Enable CA1820 and fix noncompliance

"Test for empty strings using string length"

.global.editorconfig.ini

@@ -76,6 +76,8 @@ dotnet_diagnostic.CA1310.severity = silent # SpecifyStringComparisonAnalyzer ver
 
 # Do not initialize unnecessarily
 dotnet_diagnostic.CA1805.severity = silent
+# Test for empty strings using string length
+dotnet_diagnostic.CA1820.severity = warning
 # Mark members as static
 dotnet_diagnostic.CA1822.severity = silent
 # Use property instead of Linq Enumerable method

src/BizHawk.Client.Common/movie/import/LsmvImport.cs

@@ -105,9 +105,9 @@ namespace BizHawk.Client.Common.movie.import
 						while (reader.ReadLine() is string line)
 						{
 							string author = line.Trim();
-							if (author != "")
+							if (author.Length is not 0)
 							{
-								if (authorLast != "")
+								if (authorLast.Length is not 0)
 								{
 									authorList += $"{authorLast}, ";
 								}
@@ -117,12 +117,12 @@ namespace BizHawk.Client.Common.movie.import
 						}
 					}
 
-					if (authorList != "")
+					if (authorList.Length is not 0)
 					{
 						authorList += "and ";
 					}
 
-					if (authorLast != "")
+					if (authorLast.Length is not 0)
 					{
 						authorList += authorLast;
 					}

src/BizHawk.Client.EmuHawk/config/FirmwareConfig.cs

@@ -631,7 +631,7 @@ namespace BizHawk.Client.EmuHawk
 			}
 			catch
 			{
-				if (errors != "")
+				if (errors.Length is not 0)
 				{
 					errors += "\n";
 				}

src/BizHawk.Client.EmuHawk/tools/Debugger/RegisterBoxControl.cs

@@ -159,7 +159,7 @@ namespace BizHawk.Client.EmuHawk
 						{
 							try
 							{
-								if (t.Text != "")
+								if (t.Text.Length is not 0)
 								{
 									Core.SetCpuRegister(t.Name, int.Parse(t.Text, System.Globalization.NumberStyles.HexNumber));
 								}		

src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.ListView.cs

@@ -1373,7 +1373,7 @@ namespace BizHawk.Client.EmuHawk
 			{
 				if (_axisTypedValue.Length is 0)
 				{
-					if (prevTyped != "")
+					if (prevTyped.Length is not 0)
 					{
 						value = ControllerType.Axes[_axisEditColumn].Neutral;
 						CurrentTasMovie.SetAxisState(_axisEditRow, _axisEditColumn, value);

src/BizHawk.Emulation.Common/DSKIdentifier.cs

@@ -217,7 +217,7 @@ namespace BizHawk.Emulation.Common
 			}
 
 			// last chance. use the possible value
-			if (IdentifiedSystem == VSystemID.Raw.AppleII && _possibleIdent != "")
+			if (IdentifiedSystem == VSystemID.Raw.AppleII && _possibleIdent.Length is not 0) // wait but it's not being used for the assignment?
 			{
 				IdentifiedSystem = VSystemID.Raw.ZXSpectrum;
 			}

src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs

@@ -134,7 +134,7 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 
 			foreach (var ROM in ROMs)
 			{
-				if (ROM != string.Empty)
+				if (ROM.Length is not 0)
 				{
 					var substrings = ROM.Split('~');
 					var name = substrings[0];
@@ -200,7 +200,7 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 
 			foreach (var View in Views)
 			{
-				if (View != string.Empty)
+				if (View.Length is not 0)
 				{
 					var substrings = View.Split('@');
 					setting.Options.Add(substrings[0], substrings[1]);

src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs

@@ -72,7 +72,7 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 				StartMAME(lp.Roms);
 			}
 
-			if (_loadFailure != string.Empty)
+			if (_loadFailure.Length is not 0)
 			{
 				Dispose();
 				throw new Exception("\n\n" + _loadFailure);