioning(false)
-      }
-    })
+      })
+    } else {
+      setIsTransitioning(false)
+    }
   }
 
   // Subscribe to location changes