Detect NoWarn NU1701 in SDK project discovery and warn during report

Add HasNoWarnNU1701 property to ProjectDiscoveryResult that is set during
SDK project discovery when the NoWarn property contains NU1701. The warning
is reported once per project during ReportDiscovery using a fully normalized
rooted path in sorted order.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: brettfo

nuget/helpers/lib/NuGetUpdater/NuGetUpdater.Core.Test/Utilities/LoggerTests.cs

@@ -4,6 +4,8 @@
 using System.Text;
 using System.Threading.Tasks;
 
+using NuGetUpdater.Core.Discover;
+
 using Xunit;
 using Xunit.Sdk;
 
@@ -56,5 +58,47 @@ public void LogRaw_ShouldStreamLogsIndividually()
         Assert.Contains(testMessage2, output);
     }
 
+    [Fact]
+    public void ReportDiscovery_LogsWarningForProjectsWithNU1701()
+    {
+        var logger = new StringLogger();
+        var discoveryResult = new WorkspaceDiscoveryResult()
+        {
+            Path = "/src",
+            Projects = [
+                new()
+                {
+                    FilePath = "zebra.csproj",
+                    Dependencies = [],
+                    ImportedFiles = [],
+                    AdditionalFiles = [],
+                    HasNoWarnNU1701 = true,
+                },
+                new()
+                {
+                    FilePath = "middle.csproj",
+                    Dependencies = [],
+                    ImportedFiles = [],
+                    AdditionalFiles = [],
+                    HasNoWarnNU1701 = false,
+                },
+                new()
+                {
+                    FilePath = "alpha.csproj",
+                    Dependencies = [],
+                    ImportedFiles = [],
+                    AdditionalFiles = [],
+                    HasNoWarnNU1701 = true,
+                },
+            ]
+        };
+
+        logger.ReportDiscovery(discoveryResult);
 
+        var warnings = logger.Messages.Where(m => m.Contains("has NoWarn property containing NU1701; package compatibility checks may be inaccurate.")).ToList();
+        Assert.Equal(2, warnings.Count);
+        Assert.Contains("/src/alpha.csproj", warnings[0]);
+        Assert.Contains("/src/zebra.csproj", warnings[1]);
+        Assert.DoesNotContain(logger.Messages, m => m.Contains("Project [/src/middle.csproj] has NoWarn property containing NU1701; package compatibility checks may be inaccurate."));
+    }
 }

nuget/helpers/lib/NuGetUpdater/NuGetUpdater.Core/Discover/ProjectDiscoveryResult.cs

@@ -16,4 +16,5 @@ public record ProjectDiscoveryResult : IDiscoveryResultWithDependencies
     public required ImmutableArray<string> ImportedFiles { get; init; }
     public required ImmutableArray<string> AdditionalFiles { get; init; }
     public required ImmutableArray<Dependency> Dependencies { get; init; }
+    public bool HasNoWarnNU1701 { get; init; } = false;
 }

nuget/helpers/lib/NuGetUpdater/NuGetUpdater.Core/Discover/SdkProjectDiscovery.cs

@@ -674,6 +674,18 @@ PackageManagementKind.CentralPackageManagement or
                 packageManagementKind = PackageManagementKind.Default;
             }
 
+            // check for NoWarn containing NU1701
+            var noWarnValue = GetStringPropertyFromProjectProperties(projectProperties, "NoWarn");
+            var hasNoWarnNU1701 = false;
+            if (noWarnValue is not null)
+            {
+                var noWarnCodes = noWarnValue.Split(';', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+                if (noWarnCodes.Contains("NU1701", StringComparer.OrdinalIgnoreCase))
+                {
+                    hasNoWarnNU1701 = true;
+                }
+            }
+
             var projectDiscoveryResult = new ProjectDiscoveryResult()
             {
                 FilePath = projectRelativePath,
@@ -684,6 +696,7 @@ PackageManagementKind.CentralPackageManagement or
                 AdditionalFiles = additional,
                 PackageManagementKind = packageManagementKind,
                 PackageManagementSpecialFileRelativePath = packageManagementFile,
+                HasNoWarnNU1701 = hasNoWarnNU1701,
             };
             projectDiscoveryResults.Add(projectDiscoveryResult);
         }

nuget/helpers/lib/NuGetUpdater/NuGetUpdater.Core/Utilities/ILogger.cs

@@ -24,6 +24,16 @@ public static void ReportAnalysis(this ILogger logger, AnalysisResult analysisRe
 
     public static void ReportDiscovery(this ILogger logger, WorkspaceDiscoveryResult discoveryResult)
     {
+        var nu1701Projects = discoveryResult.Projects
+            .Where(p => p.HasNoWarnNU1701)
+            .Select(p => PathHelper.JoinPath(discoveryResult.Path, p.FilePath).FullyNormalizedRootedPath())
+            .OrderBy(p => p, StringComparer.OrdinalIgnoreCase)
+            .ToList();
+        foreach (var projectPath in nu1701Projects)
+        {
+            logger.Warn($"Project [{projectPath}] has NoWarn property containing NU1701; package compatibility checks may be inaccurate.");
+        }
+
         logger.Info("Discovery JSON content:");
         logger.Info(JsonSerializer.Serialize(discoveryResult, DiscoveryWorker.SerializerOptions));
     }