tests for rot13 algorithm

Author: Michele Caci

ciphers/Rot13.go renamed to ciphers/rot13/rot13.go

@@ -1,8 +1,7 @@
-package main
+package rot13
 
 import (
 	"bytes"
-	"fmt"
 	"strings"
 )
 
@@ -24,11 +23,4 @@ func rot13(input string) string {
 		outputBuffer.WriteString(string(newByte))
 	}
 	return outputBuffer.String()
-
-}
-func main() {
-	cleartext := "We'll just make him an offer he can't refuse... tell me you get the pop culture reference"
-	encrypted := rot13(cleartext)
-	decrypted := rot13(encrypted)
-	fmt.Printf("Cleartext: %v\nencrypted: %v\ndecrypted: %v\n", cleartext, encrypted, decrypted)
 }

ciphers/rot13/rot13_test.go

@@ -0,0 +1,70 @@
+package rot13
+
+import (
+	"testing"
+)
+
+var rot13TestData = []struct {
+	description string
+	input       string
+	expected    string
+}{
+	{
+		"Basic rotation with letter 'a' gives 'n",
+		"a",
+		"n",
+	},
+	{
+		"Rotation with wrapping around alphabet on letter 'z' gives 'm'",
+		"z",
+		"m",
+	},
+	{
+		"Rotation on 'hello world'",
+		"hello world",
+		"uryyb jbeyq",
+	},
+	{
+		"Rotation on the rotation of 'hello world' gives 'hello world' back",
+		"uryyb jbeyq",
+		"hello world",
+	},
+	{
+		"Full sentence rotation",
+		"the quick brown fox jumps over the lazy dog.",
+		"gur dhvpx oebja sbk whzcf bire gur ynml qbt.",
+	},
+	{
+		"Sentence from Rot13.go main function",
+		"we'll just make him an offer he can't refuse... tell me you get the pop culture reference",
+		"jr'yy whfg znxr uvz na bssre ur pna'g ershfr... gryy zr lbh trg gur cbc phygher ersrerapr",
+	},
+}
+
+func TestRot13Encrypt(t *testing.T) {
+	for _, test := range rot13TestData {
+		t.Run(test.description, func(t *testing.T) {
+			input := test.input
+			expected := test.expected
+			assertRot13Output(t, input, expected)
+		})
+	}
+}
+
+func TestRot13Decrypt(t *testing.T) {
+	for _, test := range rot13TestData {
+		t.Run(test.description, func(t *testing.T) {
+			input := test.expected
+			expected := test.input
+			assertRot13Output(t, input, expected)
+		})
+	}
+}
+
+func assertRot13Output(t *testing.T, input, expected string) {
+	actual := rot13(input)
+	if actual != expected {
+		t.Fatalf("With input string '%s' was expecting '%s' but actual was '%s'",
+			input, expected, actual)
+	}
+}