but

backend/internal/config/config_test.go

@@ -0,0 +1,28 @@
+package config
+
+import "testing"
+
+func TestTierForPriceID(t *testing.T) {
+	t.Parallel()
+
+	cfg := &Config{
+		StripePriceIDPremium: "price_premium_123",
+		StripePriceIDPro:     "price_pro_456",
+	}
+
+	tests := []struct {
+		priceID string
+		want    string
+	}{
+		{"price_premium_123", "premium"},
+		{"price_pro_456", "pro"},
+		{"price_unknown", ""},
+		{"", ""},
+	}
+
+	for _, tt := range tests {
+		if got := cfg.TierForPriceID(tt.priceID); got != tt.want {
+			t.Errorf("TierForPriceID(%q) = %q, want %q", tt.priceID, got, tt.want)
+		}
+	}
+}