fix empty line scrubbing (#549)

Author: SimonCropp

docs/scrubbers.md

@@ -162,6 +162,20 @@ public class ScrubbersSample
                     ");
     }
 
+    [Fact]
+    public Task EmptyLine()
+    {
+        var settings = new VerifySettings();
+        settings.ScrubLinesWithReplace(
+            replaceLine: line =>
+            {
+                return "";
+            });
+        return Verify(
+            settings: settings,
+            target: @"");
+    }
+
     [Fact]
     public Task LinesFluent() =>
         Verify(
@@ -246,7 +260,7 @@ public class ScrubbersSample
             .ScrubEmptyLines();
 }
 ```
-<sup><a href='/src/Verify.Xunit.Tests/Scrubbers/ScrubbersSample.cs#L1-L121' title='Snippet source file'>snippet source</a> | <a href='#snippet-scrubberssamplexunit' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/Verify.Xunit.Tests/Scrubbers/ScrubbersSample.cs#L1-L135' title='Snippet source file'>snippet source</a> | <a href='#snippet-scrubberssamplexunit' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 

src/Directory.Build.props

@@ -2,7 +2,7 @@
 <Project>
   <PropertyGroup>
     <NoWarn>CS1591;CS0649;xUnit1026;xUnit1013;msb3277;CS0436</NoWarn>
-    <Version>17.1.4</Version>
+    <Version>17.1.5</Version>
     <ImplicitUsings>enable</ImplicitUsings>
     <LangVersion>10</LangVersion>
     <SuppressTfmSupportBuildWarnings>true</SuppressTfmSupportBuildWarnings>

src/Verify.Xunit.Tests/Scrubbers/ScrubbersSample.EmptyLine.verified.txt

@@ -0,0 +1 @@
+

src/Verify.Xunit.Tests/Scrubbers/ScrubbersSample.cs

@@ -34,6 +34,20 @@ public Task Lines()
                     ");
     }
 
+    [Fact]
+    public Task EmptyLine()
+    {
+        var settings = new VerifySettings();
+        settings.ScrubLinesWithReplace(
+            replaceLine: line =>
+            {
+                return "";
+            });
+        return Verify(
+            settings: settings,
+            target: @"");
+    }
+
     [Fact]
     public Task LinesFluent() =>
         Verify(

src/Verify/Serialization/Scrubbers/LinesScrubber.cs

@@ -21,7 +21,8 @@ public static void ReplaceLines(this StringBuilder input, Func<string, string?>
             }
         }
 
-        if (!theString.EndsWith("\n"))
+        if (theString.Length > 0 &&
+            !theString.EndsWith("\n"))
         {
             input.Length -= 1;
         }