Added react-testing-library tests

Author: mpeyper

test/testHook.test.js

@@ -0,0 +1,83 @@
+import React, { useState, useEffect } from 'react'
+import { testHook, cleanup, act } from 'src'
+
+describe('testHook tests', () => {
+  afterEach(cleanup)
+
+  test('testHook calls the callback', () => {
+    const spy = jest.fn()
+    testHook(spy)
+    expect(spy).toHaveBeenCalledTimes(1)
+  })
+
+  test('confirm we can safely call a React Hook from within the callback', () => {
+    testHook(() => useState())
+  })
+
+  test('returns a function to unmount component', () => {
+    let isMounted
+    const { unmount } = testHook(() => {
+      useEffect(() => {
+        isMounted = true
+        return () => {
+          isMounted = false
+        }
+      })
+    })
+    expect(isMounted).toBe(true)
+    unmount()
+    expect(isMounted).toBe(false)
+  })
+
+  test('returns a function to rerender component', () => {
+    let renderCount = 0
+    const { rerender } = testHook(() => {
+      useEffect(() => {
+        renderCount++
+      })
+    })
+
+    expect(renderCount).toBe(1)
+    rerender()
+    expect(renderCount).toBe(2)
+  })
+
+  test('accepts wrapper option to wrap rendered hook with', () => {
+    const ctxA = React.createContext()
+    const ctxB = React.createContext()
+    const useHook = () => {
+      return React.useContext(ctxA) * React.useContext(ctxB)
+    }
+    let actual
+    testHook(
+      () => {
+        actual = useHook()
+      },
+      {
+        // eslint-disable-next-line react/display-name
+        wrapper: (props) => (
+          <ctxA.Provider value={3}>
+            <ctxB.Provider value={4} {...props} />
+          </ctxA.Provider>
+        )
+      }
+    )
+    expect(actual).toBe(12)
+  })
+
+  test('returns result ref with latest result from hook execution', () => {
+    function useCounter({ initialCount = 0, step = 1 } = {}) {
+      const [count, setCount] = React.useState(initialCount)
+      const increment = () => setCount((c) => c + step)
+      const decrement = () => setCount((c) => c - step)
+      return { count, increment, decrement }
+    }
+
+    const { result } = testHook(useCounter)
+    expect(result.current.count).toBe(0)
+    act(() => {
+      result.current.increment()
+    })
+    expect(result.current.count).toBe(1)
+  })
+})