Add unit-testing exercise

unit-testing/go.mod

@@ -0,0 +1,3 @@
+module unit-testing
+
+go 1.22.2

unit-testing/main.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"math"
+	"os"
+	"strconv"
+)
+
+type Numbers interface {
+	int64 | float64 | int
+}
+
+func main() {
+	fmt.Print()
+	if len(os.Args) != 2 {
+		fmt.Println("Usage: ./sqrt 49")
+		os.Exit(1)
+	}
+	arg, err := strconv.Atoi(os.Args[1])
+	if err != nil {
+		log.Fatalf("Error occurred calculating square root: %v\n", err)
+	}
+
+	s := getSquareRoot(arg)
+	fmt.Println(s)
+}
+
+func getSquareRoot[T Numbers](n T) T {
+
+	squareRoot := math.Sqrt(float64(n))
+
+	return T(squareRoot)
+}