From 2ad3a9cae33ed5cdebb42a1233a1a704e86d5399 Mon Sep 17 00:00:00 2001
From: Manish Vasani <mavasani@microsoft.com>
Date: Wed, 6 Dec 2017 12:56:04 -0800
Subject: [PATCH 1/4] Add workaround for #1318 to unblock unit tests

---
 ...ectionOnAnImmutableCollectionValueTests.cs | 433 +++++++++++++-----
 .../DiagnosticAnalyzerTestBase.cs             |   7 +-
 2 files changed, 324 insertions(+), 116 deletions(-)

diff --git a/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs b/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
index 52aa12b422..dbc0ca40c8 100644
--- a/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
+++ b/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
@@ -23,6 +23,299 @@ public class DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests : D
             nameof(ImmutableSortedDictionary)
         };
 
+        #region CSharpCollectionsDefinition
+
+        private const string CSharpCollectionsDefinition = @"
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using static System.Collections.Immutable.ImmutableExtensions;
+
+namespace System.Collections.Immutable
+{
+    public sealed partial class ImmutableArray<T> : IEnumerable<T>
+    {
+        public IEnumerator<T> GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public sealed partial class ImmutableList<T> : IEnumerable<T>
+    {
+        public IEnumerator<T> GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public sealed partial class ImmutableHashSet<T> : IEnumerable<T>
+    {
+        public IEnumerator<T> GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public sealed partial class ImmutableSortedSet<T> : IEnumerable<T>
+    {
+        public IEnumerator<T> GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public sealed partial class ImmutableDictionary<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
+    {
+        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public sealed partial class ImmutableSortedDictionary<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
+    {
+        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public static class ImmutableExtensions
+    {
+        public static ImmutableArray<T> ToImmutableArray<T>(this IEnumerable<T> source)
+        {
+            return null;
+        }
+
+        public static ImmutableArray<T> ToImmutableArray<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer)
+        {
+            return null;
+        }
+
+        public static ImmutableList<T> ToImmutableList<T>(this IEnumerable<T> source)
+        {
+            return null;
+        }
+
+        public static ImmutableList<T> ToImmutableList<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer)
+        {
+            return null;
+        }
+
+        public static ImmutableHashSet<T> ToImmutableHashSet<T>(this IEnumerable<T> source)
+        {
+            return null;
+        }
+
+        public static ImmutableHashSet<T> ToImmutableHashSet<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer)
+        {
+            return null;
+        }
+
+        public static ImmutableSortedSet<T> ToImmutableSortedSet<T>(this IEnumerable<T> source)
+        {
+            return null;
+        }
+
+        public static ImmutableSortedSet<T> ToImmutableSortedSet<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer)
+        {
+            return null;
+        }
+
+        public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source)
+        {
+            return null;
+        }
+
+        public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source, IEqualityComparer<TKey> keyComparer)
+        {
+            return null;
+        }
+
+        public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source)
+        {
+            return null;
+        }
+
+        public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source, IEqualityComparer<TKey> keyComparer)
+        {
+            return null;
+        }
+    }
+}
+";
+        private const string VisualBasicCollectionsDefinition = @"
+Imports System
+Imports System.Collections
+Imports System.Collections.Generic
+Imports System.Collections.Immutable
+Imports System.Collections.Immutable.ImmutableExtensions
+Imports System.Runtime.CompilerServices
+
+Namespace System.Collections.Immutable
+
+    Partial Public NotInheritable Class ImmutableArray(Of T)
+        Implements IEnumerable(Of T)
+
+        Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+
+        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+    End Class
+
+    Partial Public NotInheritable Class ImmutableList(Of T)
+        Implements IEnumerable(Of T)
+        Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+
+        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+    End Class
+
+    Partial Public NotInheritable Class ImmutableHashSet(Of T)
+        Implements IEnumerable(Of T)
+        Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+
+        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+    End Class
+
+    Partial Public NotInheritable Class ImmutableSortedSet(Of T)
+        Implements IEnumerable(Of T)
+        Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+
+        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+    End Class
+
+    Partial Public NotInheritable Class ImmutableDictionary(Of TKey, TValue)
+        Implements IEnumerable(Of KeyValuePair(Of TKey, TValue))
+        Public Function GetEnumerator() As IEnumerator(Of KeyValuePair(Of TKey, TValue)) Implements IEnumerable(Of KeyValuePair(Of TKey, TValue)).GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+
+        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+    End Class
+
+    Partial Public NotInheritable Class ImmutableSortedDictionary(Of TKey, TValue)
+        Implements IEnumerable(Of KeyValuePair(Of TKey, TValue))
+        Public Function GetEnumerator() As IEnumerator(Of KeyValuePair(Of TKey, TValue)) Implements IEnumerable(Of KeyValuePair(Of TKey, TValue)).GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+
+        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
+            Throw New NotImplementedException()
+        End Function
+    End Class
+
+    Module ImmutableExtensions
+        <Extension()>
+        Function ToImmutableArray(Of T)(ByVal source As IEnumerable(Of T)) As ImmutableArray(Of T)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableArray(Of T)(ByVal source As IEnumerable(Of T), ByVal comparer As IEqualityComparer(Of T)) As ImmutableArray(Of T)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableList(Of T)(ByVal source As IEnumerable(Of T)) As ImmutableList(Of T)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableList(Of T)(ByVal source As IEnumerable(Of T), ByVal comparer As IEqualityComparer(Of T)) As ImmutableList(Of T)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableHashSet(Of T)(ByVal source As IEnumerable(Of T)) As ImmutableHashSet(Of T)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableHashSet(Of T)(ByVal source As IEnumerable(Of T), ByVal comparer As IEqualityComparer(Of T)) As ImmutableHashSet(Of T)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableSortedSet(Of T)(ByVal source As IEnumerable(Of T)) As ImmutableSortedSet(Of T)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableSortedSet(Of T)(ByVal source As IEnumerable(Of T), ByVal comparer As IEqualityComparer(Of T)) As ImmutableSortedSet(Of T)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableDictionary(Of TKey, TValue)(ByVal source As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As ImmutableDictionary(Of TKey, TValue)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableDictionary(Of TKey, TValue)(ByVal source As IEnumerable(Of KeyValuePair(Of TKey, TValue)), ByVal keyComparer As IEqualityComparer(Of TKey)) As ImmutableDictionary(Of TKey, TValue)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableSortedDictionary(Of TKey, TValue)(ByVal source As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As ImmutableSortedDictionary(Of TKey, TValue)
+            Return Nothing
+        End Function
+
+        <Extension()>
+        Function ToImmutableSortedDictionary(Of TKey, TValue)(ByVal source As IEnumerable(Of KeyValuePair(Of TKey, TValue)), ByVal keyComparer As IEqualityComparer(Of TKey)) As ImmutableSortedDictionary(Of TKey, TValue)
+            Return Nothing
+        End Function
+    End Module
+End Namespace
+";
+        #endregion
+
         protected override DiagnosticAnalyzer GetBasicDiagnosticAnalyzer()
         {
             return new DoNotCallToImmutableCollectionOnAnImmutableCollectionValueAnalyzer();
@@ -39,19 +332,7 @@ protected override DiagnosticAnalyzer GetCSharpDiagnosticAnalyzer()
         [MemberData(nameof(CollectionNames_Arity1))]
         public void NoDiagnosticCases_Arity1(string collectionName)
         {
-            VerifyCSharp($@"
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using static System.Collections.Immutable.{collectionName};
-
-static class Extensions
-{{
-     public static {collectionName}<TSource> To{collectionName}<TSource>(this IEnumerable<TSource> items)
-     {{
-         return default({collectionName}<TSource>);
-     }}
-}}
-
+            VerifyCSharp(CSharpCollectionsDefinition + $@"
 class C
 {{
     public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3)
@@ -67,17 +348,7 @@ public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3)
 }}
 ");
 
-            VerifyBasic($@"
-Imports System.Collections.Generic
-Imports System.Collections.Immutable
-
-Module Extensions
-	<System.Runtime.CompilerServices.Extension> _
-	Public Function To{collectionName}(Of TSource)(items As IEnumerable(Of TSource)) As {collectionName}(Of TSource)
-		Return Nothing
-	End Function
-End Module
-
+            VerifyBasic(VisualBasicCollectionsDefinition + $@"
 Class C
 	Public Sub M(p1 As IEnumerable(Of Integer), p2 As List(Of Integer), p3 As {collectionName}(Of Integer))
 		' Allowed
@@ -96,19 +367,7 @@ End Class
         [MemberData(nameof(CollectionNames_Arity2))]
         public void NoDiagnosticCases_Arity2(string collectionName)
         {
-            VerifyCSharp($@"
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using static System.Collections.Immutable.{collectionName};
-
-static class Extensions
-{{
-     public static {collectionName}<TKey, TValue> To{collectionName}<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> items)
-     {{
-         return default({collectionName}<TKey, TValue>);
-     }}
-}}
-
+            VerifyCSharp(CSharpCollectionsDefinition + $@"
 class C
 {{
     public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int>> p2, {collectionName}<int, int> p3)
@@ -124,17 +383,7 @@ public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int
 }}
 ");
 
-            VerifyBasic($@"
-Imports System.Collections.Generic
-Imports System.Collections.Immutable
-
-Module Extensions
-	<System.Runtime.CompilerServices.Extension> _
-	Public Function To{collectionName}(Of TKey, TValue)(items As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As {collectionName}(Of TKey, TValue)
-		Return Nothing
-	End Function
-End Module
-
+            VerifyBasic(VisualBasicCollectionsDefinition + $@"
 Class C
 	Public Sub M(p1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)), p2 As List(Of KeyValuePair(Of Integer, Integer)), p3 As {collectionName}(Of Integer, Integer))
 		' Allowed
@@ -153,23 +402,11 @@ End Class
 
         #region Diagnostic Tests
 
-        [Theory(Skip = "https://github.com/dotnet/roslyn-analyzers/issues/1318")]
+        [Theory]
         [MemberData(nameof(CollectionNames_Arity1))]
         public void DiagnosticCases_Arity1(string collectionName)
         {
-            VerifyCSharp($@"
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using static System.Collections.Immutable.{collectionName};
-
-static class Extensions
-{{
-     public static {collectionName}<TSource> To{collectionName}<TSource>(this IEnumerable<TSource> items)
-     {{
-         return default({collectionName}<TSource>);
-     }}
-}}
-
+            VerifyCSharp(CSharpCollectionsDefinition + $@"
 class C
 {{
     public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3)
@@ -179,22 +416,12 @@ public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3)
     }}
 }}
 ",
-    // Test0.cs(18,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetCSharpResultAt(18, 9, collectionName),
-    // Test0.cs(19,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetCSharpResultAt(19, 9, collectionName));
-
-            VerifyBasic($@"
-Imports System.Collections.Generic
-Imports System.Collections.Immutable
-
-Module Extensions
-	<System.Runtime.CompilerServices.Extension> _
-	Public Function To{collectionName}(Of TSource)(items As IEnumerable(Of TSource)) As {collectionName}(Of TSource)
-		Return Nothing
-	End Function
-End Module
+    // Test0.cs(154,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetCSharpResultAt(154, 9, collectionName),
+    // Test0.cs(155,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetCSharpResultAt(155, 9, collectionName));
 
+            VerifyBasic(VisualBasicCollectionsDefinition + $@"
 Class C
 	Public Sub M(p1 As IEnumerable(Of Integer), p2 As List(Of Integer), p3 As {collectionName}(Of Integer))
 		p1.To{collectionName}().To{collectionName}()
@@ -202,29 +429,17 @@ Public Sub M(p1 As IEnumerable(Of Integer), p2 As List(Of Integer), p3 As {colle
 	End Sub
 End Class
 ",
-    // Test0.vb(14,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetBasicResultAt(14, 3, collectionName),
-    // Test0.vb(15,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetBasicResultAt(15, 3, collectionName));
+    // Test0.vb(143,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetBasicResultAt(143, 3, collectionName),
+    // Test0.vb(144,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetBasicResultAt(144, 3, collectionName));
         }
 
-        [Theory(Skip = "https://github.com/dotnet/roslyn-analyzers/issues/1318")]
+        [Theory]
         [MemberData(nameof(CollectionNames_Arity2))]
         public void DiagnosticCases_Arity2(string collectionName)
         {
-            VerifyCSharp($@"
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using static System.Collections.Immutable.{collectionName};
-
-static class Extensions
-{{
-     public static {collectionName}<TKey, TValue> To{collectionName}<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> items)
-     {{
-         return default({collectionName}<TKey, TValue>);
-     }}
-}}
-
+            VerifyCSharp(CSharpCollectionsDefinition + $@"
 class C
 {{
     public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int>> p2, {collectionName}<int, int> p3)
@@ -234,22 +449,12 @@ public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int
     }}
 }}
 ",
-    // Test0.cs(18,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetCSharpResultAt(18, 9, collectionName),
-    // Test0.cs(19,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetCSharpResultAt(19, 9, collectionName));
-
-            VerifyBasic($@"
-Imports System.Collections.Generic
-Imports System.Collections.Immutable
-
-Module Extensions
-	<System.Runtime.CompilerServices.Extension> _
-	Public Function To{collectionName}(Of TKey, TValue)(items As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As {collectionName}(Of TKey, TValue)
-		Return Nothing
-	End Function
-End Module
+    // Test0.cs(154,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetCSharpResultAt(154, 9, collectionName),
+    // Test0.cs(155,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetCSharpResultAt(155, 9, collectionName));
 
+            VerifyBasic(VisualBasicCollectionsDefinition + $@"
 Class C
 	Public Sub M(p1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)), p2 As List(Of KeyValuePair(Of Integer, Integer)), p3 As {collectionName}(Of Integer, Integer))
 		p1.To{collectionName}().To{collectionName}()
@@ -257,10 +462,10 @@ Public Sub M(p1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)), p2 As List
 	End Sub
 End Class
 ",
-    // Test0.vb(14,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetBasicResultAt(14, 3, collectionName),
-    // Test0.vb(15,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetBasicResultAt(15, 3, collectionName));
+    // Test0.vb(143,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetBasicResultAt(143, 3, collectionName),
+    // Test0.vb(144,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetBasicResultAt(144, 3, collectionName));
         }
 
         #endregion
diff --git a/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs b/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
index 302aab67ae..22917a48be 100644
--- a/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
+++ b/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
@@ -28,13 +28,16 @@ public abstract class DiagnosticAnalyzerTestBase
         private static readonly MetadataReference s_visualBasicReference = MetadataReference.CreateFromFile(typeof(Microsoft.VisualBasic.Devices.ComputerInfo).Assembly.Location);
         private static readonly MetadataReference s_codeAnalysisReference = MetadataReference.CreateFromFile(typeof(Compilation).Assembly.Location);
         private static readonly MetadataReference s_workspacesReference = MetadataReference.CreateFromFile(typeof(Workspace).Assembly.Location);
-        private static readonly MetadataReference s_immutableCollectionsReference = MetadataReference.CreateFromFile(typeof(ImmutableArray<int>).Assembly.Location);
         private static readonly MetadataReference s_systemDiagnosticsDebugReference = MetadataReference.CreateFromFile(typeof(Debug).Assembly.Location);
         private static readonly MetadataReference s_systemDataReference = MetadataReference.CreateFromFile(typeof(System.Data.DataSet).Assembly.Location);
         protected static readonly CompilationOptions s_CSharpDefaultOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
         protected static readonly CompilationOptions s_CSharpUnsafeCodeDefaultOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary).WithAllowUnsafe(true);
         protected static readonly CompilationOptions s_visualBasicDefaultOptions = new VisualBasicCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
 
+#pragma warning disable CA1823 // Avoid unused private fields https://github.com/dotnet/roslyn-analyzers/issues/1318
+        private static readonly MetadataReference s_immutableCollectionsReference = MetadataReference.CreateFromFile(typeof(ImmutableArray<int>).Assembly.Location);
+#pragma warning restore CA1823 // Avoid unused private fields
+
         internal const string DefaultFilePathPrefix = "Test";
         internal const string CSharpDefaultFileExt = "cs";
         internal const string VisualBasicDefaultExt = "vb";
@@ -372,7 +375,7 @@ private static Project CreateProject(
                 .AddMetadataReference(projectId, SystemRuntimeFacadeRef)
                 .AddMetadataReference(projectId, SystemThreadingFacadeRef)
                 .AddMetadataReference(projectId, SystemThreadingTaskFacadeRef)
-                .AddMetadataReference(projectId, s_immutableCollectionsReference)
+                //.AddMetadataReference(projectId, s_immutableCollectionsReference) https://github.com/dotnet/roslyn-analyzers/issues/1318
                 .AddMetadataReference(projectId, s_workspacesReference)
                 .AddMetadataReference(projectId, s_systemDiagnosticsDebugReference)
                 .AddMetadataReference(projectId, s_systemDataReference)

From 5bd1b458584f1e08dbdfeee6b9196ab20e7e78f2 Mon Sep 17 00:00:00 2001
From: Manish Vasani <mavasani@microsoft.com>
Date: Wed, 6 Dec 2017 14:01:17 -0800
Subject: [PATCH 2/4] Do not flag RS0012 for ToImmutable invocations if the
 contents of the underlying collection could be modified by the invoked API.

Fixes #1430
---
 ...eCollectionOnAnImmutableCollectionValue.cs | 11 ++++++++++
 ...ectionOnAnImmutableCollectionValueTests.cs | 20 +++++++++++++------
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/src/Microsoft.NetCore.Analyzers/Core/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValue.cs b/src/Microsoft.NetCore.Analyzers/Core/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValue.cs
index 6ee1dd7a97..cffd08a91a 100644
--- a/src/Microsoft.NetCore.Analyzers/Core/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValue.cs
+++ b/src/Microsoft.NetCore.Analyzers/Core/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValue.cs
@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
+using System.Linq;
 using Analyzer.Utilities;
 using Analyzer.Utilities.Extensions;
 using Microsoft.CodeAnalysis;
@@ -67,6 +68,16 @@ public override void Initialize(AnalysisContext context)
                     }
 
                     Debug.Assert(!string.IsNullOrEmpty(metadataName));
+
+                    // Do not flag invocations that take any explicit argument (comparer, converter, etc.)
+                    // as they can potentially modify the contents of the resulting collection.
+                    // See https://github.com/dotnet/roslyn/issues/23625 for language specific implementation below.
+                    var argumentsToSkip = targetMethod.IsExtensionMethod && invocation.Language != LanguageNames.VisualBasic ? 1 : 0;
+                    if (invocation.Arguments.Skip(argumentsToSkip).Any(arg => arg.ArgumentKind == ArgumentKind.Explicit))
+                    {
+                        return;
+                    }
+
                     var immutableCollectionType = compilation.GetTypeByMetadataName(metadataName);
                     if (immutableCollectionType == null)
                     {
diff --git a/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs b/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
index dbc0ca40c8..f33635f605 100644
--- a/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
+++ b/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
@@ -174,6 +174,10 @@ public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionar
     }
 }
 ";
+        #endregion
+
+        #region VisualBasicCollectionsDefinition
+
         private const string VisualBasicCollectionsDefinition = @"
 Imports System
 Imports System.Collections
@@ -328,18 +332,19 @@ protected override DiagnosticAnalyzer GetCSharpDiagnosticAnalyzer()
 
         #region No Diagnostic Tests
 
-        [Theory]
+        [Theory, WorkItem(1432, "https://github.com/dotnet/roslyn-analyzers/issues/1432")]
         [MemberData(nameof(CollectionNames_Arity1))]
         public void NoDiagnosticCases_Arity1(string collectionName)
         {
             VerifyCSharp(CSharpCollectionsDefinition + $@"
 class C
 {{
-    public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3)
+    public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3, IEqualityComparer<int> comparer)
     {{
         // Allowed
         p1.To{collectionName}();
         p2.To{collectionName}();
+        p3.To{collectionName}(comparer); // Potentially modifies the collection
 
         // No dataflow
         IEnumerable<int> l1 = p3;
@@ -350,10 +355,11 @@ public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3)
 
             VerifyBasic(VisualBasicCollectionsDefinition + $@"
 Class C
-	Public Sub M(p1 As IEnumerable(Of Integer), p2 As List(Of Integer), p3 As {collectionName}(Of Integer))
+	Public Sub M(p1 As IEnumerable(Of Integer), p2 As List(Of Integer), p3 As {collectionName}(Of Integer), comparer As IEqualityComparer(Of Integer))
 		' Allowed
 		p1.To{collectionName}()
 		p2.To{collectionName}()
+        p3.To{collectionName}(comparer) ' Potentially modifies the collection
 
 		' No dataflow
 		Dim l1 As IEnumerable(Of Integer) = p3
@@ -363,18 +369,19 @@ End Class
 ");
         }
 
-        [Theory]
+        [Theory, WorkItem(1432, "https://github.com/dotnet/roslyn-analyzers/issues/1432")]
         [MemberData(nameof(CollectionNames_Arity2))]
         public void NoDiagnosticCases_Arity2(string collectionName)
         {
             VerifyCSharp(CSharpCollectionsDefinition + $@"
 class C
 {{
-    public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int>> p2, {collectionName}<int, int> p3)
+    public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int>> p2, {collectionName}<int, int> p3, IEqualityComparer<int> keyComparer)
     {{
         // Allowed
         p1.To{collectionName}();
         p2.To{collectionName}();
+        p3.To{collectionName}(keyComparer); // Potentially modifies the collection
 
         // No dataflow
         IEnumerable<KeyValuePair<int, int>> l1 = p3;
@@ -385,10 +392,11 @@ public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int
 
             VerifyBasic(VisualBasicCollectionsDefinition + $@"
 Class C
-	Public Sub M(p1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)), p2 As List(Of KeyValuePair(Of Integer, Integer)), p3 As {collectionName}(Of Integer, Integer))
+	Public Sub M(p1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)), p2 As List(Of KeyValuePair(Of Integer, Integer)), p3 As {collectionName}(Of Integer, Integer), keyComparer As IEqualityComparer(Of Integer))
 		' Allowed
 		p1.To{collectionName}()
 		p2.To{collectionName}()
+        p3.To{collectionName}(keyComparer) ' Potentially modifies the collection
 
 		' No dataflow
 		Dim l1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)) = p3

From 5817c2f967525a46c85bd4aeab7ff000344a91b4 Mon Sep 17 00:00:00 2001
From: Manish Vasani <mavasani@microsoft.com>
Date: Wed, 6 Dec 2017 14:57:38 -0800
Subject: [PATCH 3/4] Revert the change to comment out
 SystemCollectionsImmutable reference as large number of tests depend on it

---
 ...ectionOnAnImmutableCollectionValueTests.cs | 453 +++++-------------
 ...crosoft.NetCore.Analyzers.UnitTests.csproj |   3 +
 .../DiagnosticAnalyzerTestBase.cs             |   7 +-
 3 files changed, 137 insertions(+), 326 deletions(-)

diff --git a/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs b/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
index f33635f605..d931108965 100644
--- a/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
+++ b/src/Microsoft.NetCore.Analyzers/UnitTests/ImmutableCollections/DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests.cs
@@ -23,303 +23,6 @@ public class DoNotCallToImmutableCollectionOnAnImmutableCollectionValueTests : D
             nameof(ImmutableSortedDictionary)
         };
 
-        #region CSharpCollectionsDefinition
-
-        private const string CSharpCollectionsDefinition = @"
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using static System.Collections.Immutable.ImmutableExtensions;
-
-namespace System.Collections.Immutable
-{
-    public sealed partial class ImmutableArray<T> : IEnumerable<T>
-    {
-        public IEnumerator<T> GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-    }
-
-    public sealed partial class ImmutableList<T> : IEnumerable<T>
-    {
-        public IEnumerator<T> GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-    }
-
-    public sealed partial class ImmutableHashSet<T> : IEnumerable<T>
-    {
-        public IEnumerator<T> GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-    }
-
-    public sealed partial class ImmutableSortedSet<T> : IEnumerable<T>
-    {
-        public IEnumerator<T> GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-    }
-
-    public sealed partial class ImmutableDictionary<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
-    {
-        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-    }
-
-    public sealed partial class ImmutableSortedDictionary<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
-    {
-        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            throw new NotImplementedException();
-        }
-    }
-
-    public static class ImmutableExtensions
-    {
-        public static ImmutableArray<T> ToImmutableArray<T>(this IEnumerable<T> source)
-        {
-            return null;
-        }
-
-        public static ImmutableArray<T> ToImmutableArray<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer)
-        {
-            return null;
-        }
-
-        public static ImmutableList<T> ToImmutableList<T>(this IEnumerable<T> source)
-        {
-            return null;
-        }
-
-        public static ImmutableList<T> ToImmutableList<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer)
-        {
-            return null;
-        }
-
-        public static ImmutableHashSet<T> ToImmutableHashSet<T>(this IEnumerable<T> source)
-        {
-            return null;
-        }
-
-        public static ImmutableHashSet<T> ToImmutableHashSet<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer)
-        {
-            return null;
-        }
-
-        public static ImmutableSortedSet<T> ToImmutableSortedSet<T>(this IEnumerable<T> source)
-        {
-            return null;
-        }
-
-        public static ImmutableSortedSet<T> ToImmutableSortedSet<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer)
-        {
-            return null;
-        }
-
-        public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source)
-        {
-            return null;
-        }
-
-        public static ImmutableDictionary<TKey, TValue> ToImmutableDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source, IEqualityComparer<TKey> keyComparer)
-        {
-            return null;
-        }
-
-        public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source)
-        {
-            return null;
-        }
-
-        public static ImmutableSortedDictionary<TKey, TValue> ToImmutableSortedDictionary<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> source, IEqualityComparer<TKey> keyComparer)
-        {
-            return null;
-        }
-    }
-}
-";
-        #endregion
-
-        #region VisualBasicCollectionsDefinition
-
-        private const string VisualBasicCollectionsDefinition = @"
-Imports System
-Imports System.Collections
-Imports System.Collections.Generic
-Imports System.Collections.Immutable
-Imports System.Collections.Immutable.ImmutableExtensions
-Imports System.Runtime.CompilerServices
-
-Namespace System.Collections.Immutable
-
-    Partial Public NotInheritable Class ImmutableArray(Of T)
-        Implements IEnumerable(Of T)
-
-        Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-
-        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-    End Class
-
-    Partial Public NotInheritable Class ImmutableList(Of T)
-        Implements IEnumerable(Of T)
-        Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-
-        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-    End Class
-
-    Partial Public NotInheritable Class ImmutableHashSet(Of T)
-        Implements IEnumerable(Of T)
-        Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-
-        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-    End Class
-
-    Partial Public NotInheritable Class ImmutableSortedSet(Of T)
-        Implements IEnumerable(Of T)
-        Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-
-        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-    End Class
-
-    Partial Public NotInheritable Class ImmutableDictionary(Of TKey, TValue)
-        Implements IEnumerable(Of KeyValuePair(Of TKey, TValue))
-        Public Function GetEnumerator() As IEnumerator(Of KeyValuePair(Of TKey, TValue)) Implements IEnumerable(Of KeyValuePair(Of TKey, TValue)).GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-
-        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-    End Class
-
-    Partial Public NotInheritable Class ImmutableSortedDictionary(Of TKey, TValue)
-        Implements IEnumerable(Of KeyValuePair(Of TKey, TValue))
-        Public Function GetEnumerator() As IEnumerator(Of KeyValuePair(Of TKey, TValue)) Implements IEnumerable(Of KeyValuePair(Of TKey, TValue)).GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-
-        Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
-            Throw New NotImplementedException()
-        End Function
-    End Class
-
-    Module ImmutableExtensions
-        <Extension()>
-        Function ToImmutableArray(Of T)(ByVal source As IEnumerable(Of T)) As ImmutableArray(Of T)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableArray(Of T)(ByVal source As IEnumerable(Of T), ByVal comparer As IEqualityComparer(Of T)) As ImmutableArray(Of T)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableList(Of T)(ByVal source As IEnumerable(Of T)) As ImmutableList(Of T)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableList(Of T)(ByVal source As IEnumerable(Of T), ByVal comparer As IEqualityComparer(Of T)) As ImmutableList(Of T)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableHashSet(Of T)(ByVal source As IEnumerable(Of T)) As ImmutableHashSet(Of T)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableHashSet(Of T)(ByVal source As IEnumerable(Of T), ByVal comparer As IEqualityComparer(Of T)) As ImmutableHashSet(Of T)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableSortedSet(Of T)(ByVal source As IEnumerable(Of T)) As ImmutableSortedSet(Of T)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableSortedSet(Of T)(ByVal source As IEnumerable(Of T), ByVal comparer As IEqualityComparer(Of T)) As ImmutableSortedSet(Of T)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableDictionary(Of TKey, TValue)(ByVal source As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As ImmutableDictionary(Of TKey, TValue)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableDictionary(Of TKey, TValue)(ByVal source As IEnumerable(Of KeyValuePair(Of TKey, TValue)), ByVal keyComparer As IEqualityComparer(Of TKey)) As ImmutableDictionary(Of TKey, TValue)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableSortedDictionary(Of TKey, TValue)(ByVal source As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As ImmutableSortedDictionary(Of TKey, TValue)
-            Return Nothing
-        End Function
-
-        <Extension()>
-        Function ToImmutableSortedDictionary(Of TKey, TValue)(ByVal source As IEnumerable(Of KeyValuePair(Of TKey, TValue)), ByVal keyComparer As IEqualityComparer(Of TKey)) As ImmutableSortedDictionary(Of TKey, TValue)
-            Return Nothing
-        End Function
-    End Module
-End Namespace
-";
-        #endregion
-
         protected override DiagnosticAnalyzer GetBasicDiagnosticAnalyzer()
         {
             return new DoNotCallToImmutableCollectionOnAnImmutableCollectionValueAnalyzer();
@@ -336,7 +39,24 @@ protected override DiagnosticAnalyzer GetCSharpDiagnosticAnalyzer()
         [MemberData(nameof(CollectionNames_Arity1))]
         public void NoDiagnosticCases_Arity1(string collectionName)
         {
-            VerifyCSharp(CSharpCollectionsDefinition + $@"
+            VerifyCSharp($@"
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using static System.Collections.Immutable.{collectionName};
+
+static class Extensions
+{{
+     public static {collectionName}<TSource> To{collectionName}<TSource>(this IEnumerable<TSource> items)
+     {{
+         return default({collectionName}<TSource>);
+     }}
+
+     public static {collectionName}<TSource> To{collectionName}<TSource>(this IEnumerable<TSource> items, IEqualityComparer<TSource> comparer)
+     {{
+         return default({collectionName}<TSource>);
+     }}
+}}
+
 class C
 {{
     public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3, IEqualityComparer<int> comparer)
@@ -353,7 +73,22 @@ public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3, IEqua
 }}
 ");
 
-            VerifyBasic(VisualBasicCollectionsDefinition + $@"
+            VerifyBasic($@"
+Imports System.Collections.Generic
+Imports System.Collections.Immutable
+
+Module Extensions
+	<System.Runtime.CompilerServices.Extension> _
+	Public Function To{collectionName}(Of TSource)(items As IEnumerable(Of TSource)) As {collectionName}(Of TSource)
+		Return Nothing
+	End Function
+
+	<System.Runtime.CompilerServices.Extension> _
+	Public Function To{collectionName}(Of TSource)(items As IEnumerable(Of TSource), comparer as IEqualityComparer(Of TSource)) As {collectionName}(Of TSource)
+		Return Nothing
+	End Function
+End Module
+
 Class C
 	Public Sub M(p1 As IEnumerable(Of Integer), p2 As List(Of Integer), p3 As {collectionName}(Of Integer), comparer As IEqualityComparer(Of Integer))
 		' Allowed
@@ -373,7 +108,24 @@ End Class
         [MemberData(nameof(CollectionNames_Arity2))]
         public void NoDiagnosticCases_Arity2(string collectionName)
         {
-            VerifyCSharp(CSharpCollectionsDefinition + $@"
+            VerifyCSharp($@"
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using static System.Collections.Immutable.{collectionName};
+
+static class Extensions
+{{
+     public static {collectionName}<TKey, TValue> To{collectionName}<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> items)
+     {{
+         return default({collectionName}<TKey, TValue>);
+     }}
+
+    public static {collectionName}<TKey, TValue> To{collectionName}<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> items, IEqualityComparer<TKey> keyComparer)
+     {{
+         return default({collectionName}<TKey, TValue>);
+     }}
+}}
+
 class C
 {{
     public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int>> p2, {collectionName}<int, int> p3, IEqualityComparer<int> keyComparer)
@@ -390,7 +142,22 @@ public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int
 }}
 ");
 
-            VerifyBasic(VisualBasicCollectionsDefinition + $@"
+            VerifyBasic($@"
+Imports System.Collections.Generic
+Imports System.Collections.Immutable
+
+Module Extensions
+	<System.Runtime.CompilerServices.Extension> _
+	Public Function To{collectionName}(Of TKey, TValue)(items As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As {collectionName}(Of TKey, TValue)
+		Return Nothing
+	End Function
+
+	<System.Runtime.CompilerServices.Extension> _
+	Public Function To{collectionName}(Of TKey, TValue)(items As IEnumerable(Of KeyValuePair(Of TKey, TValue)), keyComparer As IEqualityComparer(Of TKey)) As {collectionName}(Of TKey, TValue)
+		Return Nothing
+	End Function
+End Module
+
 Class C
 	Public Sub M(p1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)), p2 As List(Of KeyValuePair(Of Integer, Integer)), p3 As {collectionName}(Of Integer, Integer), keyComparer As IEqualityComparer(Of Integer))
 		' Allowed
@@ -414,7 +181,19 @@ End Class
         [MemberData(nameof(CollectionNames_Arity1))]
         public void DiagnosticCases_Arity1(string collectionName)
         {
-            VerifyCSharp(CSharpCollectionsDefinition + $@"
+            VerifyCSharp($@"
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using static System.Collections.Immutable.{collectionName};
+
+static class Extensions
+{{
+     public static {collectionName}<TSource> To{collectionName}<TSource>(this IEnumerable<TSource> items)
+     {{
+         return default({collectionName}<TSource>);
+     }}
+}}
+
 class C
 {{
     public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3)
@@ -424,12 +203,22 @@ public void M(IEnumerable<int> p1, List<int> p2, {collectionName}<int> p3)
     }}
 }}
 ",
-    // Test0.cs(154,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetCSharpResultAt(154, 9, collectionName),
-    // Test0.cs(155,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetCSharpResultAt(155, 9, collectionName));
+    // Test0.cs(18,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetCSharpResultAt(18, 9, collectionName),
+    // Test0.cs(19,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetCSharpResultAt(19, 9, collectionName));
+
+            VerifyBasic($@"
+Imports System.Collections.Generic
+Imports System.Collections.Immutable
+
+Module Extensions
+	<System.Runtime.CompilerServices.Extension> _
+	Public Function To{collectionName}(Of TSource)(items As IEnumerable(Of TSource)) As {collectionName}(Of TSource)
+		Return Nothing
+	End Function
+End Module
 
-            VerifyBasic(VisualBasicCollectionsDefinition + $@"
 Class C
 	Public Sub M(p1 As IEnumerable(Of Integer), p2 As List(Of Integer), p3 As {collectionName}(Of Integer))
 		p1.To{collectionName}().To{collectionName}()
@@ -437,17 +226,29 @@ Public Sub M(p1 As IEnumerable(Of Integer), p2 As List(Of Integer), p3 As {colle
 	End Sub
 End Class
 ",
-    // Test0.vb(143,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetBasicResultAt(143, 3, collectionName),
-    // Test0.vb(144,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetBasicResultAt(144, 3, collectionName));
+    // Test0.vb(14,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetBasicResultAt(14, 3, collectionName),
+    // Test0.vb(15,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetBasicResultAt(15, 3, collectionName));
         }
 
         [Theory]
         [MemberData(nameof(CollectionNames_Arity2))]
         public void DiagnosticCases_Arity2(string collectionName)
         {
-            VerifyCSharp(CSharpCollectionsDefinition + $@"
+            VerifyCSharp($@"
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using static System.Collections.Immutable.{collectionName};
+
+static class Extensions
+{{
+     public static {collectionName}<TKey, TValue> To{collectionName}<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> items)
+     {{
+         return default({collectionName}<TKey, TValue>);
+     }}
+}}
+
 class C
 {{
     public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int>> p2, {collectionName}<int, int> p3)
@@ -457,12 +258,22 @@ public void M(IEnumerable<KeyValuePair<int, int>> p1, List<KeyValuePair<int, int
     }}
 }}
 ",
-    // Test0.cs(154,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetCSharpResultAt(154, 9, collectionName),
-    // Test0.cs(155,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetCSharpResultAt(155, 9, collectionName));
+    // Test0.cs(18,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetCSharpResultAt(18, 9, collectionName),
+    // Test0.cs(19,9): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetCSharpResultAt(19, 9, collectionName));
+
+            VerifyBasic($@"
+Imports System.Collections.Generic
+Imports System.Collections.Immutable
+
+Module Extensions
+	<System.Runtime.CompilerServices.Extension> _
+	Public Function To{collectionName}(Of TKey, TValue)(items As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As {collectionName}(Of TKey, TValue)
+		Return Nothing
+	End Function
+End Module
 
-            VerifyBasic(VisualBasicCollectionsDefinition + $@"
 Class C
 	Public Sub M(p1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)), p2 As List(Of KeyValuePair(Of Integer, Integer)), p3 As {collectionName}(Of Integer, Integer))
 		p1.To{collectionName}().To{collectionName}()
@@ -470,10 +281,10 @@ Public Sub M(p1 As IEnumerable(Of KeyValuePair(Of Integer, Integer)), p2 As List
 	End Sub
 End Class
 ",
-    // Test0.vb(143,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetBasicResultAt(143, 3, collectionName),
-    // Test0.vb(144,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
-    GetBasicResultAt(144, 3, collectionName));
+    // Test0.vb(14,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetBasicResultAt(14, 3, collectionName),
+    // Test0.vb(15,3): warning RS0012: Do not call ToImmutableCollection on an ImmutableCollection value
+    GetBasicResultAt(15, 3, collectionName));
         }
 
         #endregion
diff --git a/src/Microsoft.NetCore.Analyzers/UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj b/src/Microsoft.NetCore.Analyzers/UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj
index c2bfc9ee24..b04cfeb279 100644
--- a/src/Microsoft.NetCore.Analyzers/UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj
+++ b/src/Microsoft.NetCore.Analyzers/UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj
@@ -9,4 +9,7 @@
     <ProjectReference Include="..\CSharp\Microsoft.NetCore.CSharp.Analyzers.csproj" />
     <ProjectReference Include="..\VisualBasic\Microsoft.NetCore.VisualBasic.Analyzers.vbproj" />
   </ItemGroup>
+  <ItemGroup>
+    <Folder Include="Composition\" />
+  </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs b/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
index 22917a48be..e8d01f62eb 100644
--- a/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
+++ b/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
@@ -29,15 +29,12 @@ public abstract class DiagnosticAnalyzerTestBase
         private static readonly MetadataReference s_codeAnalysisReference = MetadataReference.CreateFromFile(typeof(Compilation).Assembly.Location);
         private static readonly MetadataReference s_workspacesReference = MetadataReference.CreateFromFile(typeof(Workspace).Assembly.Location);
         private static readonly MetadataReference s_systemDiagnosticsDebugReference = MetadataReference.CreateFromFile(typeof(Debug).Assembly.Location);
+        private static readonly MetadataReference s_immutableCollectionsReference = MetadataReference.CreateFromFile(typeof(ImmutableArray<int>).Assembly.Location);
         private static readonly MetadataReference s_systemDataReference = MetadataReference.CreateFromFile(typeof(System.Data.DataSet).Assembly.Location);
         protected static readonly CompilationOptions s_CSharpDefaultOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
         protected static readonly CompilationOptions s_CSharpUnsafeCodeDefaultOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary).WithAllowUnsafe(true);
         protected static readonly CompilationOptions s_visualBasicDefaultOptions = new VisualBasicCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
 
-#pragma warning disable CA1823 // Avoid unused private fields https://github.com/dotnet/roslyn-analyzers/issues/1318
-        private static readonly MetadataReference s_immutableCollectionsReference = MetadataReference.CreateFromFile(typeof(ImmutableArray<int>).Assembly.Location);
-#pragma warning restore CA1823 // Avoid unused private fields
-
         internal const string DefaultFilePathPrefix = "Test";
         internal const string CSharpDefaultFileExt = "cs";
         internal const string VisualBasicDefaultExt = "vb";
@@ -375,7 +372,7 @@ private static Project CreateProject(
                 .AddMetadataReference(projectId, SystemRuntimeFacadeRef)
                 .AddMetadataReference(projectId, SystemThreadingFacadeRef)
                 .AddMetadataReference(projectId, SystemThreadingTaskFacadeRef)
-                //.AddMetadataReference(projectId, s_immutableCollectionsReference) https://github.com/dotnet/roslyn-analyzers/issues/1318
+                .AddMetadataReference(projectId, s_immutableCollectionsReference)
                 .AddMetadataReference(projectId, s_workspacesReference)
                 .AddMetadataReference(projectId, s_systemDiagnosticsDebugReference)
                 .AddMetadataReference(projectId, s_systemDataReference)

From b71a93e2de79bd4b7ed5d3573d99efbedcdde870 Mon Sep 17 00:00:00 2001
From: Manish Vasani <mavasani@microsoft.com>
Date: Wed, 6 Dec 2017 14:59:26 -0800
Subject: [PATCH 4/4] Remove couple of accidental unncessary changes

---
 .../UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj     | 3 ---
 src/Test.Utilities/DiagnosticAnalyzerTestBase.cs               | 2 +-
 2 files changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/Microsoft.NetCore.Analyzers/UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj b/src/Microsoft.NetCore.Analyzers/UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj
index b04cfeb279..c2bfc9ee24 100644
--- a/src/Microsoft.NetCore.Analyzers/UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj
+++ b/src/Microsoft.NetCore.Analyzers/UnitTests/Microsoft.NetCore.Analyzers.UnitTests.csproj
@@ -9,7 +9,4 @@
     <ProjectReference Include="..\CSharp\Microsoft.NetCore.CSharp.Analyzers.csproj" />
     <ProjectReference Include="..\VisualBasic\Microsoft.NetCore.VisualBasic.Analyzers.vbproj" />
   </ItemGroup>
-  <ItemGroup>
-    <Folder Include="Composition\" />
-  </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs b/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
index e8d01f62eb..302aab67ae 100644
--- a/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
+++ b/src/Test.Utilities/DiagnosticAnalyzerTestBase.cs
@@ -28,8 +28,8 @@ public abstract class DiagnosticAnalyzerTestBase
         private static readonly MetadataReference s_visualBasicReference = MetadataReference.CreateFromFile(typeof(Microsoft.VisualBasic.Devices.ComputerInfo).Assembly.Location);
         private static readonly MetadataReference s_codeAnalysisReference = MetadataReference.CreateFromFile(typeof(Compilation).Assembly.Location);
         private static readonly MetadataReference s_workspacesReference = MetadataReference.CreateFromFile(typeof(Workspace).Assembly.Location);
-        private static readonly MetadataReference s_systemDiagnosticsDebugReference = MetadataReference.CreateFromFile(typeof(Debug).Assembly.Location);
         private static readonly MetadataReference s_immutableCollectionsReference = MetadataReference.CreateFromFile(typeof(ImmutableArray<int>).Assembly.Location);
+        private static readonly MetadataReference s_systemDiagnosticsDebugReference = MetadataReference.CreateFromFile(typeof(Debug).Assembly.Location);
         private static readonly MetadataReference s_systemDataReference = MetadataReference.CreateFromFile(typeof(System.Data.DataSet).Assembly.Location);
         protected static readonly CompilationOptions s_CSharpDefaultOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
         protected static readonly CompilationOptions s_CSharpUnsafeCodeDefaultOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary).WithAllowUnsafe(true);