test: logging test

Signed-off-by: Carlos A Becker <caarlos0@gmail.com>

logging_test.go

@@ -0,0 +1,29 @@
+package tea
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLogToFile(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "log.txt")
+	prefix := "logprefix"
+	f, err := LogToFile(path, prefix)
+	if err != nil {
+		t.Error(err)
+	}
+	log.SetFlags(log.Lmsgprefix)
+	log.Println("some test log")
+	if err := f.Close(); err != nil {
+		t.Error(err)
+	}
+	out, err := os.ReadFile(path)
+	if err != nil {
+		t.Error(err)
+	}
+	if string(out) != prefix+" some test log\n" {
+		t.Fatalf("wrong log msg: %q", string(out))
+	}
+}