go/src/testing/newcover.go

var cover2 …

// registerCover2 is invoked during "go test -cover" runs.
// It is used to record a 'tear down' function
// (to be called when the test is complete) and the coverage mode.
func registerCover2(mode string, tearDown func(coverprofile string, gocoverdir string) (string, error), snapcov func() float64) { … }

// coverReport2 invokes a callback in _testmain.go that will
// emit coverage data at the point where test execution is complete,
// for "go test -cover" runs.
func coverReport2() { … }

// coverage2 returns a rough "coverage percentage so far"
// number to support the testing.Coverage() function.
func coverage2() float64 { … }