chore(image-shrink): add fallback test

packages/image-shrink/src/utils/render/fallback.test.ts

@@ -0,0 +1,42 @@
+/// <reference types="vite/client" />
+import { describe, expect, it } from 'vitest'
+import { fallback } from './fallback'
+import { loadImageAsBlob } from '../../test/helpers/loadImageAsBlob'
+import { imageLoader } from '../../utils/image/imageLoader'
+
+describe('fallback', () => {
+  it('should work', async () => {
+    const originalFile = await loadImageAsBlob(
+      () => import('../../test/samples/2000x2000.jpeg')
+    )
+    const image = await imageLoader(URL.createObjectURL(originalFile))
+    URL.revokeObjectURL(image.src)
+
+    const canvas = await fallback({
+      img: image,
+      sourceW: image.width,
+      targetW: 100,
+      targetH: 100,
+      step: 0.71
+    })
+
+    expect(canvas.width).toBe(100)
+  })
+
+  it('should throw if not supported', async () => {
+    const originalFile = await loadImageAsBlob(
+      () => import('../../test/samples/2000x2000.jpeg')
+    )
+    const image = await imageLoader(URL.createObjectURL(originalFile))
+    URL.revokeObjectURL(image.src)
+
+    const promise = fallback({
+      img: image,
+      sourceW: image.width,
+      targetW: 65535 + 1,
+      targetH: 65535 + 1,
+      step: 0.71
+    })
+    expect(promise).rejects.toThrow('Not supported')
+  })
+})

packages/image-shrink/src/utils/render/fallback.ts

@@ -59,14 +59,17 @@ export const fallback = ({
   const steps = calcShrinkSteps({ sourceW, targetW, targetH, step })
 
   return steps.reduce(
-    (chain, [w, h]) => {
+    (chain, [w, h], idx) => {
       return chain.then((canvas) => {
-        return (
-          testCanvasSize(w, h)
-            .then(() => canvasResize(canvas, w, h))
-            // Here we assume that at least one step will be supported and HTMLImageElement will be converted to HTMLCanvasElement
-            .catch(() => canvas as unknown as HTMLCanvasElement)
-        )
+        return testCanvasSize(w, h)
+          .then(() => canvasResize(canvas, w, h))
+          .catch(() => {
+            if (idx === steps.length - 1) {
+              // If the last step is failed then we assume that we can't shrink the image at all
+              throw new Error('Not supported')
+            }
+            return canvas as unknown as HTMLCanvasElement
+          })
       })
     },
     Promise.resolve(img as HTMLCanvasElement | HTMLImageElement)