feat: support run single test

test/unit/selector.js

@@ -0,0 +1,19 @@
+/**
+ * 运行单个测试文件
+ */
+
+const fs = require('fs');
+const inquirer = require('inquirer');
+const path = require('path');
+const shell = require('shelljs');
+const files = fs.readdirSync(path.resolve(__dirname, './specs'));
+
+inquirer.prompt([{
+  type: 'list',
+  name: 'select',
+  message: '请选择要运行的测试文件：',
+  choices: files
+}], (result) => {
+  const file = result.select.replace('.spec.js', '');
+  shell.exec('karma start test/unit/karma.conf.js --color alway --file ' + file);
+});