Golang: Can you wrap a Package in an Interface?

I'm writing a simple library to assist with common assertions.

type Test interface {
    Fatalf(string, ...interface{})
}

func IsTrue(statement bool, message string, test Test) {
    if !statement {
       test.Fatalf(message)
    }
}

I noticed that the log package actually has a compatible implementation of Fatalf(string, ...interface{}) and it'd be great if the IsTrue method could be invoked accordingly:

IsTrue(false, "false wasn't true", log)

But I get the error use of package log not in selector. Is there any way to use or wrap a package to make this pattern work or is this not possible?