fix(sfc): inherit parent scopeId on child rooot (#756)

packages/server-renderer/__tests__/renderToString.spec.ts

@@ -562,7 +562,7 @@ describe('ssr: renderToString', () => {
       }
 
       expect(await renderToString(h(Parent))).toBe(
-        `<div data-v-child><span data-v-test data-v-child-s>slot</span></div>`
+        `<div data-v-test data-v-child><span data-v-test data-v-child-s>slot</span></div>`
       )
     })
   })

packages/server-renderer/__tests__/ssrRenderAttrs.spec.ts

@@ -26,6 +26,14 @@ describe('ssr: renderAttrs', () => {
     ).toBe(` id="foo" title="bar"`)
   })
 
+  test('empty value attrs', () => {
+    expect(
+      ssrRenderAttrs({
+        'data-v-abc': ''
+      })
+    ).toBe(` data-v-abc`)
+  })
+
   test('escape attrs', () => {
     expect(
       ssrRenderAttrs({

packages/server-renderer/src/helpers/ssrRenderAttrs.ts

@@ -53,7 +53,9 @@ export function ssrRenderDynamicAttr(
   if (isBooleanAttr(attrKey)) {
     return value === false ? `` : ` ${attrKey}`
   } else if (isSSRSafeAttrName(attrKey)) {
-    return ` ${attrKey}="${escapeHtml(value)}"`
+    return value === ''
+      ? ` ${attrKey}`
+      : ` ${attrKey}="${escapeHtml(value)}"`
   } else {
     console.warn(
       `[@vue/server-renderer] Skipped rendering unsafe attribute name: ${attrKey}`