test: add unit test for part two

internal/2018/DayFour/code_test.go

@@ -2,8 +2,7 @@ package dayfour
 
 import "testing"
 
-func TestPartOne(t *testing.T) {
-	input := []string{
+var testInput = []string{
 	"[1518-11-01 00:00] Guard #10 begins shift",
 	"[1518-11-01 00:05] falls asleep",
 	"[1518-11-01 00:25] wakes up",
@@ -22,9 +21,19 @@ func TestPartOne(t *testing.T) {
 	"[1518-11-05 00:45] falls asleep",
 	"[1518-11-05 00:55] wakes up",
 }
+
+func TestPartOne(t *testing.T) {
 	expected := 240
-	got := PartOne(input)
+	got := PartOne(testInput)
 	if got != expected {
 		t.Errorf("PartOne() = %d, want %d", got, expected)
 	}
 }
+
+func TestPartTwo(t *testing.T) {
+	expected := 4455
+	got := PartTwo(testInput)
+	if got != expected {
+		t.Errorf("PartTwo() = %d, want %d", got, expected)
+	}
+}