Avoid allocating empty arrays

CA1825: Avoid zero-length array allocations
https://docs.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1825

src/TaglibSharp.Tests/Images/AddImageMetadataTests.cs

@@ -108,7 +108,7 @@ public static void AddXMPTest2 (string sample_file, string tmp_file, bool contai
 			xmp_tag.Comment = null;
 			xmp_tag.Software = test_comment;
 
-			Assert.AreEqual (new string[] { }, xmp_tag.Keywords);
+			Assert.AreEqual (Array.Empty<string> (), xmp_tag.Keywords);
 			Assert.AreEqual (null, xmp_tag.Comment);
 			Assert.AreEqual (test_comment, xmp_tag.Software);
 
@@ -119,7 +119,7 @@ public static void AddXMPTest2 (string sample_file, string tmp_file, bool contai
 			xmp_tag = file.GetTag (TagTypes.XMP, false) as XmpTag;
 			Assert.IsNotNull (xmp_tag, "XMP Tag not read");
 
-			Assert.AreEqual (new string[] { }, xmp_tag.Keywords);
+			Assert.AreEqual (Array.Empty<string> (), xmp_tag.Keywords);
 			Assert.AreEqual (null, xmp_tag.Comment);
 			Assert.AreEqual (test_comment, xmp_tag.Software);
 		}

src/TaglibSharp.Tests/Images/CopyFromTest.cs

@@ -21,8 +21,8 @@ public void TestJPGtoTIFF ()
 			Assert.AreEqual (TagTypes.TiffIFD | TagTypes.XMP, file2.TagTypes);
 			Assert.AreEqual ("%test comment%", file1.ImageTag.Comment);
 			Assert.AreEqual (string.Empty, file2.ImageTag.Comment);
-			Assert.AreEqual (new string[] { }, file1.ImageTag.Keywords);
-			Assert.AreEqual (new string[] { }, file2.ImageTag.Keywords);
+			Assert.AreEqual (Array.Empty<string> (), file1.ImageTag.Keywords);
+			Assert.AreEqual (Array.Empty<string> (), file2.ImageTag.Keywords);
 			Assert.AreEqual (null, file1.ImageTag.Rating);
 			Assert.AreEqual (0, file2.ImageTag.Rating);
 			Assert.AreEqual (new DateTime (2009, 8, 9, 19, 12, 44), (DateTime)file1.ImageTag.DateTime);
@@ -62,8 +62,8 @@ public void TestJPGtoTIFF ()
 			Assert.AreEqual (TagTypes.TiffIFD | TagTypes.XMP, file2.TagTypes);
 			Assert.AreEqual ("%test comment%", file1.ImageTag.Comment);
 			Assert.AreEqual ("%test comment%", file2.ImageTag.Comment);
-			Assert.AreEqual (new string[] { }, file1.ImageTag.Keywords);
-			Assert.AreEqual (new string[] { }, file2.ImageTag.Keywords);
+			Assert.AreEqual (Array.Empty<string> (), file1.ImageTag.Keywords);
+			Assert.AreEqual (Array.Empty<string> (), file2.ImageTag.Keywords);
 			Assert.AreEqual (null, file1.ImageTag.Rating);
 			Assert.AreEqual (null, file2.ImageTag.Rating);
 			Assert.AreEqual (new DateTime (2009, 8, 9, 19, 12, 44), (DateTime)file1.ImageTag.DateTime);

src/TaglibSharp.Tests/Images/GifExiftoolLongCommentTest.cs

@@ -20,7 +20,7 @@ public void Test ()
 				true,
 				new GifExiftoolLongCommentTestInvariantValidator (),
 				NoModificationValidator.Instance,
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true),
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true),
 				new CommentModificationValidator (long_comment_orig),
 				new CommentModificationValidator (long_comment_orig, long_comment_test),
 				new TagCommentModificationValidator (long_comment_orig, TagTypes.GifComment, true),

src/TaglibSharp.Tests/Images/GifExiftoolTangled3Test.cs

@@ -19,7 +19,7 @@ public void Test ()
 				true,
 				new GifExiftoolTangled3TestInvariantValidator (),
 				NoModificationValidator.Instance,
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, false),
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, false),
 				new CommentModificationValidator ("Created with GIMP"),
 				new TagCommentModificationValidator ("Created with GIMP", TagTypes.GifComment, true),
 				new RemoveMetadataValidator (TagTypes.GifComment)

src/TaglibSharp.Tests/Images/ImageTagTests.cs

@@ -20,7 +20,7 @@ public void TestXMPImageTag ()
 			Assert.IsNotNull (tag);
 
 			Assert.AreEqual (null, tag.Comment, "Comment");
-			Assert.AreEqual (new string[] { }, tag.Keywords, "Keywords");
+			Assert.AreEqual (Array.Empty<string> (), tag.Keywords, "Keywords");
 			Assert.AreEqual (0, tag.Rating, "Rating");
 			Assert.AreEqual (null, tag.DateTime, "DateTime");
 			Assert.AreEqual (ImageOrientation.None, tag.Orientation, "Orientation");

src/TaglibSharp.Tests/Images/JpegNikon1Bibble5Test.cs

@@ -20,7 +20,7 @@ public void Test ()
 				new CommentModificationValidator (string.Empty),
 				new TagCommentModificationValidator (null, TagTypes.TiffIFD, true),
 				new TagCommentModificationValidator (null, TagTypes.XMP, true),
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true)
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true)
 			);
 		}
 	}

src/TaglibSharp.Tests/Images/JpegNikon2Bibble5Test.cs

@@ -20,7 +20,7 @@ public void Test ()
 				new CommentModificationValidator (string.Empty),
 				new TagCommentModificationValidator (null, TagTypes.TiffIFD, true),
 				new TagCommentModificationValidator (null, TagTypes.XMP, true),
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true)
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true)
 			);
 		}
 	}

src/TaglibSharp.Tests/Images/JpegOlympus2Test.cs

@@ -165,7 +165,7 @@ public void CheckXMP (File file)
 
 			Assert.IsNotNull (tag, "tag");
 
-			Assert.AreEqual (new string[] { }, tag.Keywords);
+			Assert.AreEqual (Array.Empty<string> (), tag.Keywords);
 			Assert.AreEqual ("OLYMPUS CORPORATION", tag.Make);
 			Assert.AreEqual ("C5060WZ", tag.Model);
 			Assert.AreEqual ("Adobe Photoshop Elements 4.0", tag.Software);

src/TaglibSharp.Tests/Images/PefPentaxKd10Test.cs

@@ -30,7 +30,7 @@ public void ValidateMetadataInvariants (TagLib.Image.File file)
 			var imagetag = file.ImageTag;
 			Assert.IsNotNull (imagetag);
 			Assert.AreEqual (String.Empty, imagetag.Comment, "Comment");
-			Assert.AreEqual (new string[] { }, imagetag.Keywords, "Keywords");
+			Assert.AreEqual (Array.Empty<string> (), imagetag.Keywords, "Keywords");
 			Assert.AreEqual (null, imagetag.Rating, "Rating");
 			Assert.AreEqual (TagLib.Image.ImageOrientation.LeftBottom, imagetag.Orientation, "Orientation");
 			Assert.AreEqual ("K10D Ver 1.31          ", imagetag.Software, "Software");

src/TaglibSharp.Tests/Images/RawLeicaDigilux2Test.cs

@@ -26,7 +26,7 @@ public void ValidateMetadataInvariants (TagLib.Image.File file)
 			var imagetag = file.ImageTag;
 			Assert.IsNotNull (imagetag);
 			Assert.AreEqual (String.Empty, imagetag.Comment, "Comment");
-			Assert.AreEqual (new string[] { }, imagetag.Keywords, "Keywords");
+			Assert.AreEqual (Array.Empty<string> (), imagetag.Keywords, "Keywords");
 			Assert.AreEqual (null, imagetag.Rating, "Rating");
 			Assert.AreEqual (TagLib.Image.ImageOrientation.TopLeft, imagetag.Orientation, "Orientation");
 			Assert.AreEqual (null, imagetag.Software, "Software");

src/TaglibSharp.Tests/Images/RecursiveIFDTest.cs

@@ -1,3 +1,5 @@
+using System;
+
 using NUnit.Framework;
 using TagLib;
 using TagLib.IFD;
@@ -259,7 +261,7 @@ public void ValidateMetadataInvariants (TagLib.Image.File file)
 				Assert.IsNotNull (entry, "Entry 0x92D6 missing in IFD 0");
 				Assert.IsNotNull (entry as UndefinedIFDEntry, "Entry is not an undefined IFD entry!");
 				var parsed_bytes = (entry as UndefinedIFDEntry).Data.Data;
-				var bytes = new byte[] { };
+				var bytes = Array.Empty<byte> ();
 				Assert.AreEqual (bytes, parsed_bytes);
 			}
 			// Thumbnail.0x0103 (Compression/Short/1) "6"

src/TaglibSharp.Tests/Images/Rw2PanasonicG1Test.cs

@@ -33,7 +33,7 @@ public void ValidateMetadataInvariants (TagLib.Image.File file)
 			var imagetag = file.ImageTag;
 			Assert.IsNotNull (imagetag);
 			Assert.AreEqual (String.Empty, imagetag.Comment, "Comment");
-			Assert.AreEqual (new string[] { }, imagetag.Keywords, "Keywords");
+			Assert.AreEqual (Array.Empty<string> (), imagetag.Keywords, "Keywords");
 			Assert.AreEqual (null, imagetag.Rating, "Rating");
 			Assert.AreEqual (TagLib.Image.ImageOrientation.TopLeft, imagetag.Orientation, "Orientation");
 			Assert.AreEqual (null, imagetag.Software, "Software");

src/TaglibSharp.Tests/Images/TiffCanonBibble516BitTest.cs

@@ -20,7 +20,7 @@ public void Test ()
 				new CommentModificationValidator (string.Empty),
 				new TagCommentModificationValidator (null, TagTypes.TiffIFD, true),
 				new TagCommentModificationValidator (null, TagTypes.XMP, true),
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true)
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true)
 			);
 		}
 	}

src/TaglibSharp.Tests/Images/TiffCanonBibble58BitTest.cs

@@ -20,7 +20,7 @@ public void Test ()
 				new CommentModificationValidator (string.Empty),
 				new TagCommentModificationValidator (null, TagTypes.TiffIFD, true),
 				new TagCommentModificationValidator (null, TagTypes.XMP, true),
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true)
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true)
 			);
 		}
 	}

src/TaglibSharp.Tests/Images/TiffNikon1Bibble516BitTest.cs

@@ -20,7 +20,7 @@ public void Test ()
 				new CommentModificationValidator (string.Empty),
 				new TagCommentModificationValidator (null, TagTypes.TiffIFD, true),
 				new TagCommentModificationValidator (null, TagTypes.XMP, true),
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true)
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true)
 			);
 		}
 	}

src/TaglibSharp.Tests/Images/TiffNikon1Bibble58BitTest.cs

@@ -20,7 +20,7 @@ public void Test ()
 				new CommentModificationValidator (string.Empty),
 				new TagCommentModificationValidator (null, TagTypes.TiffIFD, true),
 				new TagCommentModificationValidator (null, TagTypes.XMP, true),
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true)
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true)
 			);
 		}
 	}

src/TaglibSharp.Tests/Images/TiffNikon2Bibble516BitTest.cs

@@ -20,7 +20,7 @@ public void Test ()
 				new CommentModificationValidator (string.Empty),
 				new TagCommentModificationValidator (null, TagTypes.TiffIFD, true),
 				new TagCommentModificationValidator (null, TagTypes.XMP, true),
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true)
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true)
 			);
 		}
 	}

src/TaglibSharp.Tests/Images/TiffNikon2Bibble58BitTest.cs

@@ -20,7 +20,7 @@ public void Test ()
 				new CommentModificationValidator (string.Empty),
 				new TagCommentModificationValidator (null, TagTypes.TiffIFD, true),
 				new TagCommentModificationValidator (null, TagTypes.XMP, true),
-				new TagKeywordsModificationValidator (new string[] { }, TagTypes.XMP, true)
+				new TagKeywordsModificationValidator (Array.Empty<string> (), TagTypes.XMP, true)
 			);
 		}
 	}

src/TaglibSharp.Tests/Images/Validators/KeywordsModificationValidator.cs

@@ -12,7 +12,7 @@ public class KeywordsModificationValidator : IMetadataModificationValidator
 		readonly string[] orig_keywords;
 		readonly string[] test_keywords = { "keyword 1", "§$&§%", "99 dsf", "ഈ ヰᛥกツ" };
 
-		public KeywordsModificationValidator () : this (new string[] { }) { }
+		public KeywordsModificationValidator () : this (Array.Empty<string> ()) { }
 
 		public KeywordsModificationValidator (string[] orig_keywords)
 		{

src/TaglibSharp.Tests/Images/Validators/TagKeywordsModificationValidator.cs

@@ -12,7 +12,7 @@ public class TagKeywordsModificationValidator : KeywordsModificationValidator
 		readonly bool tag_present;
 		readonly TagTypes type;
 
-		public TagKeywordsModificationValidator (TagTypes type, bool tag_present) : this (new string[] { }, type, tag_present) { }
+		public TagKeywordsModificationValidator (TagTypes type, bool tag_present) : this (Array.Empty<string> (), type, tag_present) { }
 
 		public TagKeywordsModificationValidator (string[] orig_keywords, TagTypes type, bool tag_present) : base (orig_keywords)
 		{

src/TaglibSharp.Tests/TaggingFormats/ApeTest.cs

@@ -1,3 +1,5 @@
+using System;
+
 using NUnit.Framework;
 using TagLib;
 using Tag = TagLib.Ape.Tag;
@@ -61,7 +63,7 @@ public void TestPerformers ()
 				}
 			});
 
-			tag.Performers = new string[0];
+			tag.Performers = Array.Empty<string> ();
 
 			TagTestWithSave (ref tag, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -89,7 +91,7 @@ public void TestAlbumArtists ()
 				}
 			});
 
-			tag.AlbumArtists = new string[0];
+			tag.AlbumArtists = Array.Empty<string> ();
 
 			TagTestWithSave (ref tag, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -117,7 +119,7 @@ public void TestComposers ()
 				}
 			});
 
-			tag.Composers = new string[0];
+			tag.Composers = Array.Empty<string> ();
 
 			TagTestWithSave (ref tag, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -205,7 +207,7 @@ public void TestGenres ()
 				}
 			});
 
-			tag.Genres = new string[0];
+			tag.Genres = Array.Empty<string> ();
 
 			TagTestWithSave (ref tag, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -501,7 +503,7 @@ public void TestPictures ()
 				}
 			});
 
-			tag.Pictures = new Picture[0];
+			tag.Pictures = Array.Empty<Picture> ();
 
 			TagTestWithSave (ref tag, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);

src/TaglibSharp.Tests/TaggingFormats/AsfTest.cs

@@ -1,3 +1,5 @@
+using System;
+
 using NUnit.Framework;
 using TagLib;
 using File = TagLib.Asf.File;
@@ -60,7 +62,7 @@ public void TestPerformers ()
 				}
 			});
 
-			file.Tag.Performers = new string[0];
+			file.Tag.Performers = Array.Empty<string> ();
 
 			TagTestWithSave (ref file, abst, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -88,7 +90,7 @@ public void TestAlbumArtists ()
 				}
 			});
 
-			file.Tag.AlbumArtists = new string[0];
+			file.Tag.AlbumArtists = Array.Empty<string> ();
 
 			TagTestWithSave (ref file, abst, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -116,7 +118,7 @@ public void TestComposers ()
 				}
 			});
 
-			file.Tag.Composers = new string[0];
+			file.Tag.Composers = Array.Empty<string> ();
 
 			TagTestWithSave (ref file, abst, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -204,7 +206,7 @@ public void TestGenres ()
 				}
 			});
 
-			file.Tag.Genres = new string[0];
+			file.Tag.Genres = Array.Empty<string> ();
 
 			TagTestWithSave (ref file, abst, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -500,7 +502,7 @@ public void TestPictures ()
 				}
 			});
 
-			file.Tag.Pictures = new Picture[0];
+			file.Tag.Pictures = Array.Empty<Picture> ();
 
 			TagTestWithSave (ref file, abst, delegate (Tag t, string m) {
 				Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);

src/TaglibSharp.Tests/TaggingFormats/DivXTest.cs

@@ -59,7 +59,7 @@ public void TestPerformers ()
 			Assert.IsFalse (tag.IsEmpty, "Still not empty");
 			Assert.AreEqual ("A123456789; B123456789; C12345", tag.JoinedPerformers);
 
-			tag.Performers = new string[0];
+			tag.Performers = Array.Empty<string> ();
 			Assert.IsTrue (tag.IsEmpty, "Again empty");
 			Assert.AreEqual (0, tag.Performers.Length, "Again empty");
 
@@ -164,7 +164,7 @@ public void TestGenres ()
 			Assert.IsTrue (tag.IsEmpty, "Still empty");
 			Assert.AreEqual (0, tag.Genres.Length, "Still empty");
 
-			tag.Genres = new string[0];
+			tag.Genres = Array.Empty<string> ();
 			Assert.IsTrue (tag.IsEmpty, "Again empty");
 			Assert.AreEqual (0, tag.Genres.Length, "Again empty");
 

src/TaglibSharp.Tests/TaggingFormats/Id3V1Test.cs

@@ -59,7 +59,7 @@ public void TestPerformers ()
 			Assert.IsFalse (tag.IsEmpty, "Still not empty");
 			Assert.AreEqual ("A123456789; B123456789; C1234567", tag.JoinedPerformers);
 
-			tag.Performers = new string[0];
+			tag.Performers = Array.Empty<string> ();
 			Assert.IsTrue (tag.IsEmpty, "Again empty");
 			Assert.AreEqual (0, tag.Performers.Length, "Again empty");
 
@@ -228,7 +228,7 @@ public void TestGenres ()
 			Assert.IsTrue (tag.IsEmpty, "Still empty");
 			Assert.AreEqual (0, tag.Genres.Length, "Still empty");
 
-			tag.Genres = new string[0];
+			tag.Genres = Array.Empty<string> ();
 			Assert.IsTrue (tag.IsEmpty, "Again empty");
 			Assert.AreEqual (0, tag.Genres.Length, "Again empty");
 

src/TaglibSharp.Tests/TaggingFormats/Id3V2Test.cs

@@ -1,4 +1,6 @@
 using NUnit.Framework;
+
+using System;
 using System.Collections.Generic;
 using TagLib;
 using TagLib.Id3v2;
@@ -68,7 +70,7 @@ public void TestPerformers ()
 					}
 				});
 
-				tag.Performers = new string[0];
+				tag.Performers = Array.Empty<string> ();
 
 				TagTestWithSave (ref tag, delegate (Tag t, string m) {
 					Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -99,7 +101,7 @@ public void TestAlbumArtists ()
 					}
 				});
 
-				tag.AlbumArtists = new string[0];
+				tag.AlbumArtists = Array.Empty<string> ();
 
 				TagTestWithSave (ref tag, delegate (Tag t, string m) {
 					Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -130,7 +132,7 @@ public void TestComposers ()
 					}
 				});
 
-				tag.Composers = new string[0];
+				tag.Composers = Array.Empty<string> ();
 
 				TagTestWithSave (ref tag, delegate (Tag t, string m) {
 					Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -237,7 +239,7 @@ public void TestGenres ()
 					}
 				});
 
-				tag.Genres = new string[0];
+				tag.Genres = Array.Empty<string> ();
 
 				TagTestWithSave (ref tag, delegate (Tag t, string m) {
 					Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
@@ -567,7 +569,7 @@ public void TestPictures ()
 					}
 				});
 
-				tag.Pictures = new Picture[0];
+				tag.Pictures = Array.Empty<Picture> ();
 
 				TagTestWithSave (ref tag, delegate (Tag t, string m) {
 					Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);