feat(compiler-sfc): transform srcset (#501)

packages/compiler-sfc/__tests__/templateTransformSrcset.spec.ts

@@ -0,0 +1,31 @@
+import { generate, parse, transform } from '@vue/compiler-core'
+import { transformSrcset } from '../src/templateTransformSrcset'
+import { transformElement } from '../../compiler-core/src/transforms/transformElement'
+import { transformBind } from '../../compiler-core/src/transforms/vBind'
+
+function compileWithSrcset(template: string) {
+  const ast = parse(template)
+  transform(ast, {
+    nodeTransforms: [transformSrcset, transformElement],
+    directiveTransforms: {
+      bind: transformBind
+    }
+  })
+  return generate(ast, { mode: 'module' })
+}
+
+describe('compiler sfc: transform srcset', () => {
+  test('transform srcset', () => {
+    const result = compileWithSrcset(`
+			<img src="./logo.png" srcset="./logo.png"/>
+			<img src="./logo.png" srcset="./logo.png 2x"/>
+			<img src="./logo.png" srcset="./logo.png 2x"/>
+			<img src="./logo.png" srcset="./logo.png, ./logo.png 2x"/>
+			<img src="./logo.png" srcset="./logo.png 2x, ./logo.png"/>
+			<img src="./logo.png" srcset="./logo.png 2x, ./logo.png 3x"/>
+			<img src="./logo.png" srcset="./logo.png, ./logo.png 2x, ./logo.png 3x"/>
+		`)
+
+    expect(result.code).toMatchSnapshot()
+  })
+})