Error:A problem occurred configuring project ':app'.
> Could not resolve all dependencies for configuration ':app:_debugUnitTestCompile'.
> Could not resolve junit:junit:4.12.
Required by:
BJ:app:unspecified
> Could not resolve junit:junit:4.12.
> Could not get resource 'https://jcenter.bintray.com/junit/junit/4.12/junit-4.12.pom'.
> Failure initializing default system SSL context

 build.gradle 文件:
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.1.1'
compile 'com.android.support:design:23.1.1'
}

当我删除 build.gradle 文件中的 

testCompile 'junit:junit:4.12'后  运行项目,会出现一直 build  runnin中   如果继续操作工具会出现电脑系统死机的情况, 请问大神这是怎么回事