added frontBack

Author: silphire

warmup1/frontBack.go

@@ -0,0 +1,11 @@
+package warmup1
+
+// https://codingbat.com/prob/p123384
+
+func frontBack(str string) string {
+	n := len(str)
+	if n == 1 {
+		return str
+	}
+	return str[n-1:n] + str[1:n-1] + str[0:1]
+}

warmup1/frontBack_test.go

@@ -0,0 +1,30 @@
+package warmup1
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestSwap(t *testing.T) {
+	actual := frontBack("back")
+	expected := "kacb"
+	if strings.Compare(expected, actual) != 0 {
+		t.Fatalf("expected \"%s\" but actual is \"%s\"", expected, actual)
+	}
+}
+
+func TestOneChar(t *testing.T) {
+	expected := frontBack("x")
+	actual := "x"
+	if strings.Compare(expected, actual) != 0 {
+		t.Fatalf("expected \"%s\" but actual is \"%s\"", expected, actual)
+	}
+}
+
+func TestOddChars(t *testing.T) {
+	actual := frontBack("abcde")
+	expected := "ebcda"
+	if strings.Compare(expected, actual) != 0 {
+		t.Fatalf("expected \"%s\" but actual is \"%s\"", expected, actual)
+	}
+}