From 49235fe80728a3803a16251d4c163f002b4bb29f Mon Sep 17 00:00:00 2001
From: Mikhail Nasyrov <streambot@gmail.com>
Date: Wed, 21 Jul 2021 00:00:57 +0700
Subject: [PATCH] fix: Types for actions and effects

---
 packages/rx-effects/src/action.test.ts  | 22 +++++++++++++
 packages/rx-effects/src/action.ts       | 11 +++----
 packages/rx-effects/src/effect.ts       | 44 ++++++++++++-------------
 packages/rx-effects/src/effectScope.ts  | 10 +++---
 packages/rx-effects/src/example.test.ts | 25 +++++++-------
 packages/rx-effects/src/stateQuery.ts   |  8 ++---
 packages/rx-effects/src/stateStore.ts   | 33 +++++++++----------
 packages/rx-effects/src/stateUtils.ts   |  2 +-
 8 files changed, 87 insertions(+), 68 deletions(-)
 create mode 100644 packages/rx-effects/src/action.test.ts

diff --git a/packages/rx-effects/src/action.test.ts b/packages/rx-effects/src/action.test.ts
new file mode 100644
index 0000000..8fe57d6
--- /dev/null
+++ b/packages/rx-effects/src/action.test.ts
@@ -0,0 +1,22 @@
+import { firstValueFrom } from 'rxjs';
+import { createAction } from './action';
+
+describe('Action', () => {
+  it('should emit the event', async () => {
+    const action = createAction<number>();
+
+    const promise = firstValueFrom(action.event$);
+    action(1);
+
+    expect(await promise).toBe(1);
+  });
+
+  it('should use void type and undefined value if a generic type is not specified', async () => {
+    const action = createAction();
+
+    const promise = firstValueFrom(action.event$);
+    action();
+
+    expect(await promise).toBe(undefined);
+  });
+});
diff --git a/packages/rx-effects/src/action.ts b/packages/rx-effects/src/action.ts
index 953e32c..0facfed 100644
--- a/packages/rx-effects/src/action.ts
+++ b/packages/rx-effects/src/action.ts
@@ -2,17 +2,16 @@ import { Observable, Subject } from 'rxjs';
 
 export type Action<Event> = {
   readonly event$: Observable<Event>;
-
-  // TODO: Check typings
-  (): void;
   (event: Event): void;
-};
+} & (Event extends undefined | void
+  ? { (event?: Event): void }
+  : { (event: Event): void });
 
-export function createAction<Event>(): Action<Event> {
+export function createAction<Event = void>(): Action<Event> {
   const source$ = new Subject<Event>();
 
   const emitter = (event: Event): void => source$.next(event);
   emitter.event$ = source$.asObservable();
 
-  return emitter as Action<Event>;
+  return emitter as unknown as Action<Event>;
 }
diff --git a/packages/rx-effects/src/effect.ts b/packages/rx-effects/src/effect.ts
index 4e803c1..7048742 100644
--- a/packages/rx-effects/src/effect.ts
+++ b/packages/rx-effects/src/effect.ts
@@ -11,24 +11,24 @@ import { Action } from './action';
 import { StateQuery } from './stateQuery';
 import { createStateStore } from './stateStore';
 
-export type Effect<Event, Result = void, ErrorType = Error> = Readonly<{
-  result$: Observable<Result>;
-  done$: Observable<{ event: Event; result: Result }>;
-  error$: Observable<{ event: Event; error: ErrorType }>;
-  final$: Observable<Event>;
-  pending: StateQuery<boolean>;
-  pendingCount: StateQuery<number>;
-
-  handle: ((event$: Observable<Event>) => Subscription) &
+export type Effect<Event, Result = void, ErrorType = Error> = {
+  readonly result$: Observable<Result>;
+  readonly done$: Observable<{ event: Event; result: Result }>;
+  readonly error$: Observable<{ event: Event; error: ErrorType }>;
+  readonly final$: Observable<Event>;
+  readonly pending: StateQuery<boolean>;
+  readonly pendingCount: StateQuery<number>;
+
+  readonly handle: ((event$: Observable<Event>) => Subscription) &
     ((action: Action<Event>) => Subscription);
-  destroy: () => void;
-}>;
+  readonly destroy: () => void;
+};
 
 export type EffectHandler<Event, Result> = (
   event: Event,
 ) => Result | Promise<Result> | Observable<Result>;
 
-export function createEffect<Event, Result = void, ErrorType = Error>(
+export function createEffect<Event = void, Result = void, ErrorType = Error>(
   handler: EffectHandler<Event, Result>,
   scopeSubscriptions?: Subscription,
 ): Effect<Event, Result, ErrorType> {
@@ -79,16 +79,14 @@ export function createEffect<Event, Result = void, ErrorType = Error>(
     try {
       const handlerResult = handler(event);
 
-      if (handlerResult) {
-        if ('then' in handlerResult) {
-          executePromise(event, handlerResult);
-          return;
-        }
+      if (handlerResult instanceof Promise) {
+        executePromise(event, handlerResult);
+        return;
+      }
 
-        if (handlerResult instanceof Observable) {
-          executeObservable(event, handlerResult);
-          return;
-        }
+      if (handlerResult instanceof Observable) {
+        executeObservable(event, handlerResult);
+        return;
       }
 
       pendingCount.update(decreaseCount);
@@ -112,7 +110,9 @@ export function createEffect<Event, Result = void, ErrorType = Error>(
   };
 
   function handle(source: Observable<Event> | Action<Event>): Subscription {
-    const observable = source instanceof Observable ? source : source.event$;
+    const observable = (
+      source instanceof Observable ? source : source.event$
+    ) as Observable<Event>;
 
     const subscription = observable.subscribe(observer);
     subscriptions.add(subscription);
diff --git a/packages/rx-effects/src/effectScope.ts b/packages/rx-effects/src/effectScope.ts
index 6ac09f0..c24ad14 100644
--- a/packages/rx-effects/src/effectScope.ts
+++ b/packages/rx-effects/src/effectScope.ts
@@ -1,14 +1,14 @@
 import { Subscription, TeardownLogic } from 'rxjs';
 import { createEffect, Effect, EffectHandler } from './effect';
 
-export type EffectScope = Readonly<{
-  add: (teardown: TeardownLogic) => void;
-  destroy: () => void;
+export type EffectScope = {
+  readonly add: (teardown: TeardownLogic) => void;
+  readonly destroy: () => void;
 
-  createEffect: <Event, Result = void, ErrorType = Error>(
+  readonly createEffect: <Event = void, Result = void, ErrorType = Error>(
     handler: EffectHandler<Event, Result>,
   ) => Effect<Event, Result, ErrorType>;
-}>;
+};
 
 export function createEffectScope(): EffectScope {
   const subscriptions = new Subscription();
diff --git a/packages/rx-effects/src/example.test.ts b/packages/rx-effects/src/example.test.ts
index 7360f64..b444ead 100644
--- a/packages/rx-effects/src/example.test.ts
+++ b/packages/rx-effects/src/example.test.ts
@@ -1,6 +1,6 @@
 import { firstValueFrom } from 'rxjs';
 import { take, toArray } from 'rxjs/operators';
-import { createAction, Action } from './action';
+import { Action, createAction } from './action';
 import { Effect } from './effect';
 import { createEffectScope, EffectScope } from './effectScope';
 import { declareState, StateDeclaration } from './stateDeclaration';
@@ -26,22 +26,23 @@ function createCalculatorEffects(
   scope: EffectScope,
   store: CalculatorStore,
 ): {
-  incrementEffect: Effect<unknown>;
+  incrementEffect: Effect<void>;
+  decrementEffect: Effect<void>;
   sumEffect: Effect<number>;
-  decrementEffect: Effect<unknown>;
-  subtractEffect: Effect<number>;
-  resetEffect: Effect<unknown>;
+  subtractEffect: Effect<number, number>;
+  resetEffect: Effect<void>;
 } {
   const incrementEffect = scope.createEffect(() => store.update(addValue(1)));
   const decrementEffect = scope.createEffect(() => store.update(addValue(-1)));
 
-  const sumEffect = scope.createEffect<number>((value) =>
+  const sumEffect = scope.createEffect((value: number) =>
     store.update(addValue(value)),
   );
 
-  const subtractEffect = scope.createEffect<number>((value) =>
-    store.update(addValue(-value)),
-  );
+  const subtractEffect = scope.createEffect((value: number) => {
+    store.update(addValue(-value));
+    return -value;
+  });
 
   const resetEffect = createResetStoreEffect(
     store,
@@ -77,11 +78,11 @@ function createCalculatorController(
 } {
   const scope = createEffectScope();
 
-  const incrementAction = createAction();
-  const decrementAction = createAction();
+  const incrementAction = createAction<void>();
+  const decrementAction = createAction<void>();
   const sumAction = createAction<number>();
   const subtractAction = createAction<number>();
-  const resetAction = createAction();
+  const resetAction = createAction<void>();
 
   const {
     incrementEffect,
diff --git a/packages/rx-effects/src/stateQuery.ts b/packages/rx-effects/src/stateQuery.ts
index d3fd942..25f663d 100644
--- a/packages/rx-effects/src/stateQuery.ts
+++ b/packages/rx-effects/src/stateQuery.ts
@@ -1,10 +1,10 @@
 import { Observable } from 'rxjs';
 import { map } from 'rxjs/operators';
 
-export type StateQuery<T> = Readonly<{
-  get: () => T;
-  value$: Observable<T>;
-}>;
+export type StateQuery<T> = {
+  readonly get: () => T;
+  readonly value$: Observable<T>;
+};
 
 export function mapStateQuery<T, R>(
   query: StateQuery<T>,
diff --git a/packages/rx-effects/src/stateStore.ts b/packages/rx-effects/src/stateStore.ts
index 394ecc3..3f27b23 100644
--- a/packages/rx-effects/src/stateStore.ts
+++ b/packages/rx-effects/src/stateStore.ts
@@ -3,25 +3,22 @@ import { distinctUntilChanged, map, shareReplay } from 'rxjs/operators';
 import { StateMutation } from './stateMutation';
 import { StateQuery } from './stateQuery';
 
-export type StateReader<State> = Readonly<
-  StateQuery<State> & {
-    select: <R>(
-      selector: (state: State) => R,
-      compare?: (v1: R, v2: R) => boolean,
-    ) => Observable<R>;
-    query: <R>(
-      selector: (state: State) => R,
-      compare?: (v1: R, v2: R) => boolean,
-    ) => StateQuery<R>;
-  }
->;
+export type StateReader<State> = StateQuery<State> & {
+  readonly select: <R>(
+    selector: (state: State) => R,
+    compare?: (v1: R, v2: R) => boolean,
+  ) => Observable<R>;
+
+  readonly query: <R>(
+    selector: (state: State) => R,
+    compare?: (v1: R, v2: R) => boolean,
+  ) => StateQuery<R>;
+};
 
-export type StateStore<State> = Readonly<
-  StateReader<State> & {
-    set: (state: State) => void;
-    update: (mutation: StateMutation<State>) => void;
-  }
->;
+export type StateStore<State> = StateReader<State> & {
+  readonly set: (state: State) => void;
+  readonly update: (mutation: StateMutation<State>) => void;
+};
 
 export function createStateStore<State>(
   initialState: State,
diff --git a/packages/rx-effects/src/stateUtils.ts b/packages/rx-effects/src/stateUtils.ts
index 40311ac..c63e5af 100644
--- a/packages/rx-effects/src/stateUtils.ts
+++ b/packages/rx-effects/src/stateUtils.ts
@@ -17,7 +17,7 @@ export function createUpdateStoreEffect<Event, State>(
 export function createResetStoreEffect<State>(
   store: StateStore<State>,
   nextState: State,
-): Effect<unknown> {
+): Effect<void> {
   return createEffect(() => store.set(nextState));
 }