add test

tests/ImageSharp.Tests/Metadata/Profiles/Exif/Values/ExifValuesTests.cs

@@ -311,7 +311,6 @@ namespace SixLabors.ImageSharp.Tests.Metadata.Profiles.Exif.Values
             { ExifTag.ExifVersion },
             { ExifTag.ComponentsConfiguration },
             { ExifTag.MakerNote },
-            { ExifTag.UserComment },
             { ExifTag.FlashpixVersion },
             { ExifTag.SpatialFrequencyResponse },
             { ExifTag.SpatialFrequencyResponse2 },
@@ -319,6 +318,11 @@ namespace SixLabors.ImageSharp.Tests.Metadata.Profiles.Exif.Values
             { ExifTag.CFAPattern },
             { ExifTag.DeviceSettingDescription },
             { ExifTag.ImageSourceData },
+        };
+
+        public static TheoryData<ExifTag> EncodedStringTags => new TheoryData<ExifTag>
+        {
+            { ExifTag.UserComment },
             { ExifTag.GPSProcessingMethod },
             { ExifTag.GPSAreaInformation }
         };
@@ -593,5 +597,19 @@ namespace SixLabors.ImageSharp.Tests.Metadata.Profiles.Exif.Values
             var typed = (ExifByteArray)value;
             Assert.Equal(expected, typed.Value);
         }
+
+        [Theory]
+        [MemberData(nameof(EncodedStringTags))]
+        public void ExifEncodedStringTests(ExifTag tag)
+        {
+            var expected = new EncodedString("test string", EncodedStringCode.JIS);
+            ExifValue value = ExifValues.Create(tag);
+
+            Assert.False(value.TrySetValue(expected.ToString()));
+            Assert.True(value.TrySetValue(expected));
+
+            var typed = (ExifEncodedString)value;
+            Assert.Equal(expected, typed.Value);
+        }
     }
 }