Add dbx library: PostgreSQL cluster with master/replica routing, retry, health checking

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config_test.go

@@ -0,0 +1,72 @@
+package dbx
+
+import (
+	"testing"
+	"time"
+)
+
+func TestConfigDefaults(t *testing.T) {
+	cfg := Config{}
+	cfg.defaults()
+
+	if cfg.Logger == nil {
+		t.Error("Logger should not be nil after defaults")
+	}
+	if cfg.Retry.MaxAttempts != 3 {
+		t.Errorf("MaxAttempts = %d, want 3", cfg.Retry.MaxAttempts)
+	}
+	if cfg.Retry.BaseDelay != 50*time.Millisecond {
+		t.Errorf("BaseDelay = %v, want 50ms", cfg.Retry.BaseDelay)
+	}
+	if cfg.Retry.MaxDelay != time.Second {
+		t.Errorf("MaxDelay = %v, want 1s", cfg.Retry.MaxDelay)
+	}
+	if cfg.HealthCheck.Interval != 5*time.Second {
+		t.Errorf("HealthCheck.Interval = %v, want 5s", cfg.HealthCheck.Interval)
+	}
+	if cfg.HealthCheck.Timeout != 2*time.Second {
+		t.Errorf("HealthCheck.Timeout = %v, want 2s", cfg.HealthCheck.Timeout)
+	}
+	if cfg.Master.Name != "master" {
+		t.Errorf("Master.Name = %q, want %q", cfg.Master.Name, "master")
+	}
+}
+
+func TestConfigDefaultsReplicaNames(t *testing.T) {
+	cfg := Config{
+		Replicas: []NodeConfig{
+			{DSN: "a"},
+			{Name: "custom", DSN: "b"},
+			{DSN: "c"},
+		},
+	}
+	cfg.defaults()
+
+	if cfg.Replicas[0].Name != "replica-1" {
+		t.Errorf("Replica[0].Name = %q, want %q", cfg.Replicas[0].Name, "replica-1")
+	}
+	if cfg.Replicas[1].Name != "custom" {
+		t.Errorf("Replica[1].Name = %q, want %q", cfg.Replicas[1].Name, "custom")
+	}
+	if cfg.Replicas[2].Name != "replica-3" {
+		t.Errorf("Replica[2].Name = %q, want %q", cfg.Replicas[2].Name, "replica-3")
+	}
+}
+
+func TestConfigDefaultsNoOverwrite(t *testing.T) {
+	cfg := Config{
+		Retry: RetryConfig{
+			MaxAttempts: 5,
+			BaseDelay:   100 * time.Millisecond,
+			MaxDelay:    2 * time.Second,
+		},
+	}
+	cfg.defaults()
+
+	if cfg.Retry.MaxAttempts != 5 {
+		t.Errorf("MaxAttempts = %d, want 5", cfg.Retry.MaxAttempts)
+	}
+	if cfg.Retry.BaseDelay != 100*time.Millisecond {
+		t.Errorf("BaseDelay = %v, want 100ms", cfg.Retry.BaseDelay)
+	}
+}