fix: parse -o flag correctly to resolve output filename

Fix bug where -o flag value was read as pointer instead of string value,
causing memory addresses to be printed and output path to resolve to ".xlsx".

main_test.go

@@ -0,0 +1,106 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/xuri/excelize/v2"
+)
+
+func writeTempCSV(t *testing.T, dir, name, content string) string {
+	t.Helper()
+	path := filepath.Join(dir, name)
+	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+	return path
+}
+
+func TestRun_OutputPath(t *testing.T) {
+	dir := t.TempDir()
+	csv := writeTempCSV(t, dir, "data.csv", "name,age\nAlice,30\nBob,25\n")
+	out := filepath.Join(dir, "result.xlsx")
+
+	if err := run([]string{csv}, out, "auto", "utf8"); err != nil {
+		t.Fatalf("run() error: %v", err)
+	}
+
+	if _, err := os.Stat(out); os.IsNotExist(err) {
+		t.Fatalf("output file not created: %s", out)
+	}
+}
+
+func TestRun_SheetContent(t *testing.T) {
+	dir := t.TempDir()
+	csv := writeTempCSV(t, dir, "sheet1.csv", "col1;col2\nfoo;bar\n")
+	out := filepath.Join(dir, "out.xlsx")
+
+	if err := run([]string{csv}, out, ";", "utf8"); err != nil {
+		t.Fatalf("run() error: %v", err)
+	}
+
+	f, err := excelize.OpenFile(out)
+	if err != nil {
+		t.Fatalf("OpenFile: %v", err)
+	}
+
+	val, err := f.GetCellValue("sheet1", "A1")
+	if err != nil {
+		t.Fatalf("GetCellValue: %v", err)
+	}
+	if val != "col1" {
+		t.Errorf("A1 = %q, want %q", val, "col1")
+	}
+
+	val, err = f.GetCellValue("sheet1", "B2")
+	if err != nil {
+		t.Fatalf("GetCellValue: %v", err)
+	}
+	if val != "bar" {
+		t.Errorf("B2 = %q, want %q", val, "bar")
+	}
+}
+
+func TestRun_MultipleSheets(t *testing.T) {
+	dir := t.TempDir()
+	csv1 := writeTempCSV(t, dir, "alpha.csv", "x\n1\n")
+	csv2 := writeTempCSV(t, dir, "beta.csv", "y\n2\n")
+	out := filepath.Join(dir, "multi.xlsx")
+
+	if err := run([]string{csv1, csv2}, out, "auto", "utf8"); err != nil {
+		t.Fatalf("run() error: %v", err)
+	}
+
+	f, err := excelize.OpenFile(out)
+	if err != nil {
+		t.Fatalf("OpenFile: %v", err)
+	}
+
+	sheets := f.GetSheetList()
+	if len(sheets) != 2 {
+		t.Fatalf("got %d sheets, want 2", len(sheets))
+	}
+	if sheets[0] != "alpha" || sheets[1] != "beta" {
+		t.Errorf("sheets = %v, want [alpha beta]", sheets)
+	}
+}
+
+func TestRun_CustomOutputFilename(t *testing.T) {
+	dir := t.TempDir()
+	csv := writeTempCSV(t, dir, "input.csv", "a,b\n1,2\n")
+	out := filepath.Join(dir, "custom_name.xlsx")
+
+	if err := run([]string{csv}, out, ",", "utf8"); err != nil {
+		t.Fatalf("run() error: %v", err)
+	}
+
+	if _, err := os.Stat(out); os.IsNotExist(err) {
+		t.Fatalf("expected output at %s, not found", out)
+	}
+	// ensure default name was NOT created
+	defaultOut := filepath.Join(dir, "output.xlsx")
+	if _, err := os.Stat(defaultOut); !os.IsNotExist(err) {
+		t.Errorf("unexpected file created at %s", defaultOut)
+	}
+}