Improve error handling in case pull request does not exist

src/Cake.Tfs/PullRequest/TfsPullRequest.cs

@@ -25,7 +25,7 @@ public sealed class TfsPullRequest
         /// </summary>
         /// <param name="log">The Cake log context.</param>
         /// <param name="settings">Settings for accessing TFS.</param>
-        /// <exception cref="TfsException">If <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/>
+        /// <exception cref="TfsPullRequestNotFoundException">If <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/>
         /// is set to <c>true</c> and no pull request could be found.</exception>
         public TfsPullRequest(ICakeLog log, TfsPullRequestSettings settings)
         {
@@ -90,7 +90,7 @@ public TfsPullRequest(ICakeLog log, TfsPullRequestSettings settings)
             {
                 if (this.settings.ThrowExceptionIfPullRequestCouldNotBeFound)
                 {
-                    throw new TfsException("Could not find pull request");
+                    throw new TfsPullRequestNotFoundException("Pull request not found");
                 }
 
                 this.log.Warning("Could not find pull request");
@@ -141,7 +141,7 @@ public TfsPullRequest(ICakeLog log, TfsPullRequestSettings settings)
         /// Returns <see cref="Guid.Empty"/> if no pull request could be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>false</c>.
         /// </summary>
-        /// <exception cref="TfsException">If pull request could not be found and
+        /// <exception cref="TfsPullRequestNotFoundException">If pull request could not be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>true</c>.</exception>
         public Guid RepositoryId
         {
@@ -161,7 +161,7 @@ public Guid RepositoryId
         /// Returns 0 if no pull request could be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>false</c>.
         /// </summary>
-        /// <exception cref="TfsException">If pull request could not be found and
+        /// <exception cref="TfsPullRequestNotFoundException">If pull request could not be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>true</c>.</exception>
         public int PullRequestId
         {
@@ -181,7 +181,7 @@ public int PullRequestId
         /// Returns 0 if no pull request could be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>false</c>.
         /// </summary>
-        /// <exception cref="TfsException">If pull request could not be found and
+        /// <exception cref="TfsPullRequestNotFoundException">If pull request could not be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>true</c>.</exception>
         public int CodeReviewId
         {
@@ -201,7 +201,7 @@ public int CodeReviewId
         /// Returns <see cref="string.Empty"/> if no pull request could be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>false</c>.
         /// </summary>
-        /// <exception cref="TfsException">If pull request could not be found and
+        /// <exception cref="TfsPullRequestNotFoundException">If pull request could not be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>true</c>.</exception>
         public string LastSourceCommitId
         {
@@ -220,6 +220,8 @@ public string LastSourceCommitId
         /// Votes for the pullrequest.
         /// </summary>
         /// <param name="vote">The vote for the pull request.</param>
+        /// <exception cref="TfsPullRequestNotFoundException">If pull request could not be found and
+        /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>true</c>.</exception>
         public void Vote(TfsPullRequestVote vote)
         {
             if (!this.ValidatePullRequest())
@@ -249,9 +251,9 @@ public void Vote(TfsPullRequestVote vote)
         /// the pull request instance can be null for subsequent calls.
         /// </summary>
         /// <returns>True if a valid pull request instance exists.</returns>
-        /// <exception cref="TfsException">If <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/>
+        /// <exception cref="TfsPullRequestNotFoundException">If <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/>
         /// is set to <c>true</c> and no pull request could be found.</exception>
-        public bool ValidatePullRequest()
+        private bool ValidatePullRequest()
         {
             if (this.HasPullRequestLoaded)
             {
@@ -260,7 +262,7 @@ public bool ValidatePullRequest()
 
             if (this.settings.ThrowExceptionIfPullRequestCouldNotBeFound)
             {
-                throw new TfsException("Could not find pull request");
+                throw new TfsPullRequestNotFoundException("Pull request not found");
             }
 
             this.log.Verbose("Skipping, since no pull request instance could be found.");

src/Cake.Tfs/PullRequest/TfsPullRequestNotFoundException.cs

@@ -0,0 +1,52 @@
+namespace Cake.Tfs.PullRequest
+{
+    using System;
+    using System.Runtime.Serialization;
+
+    /// <summary>
+    /// Represents an error if a pull request was not found.
+    /// </summary>
+    [Serializable]
+    public class TfsPullRequestNotFoundException : TfsException
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TfsPullRequestNotFoundException"/> class.
+        /// </summary>
+        public TfsPullRequestNotFoundException()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TfsPullRequestNotFoundException"/> class with a specified error message.
+        /// </summary>
+        /// <param name="message">The message that describes the error. </param>
+        public TfsPullRequestNotFoundException(string message)
+            : base(message)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TfsPullRequestNotFoundException"/> class with a specified error message
+        /// and a reference to the inner exception that is the cause of this exception.
+        /// </summary>
+        /// <param name="message">The error message that explains the reason for the exception.</param>
+        /// <param name="innerException">The exception that is the cause of the current exception, or a null
+        /// reference if no inner exception is specified.</param>
+        public TfsPullRequestNotFoundException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TfsPullRequestNotFoundException"/> class with serialized data.
+        /// </summary>
+        /// <param name="info">The <see cref="SerializationInfo"/> that holds the serialized object data about
+        /// the exception being thrown.</param>
+        /// <param name="context">The <see cref="StreamingContext"/> that contains contextual information about
+        /// the source or destination. </param>
+        protected TfsPullRequestNotFoundException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+        }
+    }
+}

src/Cake.Tfs/TfsAliases.PullRequest.cs

@@ -34,7 +34,7 @@ public static partial class TfsAliases
         /// <returns>Description of the pull request.
         /// Returns null if pull request could not be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>false</c>.</returns>
-        /// <exception cref="TfsException">If pull request could not be found and
+        /// <exception cref="TfsPullRequestNotFoundException">If pull request could not be found and
         /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>true</c>.</exception>
         [CakeMethodAlias]
         [CakeAliasCategory("Pull Request")]
@@ -78,6 +78,8 @@ public static TfsPullRequest TfsPullRequest(
         /// ]]>
         /// </code>
         /// </example>
+        /// <exception cref="TfsPullRequestNotFoundException">If pull request could not be found and
+        /// <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/> is set to <c>true</c>.</exception>
         [CakeMethodAlias]
         [CakeAliasCategory("Pull Request")]
         public static void TfsPullRequestVote(
@@ -88,8 +90,7 @@ public static void TfsPullRequestVote(
             context.NotNull(nameof(context));
             settings.NotNull(nameof(settings));
 
-            var pullRequest = new TfsPullRequest(context.Log, settings);
-            pullRequest.Vote(vote);
+            new TfsPullRequest(context.Log, settings).Vote(vote);
         }
     }
 }