Add simple caesar cipher using go

Cryptography/src/Caesar/Simple_Caesar/caesarcrypto.go

@@ -0,0 +1,35 @@
+package crypto
+
+import (
+	"strings"
+)
+
+// CaesarCipherEncode ...
+func CaesarCipherEncode(input string, shift int) string {
+	var output strings.Builder
+	for _, c := range input {
+		var lowercaseFlag bool
+		if c >= 97 && c <= 122 {
+			c -= 32
+			lowercaseFlag = true
+		}
+		if c >= 65 && c <= 90 {
+			c += rune(shift)
+			if c > 90 {
+				c = 65 + (c-90-1)%26
+			} else if c < 65 {
+				c = 90 - (65-c-1)%26
+			}
+		}
+		if lowercaseFlag {
+			c += 32
+		}
+		output.WriteRune(c)
+	}
+	return output.String()
+}
+
+// CaesarCipherDecode ...
+func CaesarCipherDecode(input string, shift int) string {
+	return CaesarCipherEncode(input, -shift)
+}

Cryptography/src/Caesar/Simple_Caesar/caesarcrypto_test.go

@@ -0,0 +1,64 @@
+package crypto
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_CaesarCipherEncode(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		shift    int
+		expected string
+	}{
+		{
+			name:     "Encode 1",
+			input:    "A quIck BrOwN FoX jUMps OvEr thE lAzY DoG 123",
+			shift:    3,
+			expected: "D txLfn EuRzQ IrA mXPsv RyHu wkH oDcB GrJ 123",
+		},
+		{
+			name:     "Encode 2",
+			input:    "A quIck BrOwN FoX jUMps OvEr thE lAzY DoG 123",
+			shift:    -3,
+			expected: "X nrFzh YoLtK ClU gRJmp LsBo qeB iXwV AlD 123",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := CaesarCipherEncode(tt.input, tt.shift); !reflect.DeepEqual(got, tt.expected) {
+				t.Errorf("CaesarCipherEncode() = %v, expected %v", got, tt.expected)
+			}
+		})
+	}
+}
+
+func Test_CaesarCipherDecode(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		shift    int
+		expected string
+	}{
+		{
+			name:     "Decode 1",
+			input:    "D txLfn EuRzQ IrA mXPsv RyHu wkH oDcB GrJ 123",
+			shift:    3,
+			expected: "A quIck BrOwN FoX jUMps OvEr thE lAzY DoG 123",
+		},
+		{
+			name:     "Decode 2",
+			input:    "X nrFzh YoLtK ClU gRJmp LsBo qeB iXwV AlD 123",
+			shift:    -3,
+			expected: "A quIck BrOwN FoX jUMps OvEr thE lAzY DoG 123",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := CaesarCipherDecode(tt.input, tt.shift); !reflect.DeepEqual(got, tt.expected) {
+				t.Errorf("CaesarCipherDecode() = %v, expected %v", got, tt.expected)
+			}
+		})
+	}
+}