Create method to get node by eid

While writing some unit tests using xpaths, I stumbled upon some
limitations of jsdom (the dom implementation used in the tests): It e.g.
does not support upper case characters within either the xpath, which is
something we need for e.g. the eIds (see also:
jsdom/jsdom#2530). Sadly the support for
xpaths is even worse with happy-dom :/

I therefore decided to mock the implementation of the method for
evaluating xpaths in the unit tests using the
 [xpath](https://www.npmjs.com/package/xpath) library.

RISDEV-3932

frontend/package.json

@@ -77,6 +77,7 @@
     "unplugin-icons": "~0.19.0",
     "vite": "~5.2.10",
     "vitest": "~1.6.0",
-    "vue-tsc": "~2.0.14"
+    "vue-tsc": "~2.0.14",
+    "xpath": "^0.0.34"
   }
 }

frontend/src/services/ldmldeService.spec.ts

@@ -0,0 +1,40 @@
+import { xmlStringToDocument } from "@/services/xmlService"
+import { describe, expect, it, vi } from "vitest"
+import { getNodeByEid } from "@/services/ldmldeService"
+import { useNamespaces } from "xpath"
+
+// The DOM implementation used by our unit tests (jsdom) does not have a good enough xpath support for our tests.
+// Therefore, we need to use a different library to evaluate the xpath.
+vi.mock("@/services/xmlService", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/services/xmlService")>()),
+  evaluateXPath: (xpath: string, node: Node) =>
+    useNamespaces({
+      akn: "http://Inhaltsdaten.LegalDocML.de/1.6/",
+    })(xpath, node, true),
+}))
+
+describe("ldmldeService", () => {
+  describe("getNodeByEid", () => {
+    it("should parse xml string", () => {
+      const document =
+        xmlStringToDocument(`<?xml version="1.0" encoding="UTF-8"?>
+        <?xml-model href="../../../Grammatiken/legalDocML.de.sch" schematypens="http://purl.oclc.org/dsdl/schematron"?>
+        <akn:akomaNtoso xmlns:akn="http://Inhaltsdaten.LegalDocML.de/1.6/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://Metadaten.LegalDocML.de/1.6/ ../../../Grammatiken/legalDocML.de-metadaten.xsd                        http://Inhaltsdaten.LegalDocML.de/1.6/ ../../../Grammatiken/legalDocML.de-regelungstextverkuendungsfassung.xsd">
+          <akn:act name="regelungstext" eId="hauptteil-1">
+            <akn:body GUID="0B4A8E1F-65EF-4B7C-9E22-E83BA6B73CD8" eId="hauptteil-1">
+              <akn:article GUID="cdbfc728-a070-42d9-ba2f-357945afef06" eId="hauptteil-1_art-1" period="#geltungszeitgr-1" refersTo="hauptaenderung">
+                <akn:num GUID="25a9acae-7463-4490-bc3f-8258b629d7e9" eId="hauptteil-1_art-1_bezeichnung-1">
+                   <akn:marker GUID="81c9c481-9427-4f03-9f51-099aa9b2201e" eId="hauptteil-1_art-1_bezeichnung-1_zaehlbez-1" name="1"/>Artikel 1</akn:num>
+                <akn:heading GUID="92827aa8-8118-4207-9f93-589345f0bab6" eId="hauptteil-1_art-1_überschrift-1">Änderung des
+                   Bundesverfassungsschutzgesetzes</akn:heading>
+              </akn:article>
+            </akn:body>
+          </akn:act>
+        </akn:akomaNtoso>
+      `)
+
+      const node = getNodeByEid(document, "hauptteil-1_art-1_bezeichnung-1")
+      expect(node?.textContent?.trim()).to.eq("Artikel 1")
+    })
+  })
+})

frontend/src/services/ldmldeService.ts

@@ -0,0 +1,5 @@
+import { evaluateXPath } from "@/services/xmlService"
+
+export function getNodeByEid(xml: Document, eid: string) {
+  return evaluateXPath(`//*[@eId="${eid}"]`, xml)
+}