Another small one on time precision that I’ve noticed.
package main
import (
"fmt"
"math"
"time"
)
func main() {
now := time.Now().Add(time.Hour)
seconds = time.Now().Sub(now).Seconds()
fmt.Println(int(seconds))
fmt.Println(int(math.Floor(seconds)))
}
Line 12 will print -3599, line 13 will print -3600 (tested on Ubuntu). So watch out when converting the number of seconds to an integer, you might not always get what you need.
Unit tests were needed on a new project I’m working on and a few weeks ago I wrote some. Last week, a colleague wrote some more, and when he ran all of them, mine were failing. Same code base, up to date, same tests. On my machine they were still passing. We jumped on the situation and saw math.Floor was giving a result on my machine, which runs on Ubuntu, and another one on his, on Windows.
The code is larger, but I’ve extracted and adapted what’s needed:
package main
import (
"time"
"math"
)
func main() {
datetime := time.Now().Add(time.Hour * 24 * 7 * 4 * 12 * 3)
seconds := -1 * int(time.Now().Sub(datetime).Seconds())
a := 29030400
x := float64(seconds)/float64(a)
println("input:", x, "floor:", math.Floor(x))
}
Result on Ubuntu:
input: +3.000000e+000 floor: +2.000000e+000
Result on Windows:
input: +3.000000e+000 floor: +3.000000e+000