istanbulOptions does not accpect js and ts extension

[koushikdutta]

I have tried include ts extension with this plugin. But not sure why it's not happening. Following ways I have tried...

mocha_istanbul: {
            test: {
                src: [
                    './src/**/*.test.js',
                    './src/**/*.test.ts',
                ],
                options: {
                    coverage: true,
                    coverageFolder: './reports',
                    mochaOptions: ['-r', './babel-register.js'],
                    print: 'both',
                    root: './src',
                    istanbulOptions: ['--extension', '[".js", ".ts"]'],
                    reportFormats: ['cobertura', 'lcov']
                }
            }
        }