First commit Go counter service

internal/config/logger_test.go

@@ -0,0 +1,73 @@
+package config
+
+import (
+	"log/slog"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestNewLogger_Invalid(t *testing.T) {
+	if _, _, err := NewLogger(LoggingConfig{Format: "xml"}); err == nil {
+		t.Error("expected error for format xml")
+	}
+	if _, _, err := NewLogger(LoggingConfig{Level: "loud"}); err == nil {
+		t.Error("expected error for level loud")
+	}
+}
+
+func TestNewLogger_Levels(t *testing.T) {
+	for _, tt := range []struct {
+		in   string
+		want slog.Level
+	}{{"", slog.LevelInfo}, {"debug", slog.LevelDebug}, {"INFO", slog.LevelInfo}, {"warn", slog.LevelWarn}, {"warning", slog.LevelWarn}, {"error", slog.LevelError}} {
+		got, err := parseLogLevel(tt.in)
+		if err != nil || got != tt.want {
+			t.Errorf("parseLogLevel(%q) = %v, %v; want %v", tt.in, got, err, tt.want)
+		}
+	}
+}
+
+// Rotation: after the file is renamed away, Reopen must create a fresh file at
+// the configured path and subsequent writes must land there.
+func TestLogWriter_Reopen(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "app.log")
+	w, err := newLogWriter(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer w.Close()
+	if _, err := w.Write([]byte("one\n")); err != nil {
+		t.Fatal(err)
+	}
+	rotated := filepath.Join(dir, "app.log.0")
+	if err := os.Rename(path, rotated); err != nil {
+		t.Fatal(err)
+	}
+	if err := w.Reopen(); err != nil {
+		t.Fatalf("Reopen: %v", err)
+	}
+	if _, err := w.Write([]byte("two\n")); err != nil {
+		t.Fatal(err)
+	}
+	old, _ := os.ReadFile(rotated)
+	fresh, _ := os.ReadFile(path)
+	if strings.TrimSpace(string(old)) != "one" || strings.TrimSpace(string(fresh)) != "two" {
+		t.Errorf("rotated=%q fresh=%q", old, fresh)
+	}
+}
+
+func TestLogWriter_StderrReopenIsNoop(t *testing.T) {
+	w, err := newLogWriter("stderr")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := w.Reopen(); err != nil {
+		t.Errorf("Reopen on stderr: %v", err)
+	}
+	if err := w.Close(); err != nil {
+		t.Errorf("Close on stderr: %v", err)
+	}
+}