test: add image resolver API test case for Wasm

...and add pixels diff.

__test__/index.spec.ts

@@ -10,15 +10,15 @@ import { Resvg, renderAsync } from '../index'
 import { jimpToRgbaPixels } from './helper'
 
 test('Use href to load a JPG image without alpha', async (t) => {
+  const imgUrl = 'http://tva2.sinaimg.cn/crop.0.0.250.250.80/534b48acjw8ehw72edguyj206y06yq32.jpg'
   const svg = `<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
-  <image href="http://tva2.sinaimg.cn/crop.0.0.250.250.80/534b48acjw8ehw72edguyj206y06yq32.jpg" width="80" height="80"/>
+  <image href="${imgUrl}" width="80" height="80"/>
 </svg>`
-  const opts = {
+  const resvg = new Resvg(svg, {
     font: {
       loadSystemFonts: false,
     },
-  }
-  const resvg = new Resvg(svg, opts)
+  })
   const resolved = await Promise.all(
     resvg.imagesToResolve().map(async (url) => {
       console.info('image url', url)
@@ -37,10 +37,18 @@ test('Use href to load a JPG image without alpha', async (t) => {
     }
   }
   const pngData = resvg.render()
-  const pngBuffer = pngData.asPng()
+  const resvgPngBuffer = pngData.asPng()
+  const result1 = await jimp.read(resvgPngBuffer)
 
-  const result = await jimp.read(pngBuffer)
-  t.is(result.hasAlpha(), false)
+  const jimpImg = await fetch(imgUrl)
+  const jimpBuffer = await jimpImg.arrayBuffer()
+  const result2 = await jimp.read(jimpBuffer)
+
+  const r1 = new jimp({ data: result1.bitmap.data, width: pngData.width, height: pngData.height })
+  const r2 = new jimp({ data: result2.bitmap.data, width: result2.bitmap.width, height: result2.bitmap.height })
+
+  t.is(result1.hasAlpha(), false)
+  t.is(jimp.diff(r1, r2, 0.01).percent, 0) // 0 means similar, 1 means not similar
 })
 
 test('svg to RGBA pixels Array', async (t) => {

__test__/wasm.spec.ts

@@ -4,6 +4,7 @@ import { join } from 'path'
 
 import test from 'ava'
 import jimp from 'jimp-compact'
+import fetch from 'node-fetch'
 
 import { Resvg, initWasm } from '../wasm'
 
@@ -14,6 +15,44 @@ test.before(async () => {
   await initWasm(fs.readFile(join(__dirname, '../wasm/index_bg.wasm')))
 })
 
+test('Use href to load a JPG image without alpha', async (t) => {
+  const imgUrl = 'http://tva2.sinaimg.cn/crop.0.0.250.250.80/534b48acjw8ehw72edguyj206y06yq32.jpg'
+  const svg = `<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+  <image href="${imgUrl}" width="80" height="80"/>
+</svg>`
+  const resvg = new Resvg(svg)
+  const resolved = await Promise.all(
+    resvg.imagesToResolve().map(async (url) => {
+      console.info('image url', url)
+      const img = await fetch(url)
+      const buffer = await img.arrayBuffer()
+      return {
+        url,
+        buffer: Buffer.from(buffer),
+      }
+    }),
+  )
+  if (resolved.length > 0) {
+    for (const result of resolved) {
+      const { url, buffer } = result
+      resvg.resolveImage(url, buffer)
+    }
+  }
+  const pngData = resvg.render()
+  const resvgPngBuffer = Buffer.from(pngData.asPng())
+  const result1 = await jimp.read(resvgPngBuffer)
+
+  const jimpImg = await fetch(imgUrl)
+  const jimpBuffer = Buffer.from(await jimpImg.arrayBuffer())
+  const result2 = await jimp.read(jimpBuffer)
+
+  const r1 = new jimp({ data: result1.bitmap.data, width: pngData.width, height: pngData.height })
+  const r2 = new jimp({ data: result2.bitmap.data, width: result2.bitmap.width, height: result2.bitmap.height })
+
+  t.is(result1.hasAlpha(), false)
+  t.is(jimp.diff(r1, r2, 0.01).percent, 0) // 0 means similar, 1 means not similar
+})
+
 test('svg to RGBA pixels Array', async (t) => {
   const svg = `<svg width="10px" height="5px" viewBox="0 0 10 5" version="1.1" xmlns="http://www.w3.org/2000/svg">
     <rect fill="red" x="0" y="0" width="5" height="5"></rect>