如何完全关闭glog来运行go测试？

I'm writing test code for my code and would like to get 100% code coverage.

This implies testing corner cases that calls glog.Fatal() for instance.

So first thing I need is to disable any output by glog because I'm not testing glog. So I can run go test without generating files in /tmp or spittig messages to stderr.

The second thing I need is that a call to glog.Fatal() which calls os.Exit() doesn't interfere with running the test.

How could I achieve that ?

You should be able to achieve it by programming to the glog interface. I'm not sure what that is but it could look like

type Logger interface {
  Fatal()
  Info()
  // etc...
}

Then your packages/functions/structs etc, would have to require the interface opposed to including a global.

type SomeStruct struct {
  log Logger
}

Or on your top level modules:

func SomeFunc(log Logger) {}

Using an interface decouples your code from a loggers specific implementation.

In your unit tests you can create a test specific logger, which is a stub, or a mock.

type TestLogger struct {}
func (tl TestLogger) Fatal() {}
func (tl TestLogger) Info() {}
// etc....

Then your code has to be able to instantiate and configure the real Glog instance, in your production code. To test this, it should be as simple as encapsulating "creating" a Glog instance.

func NewLogger Logger {
  // configure `Glog` 
  // return `Glog`
}

This way you should be able to unit test the NewLogger configures a logger correctly without actually having to make calls to the logger.