diff --git a/internal/2025/DaySix/code_test.go b/internal/2025/DaySix/code_test.go
new file mode 100644
index 0000000..b30b739
--- /dev/null
+++ b/internal/2025/DaySix/code_test.go
@@ -0,0 +1,18 @@
+package daysix
+
+import "testing"
+
+var testInput = []string{
+	"123 328  51 64 ",
+	" 45 64  387 23 ",
+	"  6 98  215 314",
+	"*   +   *   +  ",
+}
+
+func TestPartOne(t *testing.T) {
+	expected := 4277556
+	got := PartOne(testInput)
+	if got != expected {
+		t.Errorf("PartOne() = %d, want %d", got, expected)
+	}
+}