Added a test for offset-fix and found another bug - also fixed

src/common/Utils.ts

@@ -144,11 +144,11 @@ export class Utils {
   //function to extract offset string from timestamp string, returns undefined if timestamp does not contain offset
   static timestampToOffsetString(timestamp: string) {
     try {
-      const idx = timestamp.indexOf("+");
-      if (idx > 0) {
-        return timestamp.substring(idx, timestamp.length);
-      }
-      if (timestamp.indexOf("Z") > 0) {
+      const offsetRegex = /[+-]\d{2}:\d{2}$/;
+      var match = timestamp.match(offsetRegex);
+      if (match) {
+        return match[0];
+      } else if (timestamp.indexOf("Z") > 0) {
         return '+00:00';
       }
       return undefined;

test/backend/assets/wild-2-small.json

@@ -0,0 +1,20 @@
+{
+    "size": {
+        "width": 306,
+        "height": 204
+    },
+    "creationDate": 1435943085000,
+    "fileSize": 62306,
+    "positionData": {
+        "country": "United States",
+        "state": "Arizona",
+        "city": "Williams"
+    },
+    "keywords": ["Akela the wolf", "Balu the bear", "Bearizona", "Hugin the raven", "USA", "USA Road trip"],
+    "cameraData": {
+        "make": "Canon",
+        "model": "Canon EOS 600D",
+        "lens": "EF-S15-85mm f/3.5-5.6 IS USM"
+    },
+    "creationDateOffset": "-07:00"
+}

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

@@ -179,6 +179,11 @@ describe('MetadataLoader', () => {
     const expected = require(path.join(__dirname, '/../../../assets/wild-1-small.json'));
     expect(Utils.clone(data)).to.be.deep.equal(expected);
   });
+  it('should load wild-2-small image with xmp-CreateDate from 2015 and negative offset', async () => {
+    const data = await MetadataLoader.loadPhotoMetadata(path.join(__dirname, '/../../../assets/wild-2-small.jpg'));
+    const expected = require(path.join(__dirname, '/../../../assets/wild-2-small.json'));
+    expect(Utils.clone(data)).to.be.deep.equal(expected);
+  });
 
   describe('should load jpg with edge case exif data', () => {
     const root = path.join(__dirname, '/../../../assets/edge_case_exif_data');