From 30edaf73024c5bc5fbe563cbd12c2b8540f49bac Mon Sep 17 00:00:00 2001
From: Smit Patel <smitpatel@users.noreply.github.com>
Date: Thu, 28 Oct 2021 16:17:31 -0700
Subject: [PATCH] Query: Convert IReadOnlyCollection.Count to Queryable.Count()
 (#26483)

Resolves #26433
---
 .../NavigationExpandingExpressionVisitor.cs   |  5 +-
 .../Query/SimpleQueryTestBase.cs              | 68 +++++++++++++++++++
 .../Query/SimpleQuerySqlServerTest.cs         | 39 +++++++++++
 3 files changed, 111 insertions(+), 1 deletion(-)

diff --git a/src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs b/src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs
index 956e9b21955..deed78afc2e 100644
--- a/src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs
+++ b/src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs
@@ -214,7 +214,10 @@ protected override Expression VisitMember(MemberExpression memberExpression)
                 && innerExpression != null
                 && memberExpression.Member.Name == nameof(ICollection<int>.Count)
                 && memberExpression.Expression.Type.GetInterfaces().Append(memberExpression.Expression.Type)
-                    .Any(e => e.IsGenericType && e.GetGenericTypeDefinition() == typeof(ICollection<>)))
+                    .Any(e => e.IsGenericType
+                        && (e.GetGenericTypeDefinition() is Type genericTypeDefinition
+                            && (genericTypeDefinition == typeof(ICollection<>)
+                                || genericTypeDefinition == typeof(IReadOnlyCollection<>)))))
             {
                 var innerQueryable = UnwrapCollectionMaterialization(innerExpression);
 
diff --git a/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.cs b/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.cs
index 90db5cc757e..29f69678271 100644
--- a/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.cs
+++ b/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.cs
@@ -324,5 +324,73 @@ public PhotoBlog()
 
             public int NumberOfPhotos { get; set; }
         }
+
+        [ConditionalTheory]
+        [MemberData(nameof(IsAsyncData))]
+        public virtual async Task Count_member_over_IReadOnlyCollection_works(bool async)
+        {
+            var contextFactory = await InitializeAsync<Context26433>(seed: c => c.Seed());
+            using var context = contextFactory.CreateContext();
+
+            var query = context.Authors
+                    .Select(a => new
+                    {
+                        BooksCount = a.Books.Count
+                    });
+
+            var authors = async
+                ? await query.ToListAsync()
+                : query.ToList();
+
+            Assert.Equal(3, Assert.Single(authors).BooksCount);
+        }
+
+        protected class Context26433 : DbContext
+        {
+            public Context26433(DbContextOptions options)
+                   : base(options)
+            {
+            }
+
+            public DbSet<Book26433> Books { get; set; }
+            public DbSet<Author26433> Authors { get; set; }
+
+            public void Seed()
+            {
+
+                base.Add(new Author26433
+                {
+                    FirstName = "William",
+                    LastName = "Shakespeare",
+                    Books = new List<Book26433>
+                        {
+                            new() {Title = "Hamlet"},
+                            new() {Title = "Othello"},
+                            new() {Title = "MacBeth"}
+                        }
+                });
+
+                SaveChanges();
+            }
+        }
+
+        protected class Author26433
+        {
+            [Key]
+            public int AuthorId { get; set; }
+            public string FirstName { get; set; }
+            public string LastName { get; set; }
+            public IReadOnlyCollection<Book26433> Books { get; set; }
+        }
+
+        protected class Book26433
+        {
+            [Key]
+            public int BookId { get; set; }
+            public string Title { get; set; }
+            public int AuthorId { get; set; }
+            public Author26433 Author { get; set; }
+        }
+
     }
 }
diff --git a/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.cs b/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.cs
index 4fad38a5246..2a6dacbf857 100644
--- a/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.cs
+++ b/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.cs
@@ -63,5 +63,44 @@ public override async Task Comparing_byte_column_to_enum_in_vb_creating_double_c
 FROM [Food] AS [f]
 WHERE [f].[Taste] = CAST(1 AS tinyint)");
         }
+
+        public override async Task Null_check_removal_in_ternary_maintain_appropriate_cast(bool async)
+        {
+            await base.Null_check_removal_in_ternary_maintain_appropriate_cast(async);
+
+            AssertSql(
+                @"SELECT CAST([f].[Taste] AS tinyint) AS [Bar]
+FROM [Food] AS [f]");
+        }
+
+        public override async Task Bool_discriminator_column_works(bool async)
+        {
+            await base.Bool_discriminator_column_works(async);
+
+            AssertSql(
+                @"SELECT [a].[Id], [a].[BlogId], [b].[Id], [b].[IsPhotoBlog], [b].[Title], [b].[NumberOfPhotos]
+FROM [Authors] AS [a]
+LEFT JOIN [Blog] AS [b] ON [a].[BlogId] = [b].[Id]");
+        }
+
+        public override async Task Count_member_over_IReadOnlyCollection_works(bool async)
+        {
+            await base.Count_member_over_IReadOnlyCollection_works(async);
+
+            AssertSql(
+                @"SELECT (
+    SELECT COUNT(*)
+    FROM [Books] AS [b]
+    WHERE [a].[AuthorId] = [b].[AuthorId]) AS [BooksCount]
+FROM [Authors] AS [a]");
+        }
+
+        public override async Task Multiple_different_entity_type_from_different_namespaces(bool async)
+        {
+            await base.Multiple_different_entity_type_from_different_namespaces(async);
+
+            AssertSql(
+                @"SELECT cast(null as int) AS MyValue");
+        }
     }
 }