add two more unit tests

test/backend/assets/sidecar/metadata.jpg.json

@@ -0,0 +1,12 @@
+{
+  "size": {
+    "width": 10,
+    "height": 5
+  },
+  "creationDate": 1709057753000,
+  "fileSize": 4489,
+  "keywords": [
+    "floor",
+    "book"
+  ]
+}

test/backend/assets/sidecar/metadata_v2.jpg.json

@@ -0,0 +1,15 @@
+{
+  "size": {
+    "width": 10,
+    "height": 5
+  },
+  "creationDate": 1709057753000,
+  "fileSize": 4489,
+  "keywords": [
+    "floor",
+    "book",
+    "first",
+    "second"
+  ],
+  "rating": 0
+}

test/backend/assets/sidecar/metadata_v2.xmp

@@ -0,0 +1,18 @@
+<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="XMP Core 6.0.0">
+   <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
+      <rdf:Description rdf:about=""
+            xmlns:xmp="http://ns.adobe.com/xap/1.0/"
+            xmlns:MicrosoftPhoto="http://ns.microsoft.com/photo/1.0/"
+            xmlns:dc="http://purl.org/dc/elements/1.1/"
+            xmlns:lr="http://ns.adobe.com/lightroom/1.0/">
+         <xmp:Rating>0</xmp:Rating>
+         <MicrosoftPhoto:Rating>0</MicrosoftPhoto:Rating>
+         <dc:subject>
+            <rdf:Bag>
+               <rdf:li>first</rdf:li>
+               <rdf:li>second</rdf:li>
+            </rdf:Bag>
+         </dc:subject>
+      </rdf:Description>
+   </rdf:RDF>
+</x:xmpmeta>

test/backend/unit/model/threading/MetaDataLoader.spec.ts

@@ -117,6 +117,17 @@ describe('MetadataLoader', () => {
     expect(Utils.clone(data)).to.be.deep.equal(expected);
   });
 
+  it('should read keywords from photo without sidecar file', async () => {
+    const data = await MetadataLoader.loadPhotoMetadata(path.join(__dirname, '/../../../assets/sidecar/metadata.jpg'));
+    const expected = require(path.join(__dirname, '/../../../assets/sidecar/metadata.jpg.json'));
+    expect(Utils.clone(data)).to.be.deep.equal(expected);
+  });
+
+  it('should merge keywords from photo with keywords from sidecar', async () => {
+    const data = await MetadataLoader.loadPhotoMetadata(path.join(__dirname, '/../../../assets/sidecar/metadata_v2.jpg'));
+    const expected = require(path.join(__dirname, '/../../../assets/sidecar/metadata_v2.jpg.json')); //"metadata_v2.jpg" is identical to "metadata.jpg" and "metadata_v2.xmp" contains 2 different keywords    expect(Utils.clone(data)).to.be.deep.equal(expected);
+  });
+
 
   describe('should load jpg with proper height and orientation', () => {
     it('jpg 1', async () => {