1 files changed, 12 insertions, 8 deletions
diff --git a/pbt/ts/src/property.ts b/pbt/ts/src/property.ts
index 56683c1..635e731 100644
--- a/pbt/ts/src/property.ts
+++ b/pbt/ts/src/property.ts
@@ -53,11 +53,11 @@ export function generate<A>(gen: Gen<A>): A {
   return gen(rng)(100);
 }
 
-export function property<A>(
+export async function property<A>(
   generator: Gen<A>,
   predicate: Predicate<A>,
   shrinker?: Shrinker<A>,
-): Property<A> {
+): Promise<Property<A>> {
   return async (seed: number, size: number) => {
     const rng = new Prando(seed);
     const gen = generator(rng);
@@ -243,9 +243,10 @@ export function shrinkPair<A, B>(
 }
 
 export const Property = {
-  run<A>(prop: Property<A>): Promise<TestResult<A>> {
+  async run<A>(prop: Promise<Property<A>>): Promise<TestResult<A>> {
     const seed = Math.floor(Math.random() * 1000000);
-    return prop(seed, 0);
+    const p = await prop;
+    return await p(seed, 0);
   },
 };
 
@@ -253,11 +254,14 @@ export const Property = {
 
 export function forall<A, B>(
   gen: Gen<A>,
-  k: (a: A) => Property<B>,
-): Property<B> {
-  return (seed: number, size: number) => {
+  k: (a: A) => Promise<Property<B>>,
+): Promise<Property<B>> {
+  const p = async (seed: number, size: number) => {
     const rng = new Prando(seed);
     const a = gen(rng)(size);
-    return k(a)(seed, size);
+    const p = await k(a);
+    return await p(seed, size);
   };
+
+  return Promise.resolve(p);
 }