Add tests

tests/DCC/GP_DCC_Temperature_Simplified_variant/AdministrativeData.Items_variant.test.ts

+/**
+ * @jest-environment ./tests/XMLEnvironment.ts
+ * @xml ./tests/resources/GP_Temperature_Simplified_variant.xml
+ */
+
+import { select } from "../../util";
+import { ItemType, DCCDocument, EquipmentClassType } from "../../../src";
+
+const base = "/dcc:digitalCalibrationCertificate/dcc:administrativeData/dcc:items";
+const xpath = {
+  items: {
+    item: {
+      equipmentClass: {
+        reference: `string(${base}/dcc:item[1]/dcc:equipmentClass[1]/dcc:reference)`,
+        classID: `string(${base}/dcc:item[1]/dcc:equipmentClass[1]/dcc:classID)`,
+      },
+    },
+  },
+};
+
+describe("GP_DCC_Temperature_Typical: ItemType", () => {
+  let dcc: DCCDocument, item: ItemType, equipmentClass: EquipmentClassType, dom;
+
+  beforeEach(async () => {
+    ({ dcc, dom } = await xmlEnv.recreateEnv());
+    item = dcc.digitalCalibrationCertificate.administrativeData.items.item[0];
+    equipmentClass = item.equipmentClass[0];
+  });
+
+  test("should get correct equipmentClass reference from XML", () => {
+    expect(equipmentClass.reference._text).toBe(select(xpath.items.item.equipmentClass.reference, dom));
+  });
+
+  test("should get correct equipmentClass classID from XML", () => {
+    expect(equipmentClass.classID._text).toBe(select(xpath.items.item.equipmentClass.classID, dom));
+  });
+});