cleanup, add empty profile writer test

src/ImageSharp/Metadata/Profiles/Exif/ExifWriter.cs

@@ -50,11 +50,6 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif
             IExifValue exifOffset = GetOffsetValue(this.ifdValues, this.exifValues, ExifTag.SubIFDOffset);
             IExifValue gpsOffset = GetOffsetValue(this.ifdValues, this.gpsValues, ExifTag.GPSIFDOffset);
 
-            if (this.ifdValues.Count == 0 && this.exifValues.Count == 0 && this.gpsValues.Count == 0)
-            {
-                return Array.Empty<byte>();
-            }
-
             uint ifdLength = this.GetLength(this.ifdValues);
             uint exifLength = this.GetLength(this.exifValues);
             uint gpsLength = this.GetLength(this.gpsValues);

tests/ImageSharp.Tests/Metadata/Profiles/Exif/ExifProfileTests.cs

@@ -87,6 +87,17 @@ namespace SixLabors.ImageSharp.Tests.Metadata.Profiles.Exif
             new ExifProfile(Array.Empty<byte>());
         }
 
+        [Fact]
+        public void EmptyWriter()
+        {
+            var profile = new ExifProfile() { Parts = ExifParts.GpsTags };
+            profile.SetValue(ExifTag.Copyright, "Copyright text");
+
+            byte[] bytes = profile.ToByteArray();
+            Assert.NotNull(bytes);
+            Assert.Empty(bytes);
+        }
+
         [Fact]
         public void ConstructorCopy()
         {
@@ -498,7 +509,6 @@ namespace SixLabors.ImageSharp.Tests.Metadata.Profiles.Exif
 
             // Assert
             int ifdOffset = ExifConstants.LittleEndianByteOrderMarker.Length;
-
             Assert.Equal(8U, BinaryPrimitives.ReadUInt32LittleEndian(actualBytes.Slice(ifdOffset, 4)));
 
             int nextIfdPointerOffset = ExifConstants.LittleEndianByteOrderMarker.Length + 4 + 2 + 12;