Add types for @testing-library/react-hooks (#38715)

types/testing-library__react-hooks/index.d.ts

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+// Type definitions for @testing-library/react-hooks 2.0
+// Project: https://github.com/testing-library/react-hooks-testing-library
+// Definitions by: Michael Peyper <https://github.com/mpeyper>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 3.0
+
+import { ComponentType } from 'react';
+export { act } from 'react-test-renderer';
+
+export interface RenderHookOptions<P> {
+    initialProps?: P;
+    wrapper?: React.ComponentType;
+}
+
+export interface HookResult<R> {
+    readonly current: R;
+    readonly error: Error;
+}
+
+export interface RenderHookResult<P, R> {
+    readonly result: HookResult<R>;
+    readonly waitForNextUpdate: () => Promise<void>;
+    readonly unmount: () => boolean;
+    readonly rerender: (newProps?: P) => void;
+}
+
+export function renderHook<P, R>(callback: (props: P) => R, options?: RenderHookOptions<P>): RenderHookResult<P, R>;

types/testing-library__react-hooks/testing-library__react-hooks-tests.ts

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+import { useState } from 'react';
+import { renderHook, act } from '@testing-library/react-hooks';
+
+const useHook = (initialValue: number) => {
+    const [value, setValue] = useState(initialValue);
+    return { value, setValue };
+};
+
+function checkTypesWithNoInitialProps() {
+    const { result, unmount, rerender } = renderHook(() => useHook(0));
+
+    // check types
+    const _result: {
+        current: {
+            value: number;
+            setValue: (_: number) => void;
+        };
+    } = result;
+    const _unmount: () => boolean = unmount;
+    const _rerender: () => void = rerender;
+}
+
+function checkTypesWithInitialProps() {
+    const { result, unmount, rerender } = renderHook(({ value }) => useHook(value), {
+        initialProps: { value: 10 },
+    });
+
+    // check types
+    const _result: {
+        current: {
+            value: number;
+            setValue: (_: number) => void;
+        };
+    } = result;
+    const _unmount: () => boolean = unmount;
+    const _rerender: (_?: { value: number }) => void = rerender;
+}
+
+function checkTypesWhenHookReturnsUndefined() {
+    renderHook(() => {});
+}
+
+function checkTypesWithError() {
+    const { result } = renderHook(() => useHook(0));
+
+    // check types
+    const _result: {
+        error: Error;
+    } = result;
+}
+
+async function checkTypesForWaitForNextUpdate() {
+    const { waitForNextUpdate } = renderHook(() => {});
+
+    await waitForNextUpdate();
+
+    // check type
+    const _waitForNextUpdate: () => Promise<void> = waitForNextUpdate;
+}
+
+function checkTypesWithUndefinedResult() {
+    act(() => undefined);
+}
+
+function checkTypesWithVoidResult() {
+    act(() => {});
+}
+
+function checkTypesWithPromiseResult() {
+    act(() => Promise.resolve());
+}

types/testing-library__react-hooks/tsconfig.json

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+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": ["es6", "dom"],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "strictFunctionTypes": true,
+        "baseUrl": "../",
+        "typeRoots": ["../"],
+        "target": "es6",
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true,
+        "paths": {
+            "@testing-library/react-hooks": ["testing-library__react-hooks"]
+        }
+    },
+    "files": ["index.d.ts", "testing-library__react-hooks-tests.ts"]
+}

types/testing-library__react-hooks/tslint.json

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+{
+    "extends": "dtslint/dt.json"
+}