.

Author: SimonCropp

src/Verify.Tests/LinesScrubberTests.cs

@@ -83,7 +83,7 @@ public void FilterLines_RemovesSingleLine()
     {
         var builder = new StringBuilder("line1\nline2\nline3");
 
-        builder.FilterLines(line => line == "line2");
+        builder.FilterLines(line => line is "line2");
 
         Assert.Equal("line1\nline3", builder.ToString());
     }
@@ -154,7 +154,7 @@ public void FilterLines_PreservesTrailingNewline()
     {
         var builder = new StringBuilder("line1\nline2\n");
 
-        builder.FilterLines(line => line == "line2");
+        builder.FilterLines(line => line is "line2");
 
         Assert.Equal("line1\n", builder.ToString());
     }
@@ -164,7 +164,7 @@ public void FilterLines_DoesNotAddTrailingNewlineWhenOriginalLacked()
     {
         var builder = new StringBuilder("line1\nline2");
 
-        builder.FilterLines(line => line == "line1");
+        builder.FilterLines(line => line is "line1");
 
         Assert.Equal("line2", builder.ToString());
     }
@@ -174,7 +174,7 @@ public void FilterLines_HandlesEmptyLines()
     {
         var builder = new StringBuilder("line1\n\nline3");
 
-        builder.FilterLines(string.IsNullOrEmpty);
+        builder.FilterLines(line => line.Length == 0);
 
         Assert.Equal("line1\nline3", builder.ToString());
     }
@@ -184,7 +184,7 @@ public void FilterLines_KeepsEmptyLines()
     {
         var builder = new StringBuilder("line1\n\nline3");
 
-        builder.FilterLines(line => line == "line1");
+        builder.FilterLines(line => line is "line1");
 
         Assert.Equal("\nline3", builder.ToString());
     }
@@ -204,7 +204,7 @@ public void FilterLines_RemovesFirstLine()
     {
         var builder = new StringBuilder("remove\nkeep1\nkeep2");
 
-        builder.FilterLines(line => line == "remove");
+        builder.FilterLines(line => line is "remove");
 
         Assert.Equal("keep1\nkeep2", builder.ToString());
     }
@@ -214,7 +214,7 @@ public void FilterLines_RemovesLastLine()
     {
         var builder = new StringBuilder("keep1\nkeep2\nremove");
 
-        builder.FilterLines(line => line == "remove");
+        builder.FilterLines(line => line is "remove");
 
         Assert.Equal("keep1\nkeep2", builder.ToString());
     }
@@ -224,7 +224,7 @@ public void FilterLines_RemovesLastLineWithTrailingNewline()
     {
         var builder = new StringBuilder("keep1\nkeep2\nremove\n");
 
-        builder.FilterLines(line => line == "remove");
+        builder.FilterLines(line => line is "remove");
 
         Assert.Equal("keep1\nkeep2\n", builder.ToString());
     }
@@ -234,7 +234,19 @@ public void FilterLines_ComplexPredicate()
     {
         var builder = new StringBuilder("abc123\ndef456\nghi789\njkl012");
 
-        builder.FilterLines(line => line.Any(char.IsDigit) && line.Contains('4'));
+        builder.FilterLines(line =>
+        {
+            var hasDigit = false;
+            foreach (var c in line)
+            {
+                if (char.IsDigit(c))
+                {
+                    hasDigit = true;
+                    break;
+                }
+            }
+            return hasDigit && line.Contains('4');
+        });
 
         Assert.Equal("abc123\nghi789\njkl012", builder.ToString());
     }
@@ -244,7 +256,7 @@ public void FilterLines_WindowsLineEndings()
     {
         var builder = new StringBuilder("line1\r\nline2\r\nline3");
 
-        builder.FilterLines(line => line == "line2");
+        builder.FilterLines(line => line is "line2");
 
         // Note: StringReader normalizes \r\n to \n
         Assert.Equal("line1\nline3", builder.ToString());
@@ -255,7 +267,7 @@ public void FilterLines_MixedLineEndings()
     {
         var builder = new StringBuilder("line1\nline2\r\nline3");
 
-        builder.FilterLines(line => line == "line2");
+        builder.FilterLines(line => line is "line2");
 
         Assert.Equal("line1\nline3", builder.ToString());
     }
@@ -266,7 +278,7 @@ public void FilterLines_LargeContent()
         var lines = Enumerable.Range(1, 1000).Select(i => $"line{i}");
         var builder = new StringBuilder(string.Join('\n', lines));
 
-        builder.FilterLines(line => int.Parse(line[4..]) % 2 == 0);
+        builder.FilterLines(line => int.Parse(line.Slice(4)) % 2 == 0);
 
         var remaining = builder.ToString().Split('\n');
         Assert.Equal(500, remaining.Length);
@@ -278,7 +290,7 @@ public void FilterLines_PreservesWhitespace()
     {
         var builder = new StringBuilder("  line1  \n\t line2\t\nline3   ");
 
-        builder.FilterLines(line => line.Trim() == "line2");
+        builder.FilterLines(line => line.Trim() is "line2");
 
         Assert.Equal("  line1  \nline3   ", builder.ToString());
     }

src/Verify/Extensions.cs

@@ -157,27 +157,24 @@ public static string NameWithParent(this Type type)
 
     public static void FilterLines(this StringBuilder input, RemoveLine removeLine)
     {
-        if (input.Length == 0)
-        {
-            return;
-        }
-
-        var span = input.AsSpan();
-        var hasTrailingNewline = span[^1] == '\n';
-
+        var theString = input.ToString();
+        using var reader = new StringReader(theString);
         input.Clear();
 
-        foreach (var line in span.EnumerateLines())
+        while (reader.ReadLine() is { } line)
         {
-            if (!removeLine(line))
+            if (removeLine(line))
             {
-                input.AppendLineN(line);
+                continue;
             }
+
+            input.AppendLineN(line);
         }
 
-        if (input.Length > 0 && !hasTrailingNewline)
+        var endsWithNewLine = theString.EndsWith('\n');
+        if (input.Length > 0 && !endsWithNewLine)
         {
-            input.Length--;
+            input.Length -= 1;
         }
     }