feat(entity): strengthen typing of getInitialState (#4819)

Closes #4422

Author: timdeschryver

modules/entity/spec/types/entity_state.types.spec.ts

@@ -0,0 +1,63 @@
+import { expecter } from 'ts-snippet';
+import { compilerOptions } from './utils';
+
+describe('EntityState Types', () => {
+  const expectSnippet = expecter(
+    (code) => `
+        import { EntityState, createEntityAdapter, EntityAdapter } from '@ngrx/entity';
+
+        interface Book {
+          id: string;
+          title: string;
+        }
+
+        interface BookState extends EntityState<Book> {
+          selectedBookId: string | null;
+        }
+
+        export const adapter: EntityAdapter<Book> = createEntityAdapter<Book>();
+        ${code}
+      `,
+    compilerOptions()
+  );
+
+  describe('getInitialState', () => {
+    it('can set the initial state', () => {
+      expectSnippet(`
+        export const initialState: BookState = adapter.getInitialState({
+          selectedBookId: '1',
+        });
+
+      `).toSucceed();
+    });
+
+    it('can set the initial state with additional properties', () => {
+      expectSnippet(`
+        export const initialState: BookState = adapter.getInitialState({
+          selectedBookId: '1',
+        });
+
+      `).toSucceed();
+    });
+
+    it('throws when setting the initial state with unknown properties', () => {
+      expectSnippet(`
+        export const initialState: BookState = adapter.getInitialState({
+          selectedBookId: '1',
+          otherProperty: 'value',
+        });
+      `).toFail(
+        /Object literal may only specify known properties, and 'otherProperty' does not exist in type 'Omit<BookState, keyof EntityState<T>>'/i
+      );
+    });
+
+    it('can set the initial state with unknown properties when the state is untyped', () => {
+      expectSnippet(`
+        export const initialState = adapter.getInitialState({
+          selectedBookId: '1',
+          otherProperty: 'value',
+        });
+      `).toSucceed();
+    });
+  });
+});

modules/entity/src/entity_state.ts

@@ -9,9 +9,9 @@ export function getInitialEntityState<V>(): EntityState<V> {
 
 export function createInitialStateFactory<V>() {
   function getInitialState(): EntityState<V>;
-  function getInitialState<S extends object>(
-    additionalState: S
-  ): EntityState<V> & S;
+  function getInitialState<S extends EntityState<V>>(
+    additionalState: Omit<S, keyof EntityState<V>>
+  ): S;
   function getInitialState(additionalState: any = {}): any {
     return Object.assign(getInitialEntityState(), additionalState);
   }

modules/entity/src/models.ts

@@ -110,7 +110,9 @@ export interface EntityAdapter<T> extends EntityStateAdapter<T> {
   selectId: IdSelector<T>;
   sortComparer: false | Comparer<T>;
   getInitialState(): EntityState<T>;
-  getInitialState<S extends object>(state: S): EntityState<T> & S;
+  getInitialState<S extends EntityState<T>>(
+    state: Omit<S, keyof EntityState<T>>
+  ): S;
   getSelectors(): EntitySelectors<T, EntityState<T>>;
   getSelectors<V>(
     selectState: (state: V) => EntityState<T>

modules/store/src/selector.ts

@@ -73,7 +73,7 @@ export function defaultMemoize(
   isResultEqual = isEqualCheck
 ): MemoizedProjection {
   let lastArguments: null | IArguments = null;
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any, , , , ,
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
   let lastResult: any = null;
   let overrideResult: any;