fix: remove space after selector when inserting scoped attribute

close vue-loader/#1370

Author: yyx990803

lib/stylePlugins/scoped.ts

@@ -22,7 +22,7 @@ export default postcss.plugin('add-id', (options: any) => (root: Root) => {
     }
     node.selector = selectorParser((selectors: any) => {
       selectors.each((selector: any) => {
-        let node = null
+        let node: any = null
         selector.each((n: any) => {
           // ">>>" combinator
           if (n.type === 'combinator' && n.value === '>>>') {
@@ -43,12 +43,15 @@ export default postcss.plugin('add-id', (options: any) => (root: Root) => {
             node = n
           }
         })
-        selector.insertAfter(
-          node,
-          selectorParser.attribute({
-            attribute: id
-          })
-        )
+        if (node) {
+          node.spaces.after = ''
+          selector.insertAfter(
+            node,
+            selectorParser.attribute({
+              attribute: id
+            })
+          )
+        }
       })
     }).processSync(node.selector)
   })

test/stylePluginScoped.spec.ts

@@ -0,0 +1,12 @@
+import { compileStyle } from '../lib/compileStyle'
+
+// vue-loader/#1370
+test('spaces after selector', () => {
+  const { code } = compileStyle({
+    source: `.foo , .bar { color: red; }`,
+    filename: 'test.css',
+    id: 'test'
+  })
+
+  expect(code).toMatch(`.foo[test], .bar[test] { color: red;`)
+})