Initial code

main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	sponge_case "sponge-case/sponge-case"
+)
+
+func main() {
+	if len(os.Args) == 2 {
+		applyToArgs()
+	} else {
+		applyToStdin()
+	}
+}
+
+func applyToStdin() {
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		fmt.Println(sponge_case.ApplyStr(scanner.Text()))
+	}
+	if err := scanner.Err(); err != nil {
+		fmt.Println(err)
+	}
+}
+
+func applyToArgs() {
+	fmt.Println(sponge_case.ApplyStr(os.Args[1]))
+}

sponge-case/sponge-case.go

@@ -0,0 +1,23 @@
+package sponge_case
+
+import (
+	"math/rand"
+	"unicode"
+)
+
+func ApplyStr(in string) string {
+	out := make([]rune, len(in))
+	var newChar rune
+
+	for pos, char := range []rune(in) {
+		toUpper := rand.Float32() > 0.5
+		if toUpper {
+			newChar = unicode.ToUpper(char)
+		} else {
+			newChar = unicode.ToLower(char)
+		}
+		out[pos] = newChar
+	}
+
+	return string(out)
+}

sponge-case/sponge-case_test.go

@@ -0,0 +1,10 @@
+package sponge_case
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestApplyStr(t *testing.T) {
+	fmt.Println(ApplyStr("Das ist wirklich nicht witzig!"))
+}