feat(server-go): 耗材管理（库存/预警/采购建议，#16）

server-go/internal/model/consumable_test.go

@@ -0,0 +1,44 @@
+package model
+
+import (
+	"testing"
+	"time"
+)
+
+func TestConsumableLowStockAlert(t *testing.T) {
+	c := Consumable{Quantity: 5, MinQuantity: 10}
+	if !c.LowStockAlert() {
+		t.Error("库存低于安全阈值应预警")
+	}
+	c2 := Consumable{Quantity: 10, MinQuantity: 10}
+	if c2.LowStockAlert() {
+		t.Error("库存等于安全阈值不应预警")
+	}
+}
+
+func TestConsumableExpiringAlert(t *testing.T) {
+	soon := time.Now().Add(10 * 24 * time.Hour)
+	if !(Consumable{ExpiryDate: &soon}).ExpiringAlert(30) {
+		t.Error("30 天内到期应预警")
+	}
+	past := time.Now().Add(-24 * time.Hour)
+	if !(Consumable{ExpiryDate: &past}).ExpiringAlert(30) {
+		t.Error("已过期应预警")
+	}
+	far := time.Now().Add(60 * 24 * time.Hour)
+	if (Consumable{ExpiryDate: &far}).ExpiringAlert(30) {
+		t.Error("60 天后到期不应预警（30 天窗口）")
+	}
+	if (Consumable{}).ExpiringAlert(30) {
+		t.Error("无效期不应预警")
+	}
+}
+
+func TestPurchaseSuggestion(t *testing.T) {
+	if s := (Consumable{Quantity: 3, MinQuantity: 10}).PurchaseSuggestion(); s != 7 {
+		t.Errorf("建议采购量 = %v, want 7", s)
+	}
+	if s := (Consumable{Quantity: 10, MinQuantity: 10}).PurchaseSuggestion(); s != 0 {
+		t.Errorf("不缺货建议采购量 = %v, want 0", s)
+	}
+}