test: add unit test for part one

internal/2015/DayEight/code_test.go

@@ -0,0 +1,18 @@
+package dayeight
+
+import "testing"
+
+var testInput = []string{
+	`""`,
+	`"abc"`,
+	`"aaa\"aaa"`,
+	`"\x27"`,
+}
+
+func TestPartOne(t *testing.T) {
+	expected := 12
+	got := PartOne(testInput)
+	if got != expected {
+		t.Errorf("PartOne() = %d, want %d", got, expected)
+	}
+}