.

Author: SimonCropp

src/Verify.Tests/LinesScrubberTests.cs

@@ -337,7 +337,7 @@ public void FilterLines_LineSpansMultipleChunks()
         builder.Append(longLine);
         builder.Append("\nkeep2");
 
-        builder.FilterLines(line => line == longLine);
+        builder.FilterLines(line => line.SequenceEqual(longLine));
 
         Assert.Equal("keep1\nkeep2", builder.ToString());
     }
@@ -352,7 +352,7 @@ public void FilterLines_NewlineAtChunkBoundary()
         builder.Append('\n');
         builder.Append("line2");
 
-        builder.FilterLines(line => line == chunkFiller);
+        builder.FilterLines(line => line.SequenceEqual(chunkFiller));
 
         Assert.Equal("line2", builder.ToString());
     }
@@ -367,7 +367,7 @@ public void FilterLines_CrLfSplitAcrossChunks()
         builder.Append("\r\n");
         builder.Append("nextline");
 
-        builder.FilterLines(line => line == lineContent);
+        builder.FilterLines(line => line.SequenceEqual(lineContent));
 
         Assert.Equal("nextline", builder.ToString());
     }
@@ -391,7 +391,7 @@ public void FilterLines_MultipleLinesSpanningChunks()
         }
 
         // Remove even-indexed lines
-        builder.FilterLines(line => lines.IndexOf(line) % 2 == 0);
+        builder.FilterLines(line => lines.IndexOf(line.ToString()) % 2 == 0);
 
         var expected = string.Join('\n', lines.Where((_, i) => i % 2 == 1));
         Assert.Equal(expected, builder.ToString());
@@ -406,7 +406,7 @@ public void FilterLines_VeryLongLineKept()
         builder.Append(longLine);
         builder.Append("\nremove");
 
-        builder.FilterLines(line => line == "remove");
+        builder.FilterLines(line => line is "remove");
 
         Assert.Equal(longLine, builder.ToString());
     }
@@ -457,7 +457,7 @@ public void FilterLines_ChunkBoundaryInMiddleOfLine()
         builder.Append(fullLine);
         builder.Append("\nafter");
 
-        builder.FilterLines(line => line == "before");
+        builder.FilterLines(line => line is "before");
 
         Assert.Equal(fullLine + "\nafter", builder.ToString());
     }
@@ -471,7 +471,7 @@ public void FilterLines_EmptyLinesAroundChunkBoundaries()
         builder.Append("\n\n\n");
         builder.Append("keep");
 
-        builder.FilterLines(string.IsNullOrEmpty);
+        builder.FilterLines(_ => _.IsWhiteSpace());
 
         Assert.Equal(longLine + "\nkeep", builder.ToString());
     }

src/Verify/Extensions.cs

@@ -152,44 +152,26 @@ public static string NameWithParent(this Type type)
         return null;
     }
 
-    // public static void FilterLines(this StringBuilder input, Func<string, bool> removeLine) =>
-    //     FilterLines(input, (CharSpan line) => removeLine(line.ToString()));
-
     public static void FilterLines(this StringBuilder input, RemoveLine removeLine)
     {
-        if (input.Length == 0)
-        {
-            return;
-        }
+        var theString = input.ToString();
+        using var reader = new StringReader(theString);
+        input.Clear();
 
-        var length = input.Length;
-        var pool = ArrayPool<char>.Shared;
-        var array = pool.Rent(length);
-
-        try
+        while (reader.ReadLine() is { } line)
         {
-            input.CopyTo(0, array, 0, length);
-            var span = array.AsSpan(0, length);
-            var hasTrailingNewline = span[^1] == '\n';
-
-            input.Clear();
-
-            foreach (var line in span.EnumerateLines())
+            if (removeLine(line))
             {
-                if (!removeLine(line))
-                {
-                    input.AppendLineN(line);
-                }
+                continue;
             }
 
-            if (input.Length > 0 && !hasTrailingNewline)
-            {
-                input.Length--;
-            }
+            input.AppendLineN(line);
         }
-        finally
+
+        var endsWithNewLine = theString.EndsWith('\n');
+        if (input.Length > 0 && !endsWithNewLine)
         {
-            pool.Return(array);
+            input.Length -= 1;
         }
     }