Enable support for milestone-based issues queries (#1788)

* Added support for Milestone filter in SearchIssuesRequest

* Fixed some styling issues to match with the style of the existing code

* Wrap milestone value with double quotes as milestones can contain spaces

* Allow milestone filter to contain double quotes

* Ability to search by milestone exclusions

* Moved the EscapeDoubleQuotes method to StringExtensions

Octokit/Models/Request/SearchIssuesRequest.cs

@@ -1,11 +1,11 @@
-using System;
+using Octokit.Internal;
+using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Linq;
-using Octokit.Internal;
 
 namespace Octokit
 {
@@ -168,6 +168,7 @@ namespace Octokit
         public Language? Language { get; set; }
 
         private IEnumerable<IssueIsQualifier> _is;
+
         /// <summary>
         /// Searches for issues using a more human syntax covering options like state, type, merged status, private/public repository
         /// </summary>
@@ -258,6 +259,11 @@ namespace Octokit
         /// </remarks>
         public string User { get; set; }
 
+        /// <summary>
+        /// Gets or sets the milestone to filter issues based on
+        /// </summary>
+        public string Milestone { get; set; }
+
         [SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
         public RepositoryCollection Repos { get; set; }
 
@@ -391,6 +397,11 @@ namespace Octokit
                 parameters.AddRange(Repos.Select(x => string.Format(CultureInfo.InvariantCulture, "repo:{0}", x)));
             }
 
+            if (Milestone.IsNotBlank())
+            {
+                parameters.Add(string.Format(CultureInfo.InvariantCulture, "milestone:\"{0}\"", Milestone.EscapeDoubleQuotes()));
+            }
+
             // Add any exclusion parameters
             if (Exclusions != null)
             {

Octokit/Models/Request/SearchIssuesRequestExclusions.cs

@@ -1,11 +1,9 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Linq;
-using Octokit.Internal;
 
 namespace Octokit
 {
@@ -122,6 +120,14 @@ namespace Octokit
         /// </remarks>
         public string Base { get; set; }
 
+        /// <summary>
+        /// Excludes issues which target the specified milestone.
+        /// </summary>
+        /// <remarks>
+        /// https://help.github.com/articles/searching-issues-and-pull-requests/#search-by-milestone-on-an-issue-or-pull-request
+        /// </remarks>
+        public string Milestone { get; set; }
+
         [SuppressMessage("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity")]
         public IReadOnlyList<string> MergedQualifiers()
         {
@@ -182,6 +188,11 @@ namespace Octokit
                 parameters.Add(string.Format(CultureInfo.InvariantCulture, "-base:{0}", Base));
             }
 
+            if (Milestone.IsNotBlank())
+            {
+                parameters.Add(string.Format(CultureInfo.InvariantCulture, "-milestone:\"{0}\"", Milestone.EscapeDoubleQuotes()));
+            }
+
             return new ReadOnlyCollection<string>(parameters);
         }