Add null protection

src/GitVersion.LibGit2Sharp/Git/Branch.cs

@@ -1,3 +1,4 @@
+using GitVersion.Extensions;
 using GitVersion.Helpers;
 
 namespace GitVersion;
@@ -11,7 +12,7 @@ internal sealed class Branch : IBranch
 
     internal Branch(LibGit2Sharp.Branch branch)
     {
-        this.innerBranch = branch;
+        this.innerBranch = branch.NotNull();
         Name = new ReferenceName(branch.CanonicalName);
 
         var commit = this.innerBranch.Tip;
@@ -20,19 +21,17 @@ internal Branch(LibGit2Sharp.Branch branch)
         var commits = this.innerBranch.Commits;
         Commits = commits is null ? null : new CommitCollection(commits);
     }
+
     public ReferenceName Name { get; }
     public ICommit? Tip { get; }
     public ICommitCollection? Commits { get; }
-
     public int CompareTo(IBranch other) => comparerHelper.Compare(this, other);
     public bool Equals(IBranch? other) => equalityHelper.Equals(this, other);
+    public bool IsDetachedHead => Name.Canonical.Equals("(no branch)", StringComparison.OrdinalIgnoreCase);
+    public bool IsRemote => this.innerBranch.IsRemote;
+    public bool IsTracking => this.innerBranch.IsTracking;
     public override bool Equals(object obj) => Equals((obj as IBranch));
     public override int GetHashCode() => equalityHelper.GetHashCode(this);
     public override string ToString() => Name.ToString();
     public static implicit operator LibGit2Sharp.Branch(Branch d) => d.innerBranch;
-
-    public bool IsDetachedHead => Name.Canonical.Equals("(no branch)", StringComparison.OrdinalIgnoreCase);
-
-    public bool IsRemote => this.innerBranch.IsRemote;
-    public bool IsTracking => this.innerBranch.IsTracking;
 }

src/GitVersion.LibGit2Sharp/Git/BranchCollection.cs

@@ -1,23 +1,47 @@
+using GitVersion.Extensions;
+using LibGit2Sharp;
+
 namespace GitVersion;
 
 internal sealed class BranchCollection : IBranchCollection
 {
     private readonly LibGit2Sharp.BranchCollection innerCollection;
-    internal BranchCollection(LibGit2Sharp.BranchCollection collection) => this.innerCollection = collection;
 
-    public IEnumerator<IBranch> GetEnumerator() => this.innerCollection.Select(branch => new Branch(branch)).GetEnumerator();
+    internal BranchCollection(LibGit2Sharp.BranchCollection collection)
+        => this.innerCollection = collection.NotNull();
+
+    public IEnumerator<IBranch> GetEnumerator()
+        => this.innerCollection.Select(branch => new Branch(branch)).GetEnumerator();
+
     IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
     public IBranch? this[string name]
     {
         get
         {
+            name = name.NotNull();
             var branch = this.innerCollection[name];
             return branch is null ? null : new Branch(branch);
         }
     }
 
-    public IEnumerable<IBranch> ExcludeBranches(IEnumerable<IBranch> branchesToExclude) =>
-        this.Where(b => branchesToExclude.All(bte => !b.Equals(bte)));
-    public void UpdateTrackedBranch(IBranch branch, string remoteTrackingReferenceName) =>
-        this.innerCollection.Update((Branch)branch, b => b.TrackedBranch = remoteTrackingReferenceName);
+    public IEnumerable<IBranch> ExcludeBranches(IEnumerable<IBranch> branchesToExclude)
+    {
+        branchesToExclude = branchesToExclude.NotNull();
+
+        bool BranchIsNotExcluded(IBranch branch)
+            => branchesToExclude.All(branchToExclude => !branch.Equals(branchToExclude));
+
+        return this.Where(BranchIsNotExcluded);
+    }
+
+    public void UpdateTrackedBranch(IBranch branch, string remoteTrackingReferenceName)
+    {
+        var branchToUpdate = (Branch)branch.NotNull();
+
+        void Updater(BranchUpdater branchUpdater) =>
+            branchUpdater.TrackedBranch = remoteTrackingReferenceName;
+
+        this.innerCollection.Update(branchToUpdate, Updater);
+    }
 }

src/GitVersion.LibGit2Sharp/Git/Commit.cs

@@ -1,3 +1,4 @@
+using GitVersion.Extensions;
 using GitVersion.Helpers;
 
 namespace GitVersion;
@@ -11,20 +12,18 @@ internal sealed class Commit : GitObject, ICommit
 
     internal Commit(LibGit2Sharp.Commit innerCommit) : base(innerCommit)
     {
-        this.innerCommit = innerCommit;
+        this.innerCommit = innerCommit.NotNull();
         Parents = innerCommit.Parents.Select(parent => new Commit(parent));
         When = innerCommit.Committer.When;
     }
 
     public int CompareTo(ICommit other) => comparerHelper.Compare(this, other);
     public bool Equals(ICommit? other) => equalityHelper.Equals(this, other);
+    public IEnumerable<ICommit> Parents { get; }
+    public DateTimeOffset When { get; }
+    public string Message => this.innerCommit.Message;
     public override bool Equals(object obj) => Equals((obj as ICommit));
     public override int GetHashCode() => equalityHelper.GetHashCode(this);
     public override string ToString() => $"{Id.ToString(7)} {this.innerCommit.MessageShort}";
     public static implicit operator LibGit2Sharp.Commit(Commit d) => d.innerCommit;
-
-    public IEnumerable<ICommit> Parents { get; }
-    public DateTimeOffset When { get; }
-
-    public string Message => this.innerCommit.Message;
 }

src/GitVersion.LibGit2Sharp/Git/CommitCollection.cs

@@ -1,17 +1,22 @@
+using GitVersion.Extensions;
 using LibGit2Sharp;
 
 namespace GitVersion;
 
 internal sealed class CommitCollection : ICommitCollection
 {
     private readonly ICommitLog innerCollection;
-    internal CommitCollection(ICommitLog collection) => this.innerCollection = collection;
 
-    public IEnumerator<ICommit> GetEnumerator() => this.innerCollection.Select(commit => new Commit(commit)).GetEnumerator();
+    internal CommitCollection(ICommitLog collection) => this.innerCollection = collection.NotNull();
+
+    public IEnumerator<ICommit> GetEnumerator()
+        => this.innerCollection.Select(commit => new Commit(commit)).GetEnumerator();
 
     IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
 
-    public IEnumerable<ICommit> GetCommitsPriorTo(DateTimeOffset olderThan) => this.SkipWhile(c => c.When > olderThan);
+    public IEnumerable<ICommit> GetCommitsPriorTo(DateTimeOffset olderThan)
+        => this.SkipWhile(c => c.When > olderThan);
+
     public IEnumerable<ICommit> QueryBy(CommitFilter commitFilter)
     {
         static object? GetReacheableFrom(object? item) =>
@@ -24,13 +29,7 @@ public IEnumerable<ICommit> QueryBy(CommitFilter commitFilter)
 
         var includeReachableFrom = GetReacheableFrom(commitFilter.IncludeReachableFrom);
         var excludeReachableFrom = GetReacheableFrom(commitFilter.ExcludeReachableFrom);
-        var filter = new LibGit2Sharp.CommitFilter
-        {
-            IncludeReachableFrom = includeReachableFrom,
-            ExcludeReachableFrom = excludeReachableFrom,
-            FirstParentOnly = commitFilter.FirstParentOnly,
-            SortBy = (LibGit2Sharp.CommitSortStrategies)commitFilter.SortBy
-        };
+        var filter = new LibGit2Sharp.CommitFilter { IncludeReachableFrom = includeReachableFrom, ExcludeReachableFrom = excludeReachableFrom, FirstParentOnly = commitFilter.FirstParentOnly, SortBy = (LibGit2Sharp.CommitSortStrategies)commitFilter.SortBy };
         var commitLog = ((IQueryableCommitLog)this.innerCollection).QueryBy(filter);
         return new CommitCollection(commitLog);
     }

src/GitVersion.LibGit2Sharp/Git/GitObject.cs

@@ -1,3 +1,4 @@
+using GitVersion.Extensions;
 using GitVersion.Helpers;
 
 namespace GitVersion;
@@ -9,6 +10,7 @@ internal class GitObject : IGitObject
 
     internal GitObject(LibGit2Sharp.GitObject innerGitObject)
     {
+        innerGitObject = innerGitObject.NotNull();
         Id = new ObjectId(innerGitObject.Id);
         Sha = innerGitObject.Sha;
     }