Mark generated source as auto-generated and suppress warnings in .g.cs output (#51)

* Initial plan

* Mark generated files and suppress warnings

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

Author: Copilot

EasySourceGenerators.Generators/GeneratesMethodPatternSourceBuilder.cs

@@ -261,6 +261,11 @@ private static string GenerateSwitchMethodSource(
 
     private static void AppendNamespaceAndTypeHeader(StringBuilder builder, INamedTypeSymbol containingType, IMethodSymbol partialMethod)
     {
+        builder.AppendLine("// <auto-generated/>");
+        builder.AppendLine($"// Generated by {typeof(GeneratesMethodGenerator).FullName} for method '{partialMethod.Name}'.");
+        builder.AppendLine("#pragma warning disable");
+        builder.AppendLine();
+
         string? namespaceName = containingType.ContainingNamespace?.IsGlobalNamespace == false
             ? containingType.ContainingNamespace.ToDisplayString()
             : null;

EasySourceGenerators.Tests/BoolSwitchKeyTests.cs

@@ -37,6 +37,16 @@ public static partial string GetBoolLabel(bool flag)
 
         Assert.That(generatedCode, Is.EqualTo(expectedCode));
     }
+
+    [Test]
+    public void BoolSwitchKey_GeneratedCode_HasAutoGeneratedHeaderAndWarningSuppression()
+    {
+        string generatedCode = GeneratedCodeTestHelper.ReadGeneratedCodeRaw("TestBoolSwitchClass_GetBoolLabel.g.cs");
+
+        Assert.That(generatedCode, Does.StartWith("// <auto-generated/>"));
+        Assert.That(generatedCode, Does.Contain("Generated by EasySourceGenerators.Generators.GeneratesMethodGenerator for method 'GetBoolLabel'"));
+        Assert.That(generatedCode, Does.Contain("#pragma warning disable"));
+    }
 }
 
 public static partial class TestBoolSwitchClass

EasySourceGenerators.Tests/GeneratedCodeTestHelper.cs

@@ -5,11 +5,40 @@ internal static class GeneratedCodeTestHelper
     private const char UnicodeBom = '\uFEFF';
 
     internal static string ReadGeneratedCode(string generatedFileName)
+    {
+        string rawCode = ReadGeneratedCodeRaw(generatedFileName);
+        return StripGeneratedPreamble(rawCode);
+    }
+
+    internal static string ReadGeneratedCodeRaw(string generatedFileName)
     {
         string generatedCodePath = GetGeneratedCodePath(generatedFileName);
         return File.ReadAllText(generatedCodePath).TrimStart(UnicodeBom).ReplaceLineEndings("\n").TrimEnd();
     }
 
+    private static string StripGeneratedPreamble(string generatedCode)
+    {
+        string[] lines = generatedCode.Split('\n');
+        int index = 0;
+
+        while (index < lines.Length)
+        {
+            string currentLine = lines[index];
+            bool isGeneratedPreambleLine = currentLine.StartsWith("//", StringComparison.Ordinal)
+                || currentLine.StartsWith("#pragma warning disable", StringComparison.Ordinal)
+                || string.IsNullOrWhiteSpace(currentLine);
+
+            if (!isGeneratedPreambleLine)
+            {
+                break;
+            }
+
+            index++;
+        }
+
+        return string.Join('\n', lines[index..]).TrimEnd();
+    }
+
     private static string GetGeneratedCodePath(string generatedFileName)
     {
         string projectDirectory = FindProjectDirectory();