Support IReadOnlySet. Refactor out method that determines most suitab…

…le type for collections that are already specified in the destination.
dotnet · tarekgh · Jul 19, 2022 · Apr 17, 2022 · Apr 17, 2022 · Apr 18, 2022
commit 65ea98924106d8c5f2925a1307464bd4d3bb279a
diff --git a/src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs b/src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs
@@ -4,6 +4,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.ComponentModel;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
@@ -303,11 +304,14 @@ private static object BindToCollection(Type type, IConfiguration config, BinderO
                 return instance;
             }
 
-            collectionInterface = FindOpenGenericInterface(typeof(IReadOnlyCollection<>), type);
+            collectionInterface = FindOpenGenericInterface(typeof(ISet<>), type);
+#if NET5_0_OR_GREATER
+            collectionInterface ??= FindOpenGenericInterface(typeof(IReadOnlySet<>), type);
+#endif
             if (collectionInterface != null)
             {
-                // IReadOnlyCollection<T> is guaranteed to have exactly one parameter
-                return BindToCollection(type, config, options);
+                // ISet<T> is guaranteed to have exactly one parameter
+                return BindToSet(type, config, options);
             }
 
             collectionInterface = FindOpenGenericInterface(typeof(ICollection<>), type);
@@ -615,7 +619,11 @@ private static Array BindArray(Type type, IEnumerable? source, IConfiguration co
             else // e. g. IEnumerable<T>
             {
                 elementType = type.GetGenericArguments()[0];
-            }
+
+                if ((type = sourceType.GetInterface("IReadOnlySet`1", false)) != null)
+                {
+                    return (typeof(HashSet<>), type.GenericTypeArguments[0]);
+                }
 
             IList list = new List<object?>();
 

diff --git a/src/libraries/Microsoft.Extensions.Configuration.Binder/tests/ConfigurationBinderTests.cs b/src/libraries/Microsoft.Extensions.Configuration.Binder/tests/ConfigurationBinderTests.cs
@@ -56,6 +56,10 @@ public string ReadOnly
 
             public IEnumerable<string> NonInstantiatedIEnumerable { get; set; } = null!;
             public ISet<string> InstantiatedISet { get; set; } = new HashSet<string>();
+            #if NET5_0_OR_GREATER
+            public IReadOnlySet<string> InstantiatedIReadOnlySet { get; set; } = new HashSet<string>();
+            public IReadOnlySet<string> NonInstantiatedIReadOnlySet { get; set; }
+            #endif
             public IEnumerable<string> InstantiatedIEnumerable { get; set; } = new List<string>();
             public ICollection<string> InstantiatedICollection { get; set; } = new List<string>();
             public IReadOnlyCollection<string> InstantiatedIReadOnlyCollection { get; set; } = new List<string>();
@@ -499,11 +503,52 @@ public void CanBindNonInstantiatedISet()
 
             var options = config.Get<ComplexOptions>()!;
 
-            Assert.Equal(2, options.NonInstantiatedISet.Count());
+            Assert.Equal(2, options.NonInstantiatedISet.Count);
             Assert.Equal("Yo1", options.NonInstantiatedISet.ElementAt(0));
             Assert.Equal("Yo2", options.NonInstantiatedISet.ElementAt(1));
         }
 
+#if NET5_0_OR_GREATER
+        [Fact]
+        public void CanBindInstantiatedIReadOnlySet()
+        {
+            var dic = new Dictionary<string, string>
+            {
+                {"InstantiatedIReadOnlySet:0", "Yo1"},
+                {"InstantiatedIReadOnlySet:1", "Yo2"},
+            };
+            var configurationBuilder = new ConfigurationBuilder();
+            configurationBuilder.AddInMemoryCollection(dic);
+
+            var config = configurationBuilder.Build();
+
+            var options = config.Get<ComplexOptions>()!;
+
+            Assert.Equal(2, options.InstantiatedIReadOnlySet.Count);
+            Assert.Equal("Yo1", options.InstantiatedIReadOnlySet.ElementAt(0));
+            Assert.Equal("Yo2", options.InstantiatedIReadOnlySet.ElementAt(1));
+        }
+
+        [Fact]
+        public void CanBindNonInstantiatedIReadOnlySet()
+        {
+            var dic = new Dictionary<string, string>
+            {
+                {"NonInstantiatedIReadOnlySet:0", "Yo1"},
+                {"NonInstantiatedIReadOnlySet:1", "Yo2"},
+            };
+            var configurationBuilder = new ConfigurationBuilder();
+            configurationBuilder.AddInMemoryCollection(dic);
+
+            var config = configurationBuilder.Build();
+
+            var options = config.Get<ComplexOptions>()!;
+
+            Assert.Equal(2, options.NonInstantiatedIReadOnlySet.Count);
+            Assert.Equal("Yo1", options.NonInstantiatedIReadOnlySet.ElementAt(0));
+            Assert.Equal("Yo2", options.NonInstantiatedIReadOnlySet.ElementAt(1));
+        }
+#endif
         [Fact]
         public void CanBindNonInstantiatedDictionaryOfISet()
         {