From bfc9b8bcd4d2ce4de113e5eba812d8be980864df Mon Sep 17 00:00:00 2001
From: Josep M Sobrepere <josepot@gmail.com>
Date: Wed, 13 Jan 2021 14:56:06 +0100
Subject: [PATCH] fix(bind): the default value can be undefined

---
 .../src/bind/connectFactoryObservable.test.tsx  | 17 +++++++++++++++++
 .../core/src/bind/connectFactoryObservable.ts   |  2 +-
 .../core/src/bind/connectObservable.test.tsx    | 17 +++++++++++++++++
 packages/core/src/bind/connectObservable.ts     |  2 +-
 packages/core/src/bind/index.ts                 |  7 +++++--
 packages/core/src/internal/share-latest.ts      |  2 +-
 packages/core/src/shareLatest.ts                |  3 ++-
 7 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/packages/core/src/bind/connectFactoryObservable.test.tsx b/packages/core/src/bind/connectFactoryObservable.test.tsx
index 8b2ab22..9f2e195 100644
--- a/packages/core/src/bind/connectFactoryObservable.test.tsx
+++ b/packages/core/src/bind/connectFactoryObservable.test.tsx
@@ -522,6 +522,23 @@ describe("connectFactoryObservable", () => {
       subscription.unsubscribe()
     })
 
+    it("the defaultValue can be undefined", () => {
+      const number$ = new Subject<number>()
+      const [useNumber] = bind(() => number$, undefined)
+
+      const { result, unmount } = renderHook(() => useNumber())
+
+      expect(result.current).toBe(undefined)
+
+      actHook(() => {
+        number$.next(5)
+      })
+
+      expect(result.current).toBe(5)
+
+      unmount()
+    })
+
     it("if the observable hasn't emitted and a defaultValue is provided, it does not start suspense", () => {
       const number$ = new Subject<number>()
       const [useNumber] = bind(
diff --git a/packages/core/src/bind/connectFactoryObservable.ts b/packages/core/src/bind/connectFactoryObservable.ts
index 670b195..1e6154f 100644
--- a/packages/core/src/bind/connectFactoryObservable.ts
+++ b/packages/core/src/bind/connectFactoryObservable.ts
@@ -45,8 +45,8 @@ export default function connectFactoryObservable<A extends [], O>(
 
     const sharedObservable$ = shareLatest(
       getObservable(...input),
-      false,
       defaultValue,
+      false,
       () => {
         cache.delete(keys)
       },
diff --git a/packages/core/src/bind/connectObservable.test.tsx b/packages/core/src/bind/connectObservable.test.tsx
index c495a7e..4c17fbb 100644
--- a/packages/core/src/bind/connectObservable.test.tsx
+++ b/packages/core/src/bind/connectObservable.test.tsx
@@ -650,6 +650,23 @@ describe("connectObservable", () => {
     expect(errorCallback).toHaveBeenCalled()
   })
 
+  it("the defaultValue can be undefined", () => {
+    const number$ = new Subject<number>()
+    const [useNumber] = bind(number$, undefined)
+
+    const { result, unmount } = renderHook(() => useNumber())
+
+    expect(result.current).toBe(undefined)
+
+    act(() => {
+      number$.next(5)
+    })
+
+    expect(result.current).toBe(5)
+
+    unmount()
+  })
+
   it("if the observable hasn't emitted and a defaultValue is provided, it does not start suspense", () => {
     const number$ = new Subject<number>()
     const [useNumber] = bind(number$, 0)
diff --git a/packages/core/src/bind/connectObservable.ts b/packages/core/src/bind/connectObservable.ts
index d942e7e..b4cca34 100644
--- a/packages/core/src/bind/connectObservable.ts
+++ b/packages/core/src/bind/connectObservable.ts
@@ -21,7 +21,7 @@ export default function connectObservable<T>(
   observable: Observable<T>,
   defaultValue: T,
 ) {
-  const sharedObservable$ = shareLatest<T>(observable, false, defaultValue)
+  const sharedObservable$ = shareLatest<T>(observable, defaultValue, false)
   const useStaticObservable = () => useObservable(sharedObservable$)
   return [useStaticObservable, sharedObservable$] as const
 }
diff --git a/packages/core/src/bind/index.ts b/packages/core/src/bind/index.ts
index c7635bd..1fe8398 100644
--- a/packages/core/src/bind/index.ts
+++ b/packages/core/src/bind/index.ts
@@ -46,8 +46,11 @@ export function bind<A extends unknown[], O>(
   defaultValue?: O,
 ): [(...args: A) => Exclude<O, typeof SUSPENSE>, (...args: A) => Observable<O>]
 
-export function bind(observable: any, defaultValue: any = EMPTY_VALUE) {
+export function bind(observable: any, defaultValue: any) {
   return (typeof observable === "function"
     ? (connectFactoryObservable as any)
-    : connectObservable)(observable, defaultValue)
+    : connectObservable)(
+    observable,
+    arguments.length > 1 ? defaultValue : EMPTY_VALUE,
+  )
 }
diff --git a/packages/core/src/internal/share-latest.ts b/packages/core/src/internal/share-latest.ts
index e2efcba..7acd943 100644
--- a/packages/core/src/internal/share-latest.ts
+++ b/packages/core/src/internal/share-latest.ts
@@ -5,8 +5,8 @@ import { SUSPENSE } from "../SUSPENSE"
 
 const shareLatest = <T>(
   source$: Observable<T>,
+  defaultValue: T,
   shouldComplete = true,
-  defaultValue: T = EMPTY_VALUE,
   teardown = noop,
 ): BehaviorObservable<T> => {
   let subject: Subject<T> | null
diff --git a/packages/core/src/shareLatest.ts b/packages/core/src/shareLatest.ts
index 1d45f1e..e264ec8 100644
--- a/packages/core/src/shareLatest.ts
+++ b/packages/core/src/shareLatest.ts
@@ -1,5 +1,6 @@
 import { Observable, MonoTypeOperatorFunction } from "rxjs"
 import internalShareLatest from "./internal/share-latest"
+import { EMPTY_VALUE } from "./internal/empty-value"
 
 /**
  * A RxJS pipeable operator which shares and replays the latest emitted value.
@@ -17,4 +18,4 @@ import internalShareLatest from "./internal/share-latest"
  */
 export const shareLatest = <T>(): MonoTypeOperatorFunction<T> => (
   source$: Observable<T>,
-) => internalShareLatest(source$)
+) => internalShareLatest(source$, EMPTY_VALUE)