fix: camel case match (umijs#632)

* fix: camel case match

* test: update test case

src/Plugin.js

@@ -2,8 +2,11 @@ import { join } from 'path';
 import { addSideEffect, addDefault, addNamed } from '@babel/helper-module-imports';
 
 function transCamel(_str, symbol) {
-  const str = _str[0].toLowerCase() + _str.substr(1);
-  return str.replace(/([A-Z])/g, $1 => `${symbol}${$1.toLowerCase()}`);
+  // e.g. QRCode
+  // First match: QR
+  // Second match: Code
+  const cells = _str.match(/([A-Z]+(?=[A-Z]))|([A-Z]?[^A-Z]+)/g) || [];
+  return cells.map(c => c.toLowerCase()).join(symbol);
 }
 
 function winPath(path) {

test/fixtures/qr-code/actual.js

@@ -0,0 +1,8 @@
+import { QRCode } from 'antd';
+
+switch(QRCode){
+  case QRCode:
+    console.log('foo');
+  default:
+    console.log('bar')
+}

test/fixtures/qr-code/expected.js

@@ -0,0 +1,7 @@
+import _QRCode from "antd/lib/qr-code";
+switch (_QRCode) {
+  case _QRCode:
+    console.log('foo');
+  default:
+    console.log('bar');
+}