diff --git a/internal/input/input_test.go b/internal/input/input_test.go
new file mode 100644
index 0000000..68366fd
--- /dev/null
+++ b/internal/input/input_test.go
@@ -0,0 +1,39 @@
+package input
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestToIntegers(t *testing.T) {
+	var tests = []struct {
+		name string
+		in   []string
+		want []int
+	}{
+		{
+			name: "empty case",
+			in:   []string{},
+			want: []int{},
+		},
+		{
+			name: "single case",
+			in:   []string{"0"},
+			want: []int{0},
+		},
+		{
+			name: "multiple case",
+			in:   []string{"0", "1", "2"},
+			want: []int{0, 1, 2},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := ToIntegers(tt.in)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("got %q, wanted %q", got, tt.want)
+			}
+		})
+	}
+}