Merge pull request #644 from dotnet/IsNull

Apply `is null` pattern and analyzer

Author: AArnott

.editorconfig

@@ -79,3 +79,9 @@ csharp_new_line_before_catch = true
 csharp_new_line_before_finally = true
 csharp_new_line_before_members_in_object_initializers = true
 csharp_new_line_before_members_in_anonymous_types = true
+
+# CSIsNull001: Use `is null` for null checks
+dotnet_diagnostic.CSIsNull001.severity = warning
+
+# CSIsNull002: Use `is object` for non-null checks
+dotnet_diagnostic.CSIsNull002.severity = warning

src/Directory.Build.props

@@ -24,9 +24,13 @@
     <LibGit2SharpNativeVersion>2.0.312</LibGit2SharpNativeVersion>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="Microsoft.Net.Compilers.Toolset" Version="3.8.0-5.final" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.Net.Compilers.Toolset" Version="3.11.0" PrivateAssets="all" />
     <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0" PrivateAssets="All" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
+    <PackageReference Include="CSharpIsNullAnalyzer" Version="0.1.288-beta">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
+    </PackageReference>
   </ItemGroup>
   <ItemGroup>
     <None Include="$(MSBuildThisFileDirectory)..\3rdPartyNotices.txt" Pack="true" PackagePath="" />

src/NerdBank.GitVersioning.Tests/BuildIntegrationTests.cs

@@ -219,7 +219,7 @@ public async Task GetBuildVersion_In_Git_But_Head_Lacks_VersionFile()
         var repo = new Repository(this.RepoPath); // do not assign Repo property to avoid commits being generated later
         repo.Commit("empty", this.Signer, this.Signer, new CommitOptions { AllowEmptyCommit = true });
         this.WriteVersionFile("3.4");
-        Assumes.True(repo.Index[VersionFile.JsonFileName] == null);
+        Assumes.True(repo.Index[VersionFile.JsonFileName] is null);
         var buildResult = await this.BuildAsync();
         Assert.Equal("3.4.0." + this.GetVersion().Revision, buildResult.BuildVersion);
         Assert.Equal("3.4.0+" + repo.Head.Tip.Id.Sha.Substring(0, VersionOptions.DefaultGitCommitIdShortFixedLength), buildResult.AssemblyInformationalVersion);

src/NerdBank.GitVersioning.Tests/ManagedGit/DeltaStreamReaderTests.cs

@@ -89,7 +89,7 @@ public void ReadStreamTest()
 
                 DeltaInstruction? current;
 
-                while ((current = DeltaStreamReader.Read(stream)) != null)
+                while ((current = DeltaStreamReader.Read(stream)) is not null)
                 {
                     instructions.Add(current.Value);
                 }
@@ -139,7 +139,7 @@ public void ReadStreamTest_Memory()
 
             DeltaInstruction? current;
 
-            while ((current = DeltaStreamReader.Read(ref memory)) != null)
+            while ((current = DeltaStreamReader.Read(ref memory)) is not null)
             {
                 instructions.Add(current.Value);
             }

src/NerdBank.GitVersioning.Tests/ReleaseManagerTests.cs

@@ -320,7 +320,7 @@ public void PrepareRelease_Master(
 
         // prepare release
         var releaseManager = new ReleaseManager();
-        releaseManager.PrepareRelease(this.RepoPath, releaseUnstableTag, (nextVersion == null ? null : Version.Parse(nextVersion)), parameterVersionIncrement);
+        releaseManager.PrepareRelease(this.RepoPath, releaseUnstableTag, (nextVersion is null ? null : Version.Parse(nextVersion)), parameterVersionIncrement);
 
         // check if a branch was created
         Assert.Contains(this.LibGit2Repository.Branches, branch => branch.FriendlyName == expectedBranchName);
@@ -394,7 +394,7 @@ public void PrepareRelease_MasterWithVersionDecrement(string initialVersion, str
         // running PrepareRelease should result in an error
         // because we're trying to add a prerelease tag to a version without prerelease tag
         this.AssertError(
-            () => new ReleaseManager().PrepareRelease(this.RepoPath, releaseUnstableTag, (nextVersion == null ? null : Version.Parse(nextVersion))),
+            () => new ReleaseManager().PrepareRelease(this.RepoPath, releaseUnstableTag, (nextVersion is null ? null : Version.Parse(nextVersion))),
             ReleasePreparationError.VersionDecrement);
     }
 

src/NerdBank.GitVersioning.Tests/RepoTestBase.cs

@@ -143,7 +143,7 @@ protected void AddCommits(int count = 1)
 
     protected Commit? WriteVersionTxtFile(string version = "1.2", string prerelease = "", string? relativeDirectory = null)
     {
-        if (relativeDirectory == null)
+        if (relativeDirectory is null)
         {
             relativeDirectory = string.Empty;
         }
@@ -163,7 +163,7 @@ protected void AddCommits(int count = 1)
     {
         Requires.NotNull(versionData, nameof(versionData));
 
-        if (relativeDirectory == null)
+        if (relativeDirectory is null)
         {
             relativeDirectory = string.Empty;
         }
@@ -197,7 +197,7 @@ protected void AddCommits(int count = 1)
             if (Path.GetExtension(relativeFilePath) == ".json")
             {
                 string txtFilePath = relativeFilePath.Substring(0, relativeFilePath.Length - 4) + "txt";
-                if (!File.Exists(Path.Combine(this.RepoPath, txtFilePath)) && this.LibGit2Repository.Index[txtFilePath] != null)
+                if (!File.Exists(Path.Combine(this.RepoPath, txtFilePath)) && this.LibGit2Repository.Index[txtFilePath] is not null)
                 {
                     this.LibGit2Repository.Index.Remove(txtFilePath);
                 }

src/NerdBank.GitVersioning.Tests/TestUtilities.cs

@@ -54,7 +54,7 @@ internal static void ExtractEmbeddedResource(string resourcePath, string extract
 
         using (var stream = GetEmbeddedResource(resourcePath))
         {
-            Requires.Argument(stream != null, nameof(resourcePath), "Resource not found.");
+            Requires.Argument(stream is not null, nameof(resourcePath), "Resource not found.");
             using (var extractedFile = File.OpenWrite(extractedFilePath))
             {
                 stream.CopyTo(extractedFile);

src/NerdBank.GitVersioning.Tests/VersionFileTests.cs

@@ -140,7 +140,7 @@ public void SetVersion_WritesSimplestFile(string version, string assemblyVersion
         var versionOptions = new VersionOptions
         {
             Version = SemanticVersion.Parse(version),
-            AssemblyVersion = assemblyVersion != null || precision != null ? new VersionOptions.AssemblyVersionOptions(assemblyVersion != null ? new Version(assemblyVersion) : null, precision) : null,
+            AssemblyVersion = assemblyVersion is not null || precision is not null ? new VersionOptions.AssemblyVersionOptions(assemblyVersion is not null ? new Version(assemblyVersion) : null, precision) : null,
             VersionHeightOffset = versionHeightOffset,
             Inherit = inherit,
         };

src/NerdBank.GitVersioning/AssemblyVersionOptionsConverter.cs

@@ -51,7 +51,7 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
         public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
         {
             var data = value as VersionOptions.AssemblyVersionOptions;
-            if (data != null)
+            if (data is not null)
             {
                 if (data.PrecisionOrDefault == VersionOptions.DefaultVersionPrecision && !this.includeDefaults)
                 {

src/NerdBank.GitVersioning/CloudBuildServices/GitLab.cs

@@ -14,13 +14,13 @@
     internal class GitLab : ICloudBuild
     {
         public string BuildingBranch =>
-            Environment.GetEnvironmentVariable("CI_COMMIT_TAG") == null ? 
+            Environment.GetEnvironmentVariable("CI_COMMIT_TAG") is null ? 
                 $"refs/heads/{Environment.GetEnvironmentVariable("CI_COMMIT_REF_NAME")}" : null;
 
         public string BuildingRef => this.BuildingBranch ?? this.BuildingTag;
 
         public string BuildingTag =>
-            Environment.GetEnvironmentVariable("CI_COMMIT_TAG") != null ?
+            Environment.GetEnvironmentVariable("CI_COMMIT_TAG") is not null ?
                 $"refs/tags/{Environment.GetEnvironmentVariable("CI_COMMIT_TAG")}" : null;
 
         public string GitCommitId => Environment.GetEnvironmentVariable("CI_COMMIT_SHA");