test: add unit test for PartOne

internal/2025/DaySeven/code_test.go

@@ -0,0 +1,30 @@
+package dayseven
+
+import "testing"
+
+var testInput = []string{
+	".......S.......",
+	"...............",
+	".......^.......",
+	"...............",
+	"......^.^......",
+	"...............",
+	".....^.^.^.....",
+	"...............",
+	"....^.^...^....",
+	"...............",
+	"...^.^...^.^...",
+	"...............",
+	"..^...^.....^..",
+	"...............",
+	".^.^.^.^.^...^.",
+	"...............",
+}
+
+func TestPartOne(t *testing.T) {
+	expected := 21
+	got := PartOne(testInput)
+	if got != expected {
+		t.Errorf("PartOne() = %d, want %d", got, expected)
+	}
+}