Add useImageDimensions tests

src/useImageDimensions.test.ts

@@ -0,0 +1,157 @@
+import {useImageDimensions} from './useImageDimensions'
+import {act, renderHook} from '@testing-library/react-hooks'
+import {Image} from 'react-native'
+
+jest.mock('react-native', () => ({
+  Image: {
+    resolveAssetSource: jest.fn().mockReturnValue({width: 0, height: 0}),
+    getSize: jest.fn(),
+  },
+}))
+
+describe('useImageDimensions', () => {
+  describe('external images', () => {
+    const mockSource = {uri: 'test'}
+    const getSizeMock = Image.getSize as jest.Mock
+
+    it('should invoke getSize with with passed uri', () => {
+      renderHook(() => useImageDimensions(mockSource))
+
+      expect(getSizeMock).toBeCalledWith(
+        mockSource.uri,
+        expect.any(Function),
+        expect.any(Function),
+      )
+    })
+
+    it('should return error when cannot get image size', () => {
+      const error = new Error('Ops...')
+
+      getSizeMock.mockImplementationOnce((_, onSuccess, onError) => {
+        onError(error)
+      })
+
+      const {result} = renderHook(() => useImageDimensions(mockSource))
+
+      expect(result.current).toEqual({
+        loading: false,
+        error,
+      })
+    })
+
+    it('should return dimensions when successfully get image size', () => {
+      const width = 111
+      const height = 222
+      let emitOnSuccess = (() => {}) as (width: number, height: number) => void
+
+      getSizeMock.mockImplementationOnce((_, onSuccess) => {
+        emitOnSuccess = onSuccess
+      })
+
+      const {result} = renderHook(() => useImageDimensions(mockSource))
+
+      expect(result.current).toEqual({loading: true})
+
+      act(() => {
+        emitOnSuccess(width, height)
+      })
+
+      expect(result.current).toEqual({
+        loading: false,
+        dimensions: {width, height, aspectRatio: 0.5},
+      })
+    })
+
+    it('should update image size when source change', () => {
+      let emitOnSuccess = (() => {}) as (width: number, height: number) => void
+
+      getSizeMock.mockImplementation((_, onSuccess) => {
+        emitOnSuccess = onSuccess
+      })
+
+      const {result, rerender} = renderHook(
+        (props) => useImageDimensions(props.source),
+        {initialProps: {source: mockSource}},
+      )
+
+      expect(result.current).toEqual({loading: true})
+
+      act(() => emitOnSuccess(1, 2))
+
+      expect(result.current).toEqual({
+        loading: false,
+        dimensions: {width: 1, height: 2, aspectRatio: 0.5},
+      })
+
+      rerender({source: {uri: 'new-uri'}})
+
+      expect(result.current).toEqual({loading: true})
+
+      act(() => emitOnSuccess(3, 4))
+
+      expect(result.current).toEqual({
+        loading: false,
+        dimensions: {width: 3, height: 4, aspectRatio: 0.75},
+      })
+    })
+  })
+
+  describe('bundled up images', () => {
+    const mockImage = 0 // typeof require('img.png') === 'number'
+    const getResolveAssetSource = Image.resolveAssetSource as jest.Mock
+
+    it('should invoke resolveAssetSource with passed image', () => {
+      renderHook(() => useImageDimensions(mockImage))
+
+      expect(getResolveAssetSource).toBeCalledWith(mockImage)
+    })
+
+    it('should return image dimensions', () => {
+      const width = 111
+      const height = 222
+
+      getResolveAssetSource.mockReturnValueOnce({width, height})
+
+      const {result} = renderHook(() => useImageDimensions(mockImage))
+
+      expect(result.current).toEqual({
+        loading: false,
+        dimensions: {
+          width,
+          height,
+          aspectRatio: 0.5,
+        },
+      })
+    })
+
+    it('should return an error when unexpected error happened', () => {
+      const error = new Error('Cannot find image')
+
+      getResolveAssetSource.mockImplementationOnce(() => {
+        throw error
+      })
+
+      const {result} = renderHook(() => useImageDimensions(mockImage))
+
+      expect(result.current).toEqual({
+        loading: false,
+        error,
+      })
+    })
+  })
+
+  it('should return an error when pass non image', () => {
+    const nonImage = 'Ops )))'
+    const {result} = renderHook(() =>
+      useImageDimensions(
+        // @ts-expect-error - non image
+        nonImage,
+      ),
+    )
+
+    expect(result.current).toEqual({
+      loading: false,
+      error: expect.any(Error),
+    })
+  })
+})