-cover to generate coverage information¶%goflags -cover
%goflags=["-cover"]
%goflags
%goflags=["-cover"]
// Clear %goflags
%goflags ""
%goflags=[]
%goflags -cover
%goflags=["-cover"]
GOCOVERDIR directory to hold coverage information¶%env GOCOVERDIR /tmp/gonb_examples_test_goflags_cover
!mkdir -p $GOCOVERDIR ; rm -f ${GOCOVERDIR}/*
Set: GOCOVERDIR="/tmp/gonb_examples_test_goflags_cover"
func A() {
fmt.Println("A")
}
func B() {
fmt.Println("B")
}
%%
A()
A
We expect that function A has full coverage, and function B has 0% coverage, since it was not called.
!go tool covdata func -i "${GOCOVERDIR}"
gonb_a636feef/main.go:8: A 100.0% gonb_a636feef/main.go:12: B 0.0% gonb_a636feef/main.go:17: main 100.0% total (statements) 75.0%
go build to inspect its output¶This can be achieved by manually running it, independent of GoNB, simply using it's ability of running shell commands in the temporary directory.
First we clear the cache of GoNB, using %reset and then we create a small program to analyse if variables escape to heap (Go's garbage collection flag -gcflag=-m).
%reset
* State reset: all memorized declarations discarded.
type Point struct{ X, Y float64}
func (p *Point) ManhattanLen() float64 {
return p.X + p.Y
}
%%
p := Point{3,4}
fmt.Println(p.ManhattanLen())
7
Display optimization strategy of the code:
!*go build -gcflags=-m
# gonb_a636feef ./main.go:10:6: can inline (*Point).ManhattanLen ./main.go:16:12: inlining call to flag.Parse ./main.go:18:27: inlining call to (*Point).ManhattanLen ./main.go:18:12: inlining call to fmt.Println ./main.go:10:7: p does not escape ./main.go:18:12: ... argument does not escape ./main.go:18:27: ~r0 escapes to heap