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stephentoubstephentoub
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Add ReadOnlySet<T> (#103306)
* Add ReadOnlySet<T> * Add test
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5 files changed

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‎src/libraries/System.Collections/ref/System.Collections.cs

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@@ -411,6 +411,38 @@ void System.Collections.IEnumerator.Reset() { }
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}
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}
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}
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namespace System.Collections.ObjectModel
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{
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public partial class ReadOnlySet<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.IReadOnlySet<T>, System.Collections.Generic.ISet<T>, System.Collections.ICollection, System.Collections.IEnumerable
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{
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public ReadOnlySet(System.Collections.Generic.ISet<T> @set) { }
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public int Count { get { throw null; } }
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public static System.Collections.ObjectModel.ReadOnlySet<T> Empty { get { throw null; } }
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protected System.Collections.Generic.ISet<T> Set { get { throw null; } }
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bool System.Collections.Generic.ICollection<T>.IsReadOnly { get { throw null; } }
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bool System.Collections.ICollection.IsSynchronized { get { throw null; } }
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object System.Collections.ICollection.SyncRoot { get { throw null; } }
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public bool Contains(T item) { throw null; }
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public System.Collections.Generic.IEnumerator<T> GetEnumerator() { throw null; }
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public bool IsProperSubsetOf(System.Collections.Generic.IEnumerable<T> other) { throw null; }
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public bool IsProperSupersetOf(System.Collections.Generic.IEnumerable<T> other) { throw null; }
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public bool IsSubsetOf(System.Collections.Generic.IEnumerable<T> other) { throw null; }
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public bool IsSupersetOf(System.Collections.Generic.IEnumerable<T> other) { throw null; }
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public bool Overlaps(System.Collections.Generic.IEnumerable<T> other) { throw null; }
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public bool SetEquals(System.Collections.Generic.IEnumerable<T> other) { throw null; }
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void System.Collections.Generic.ICollection<T>.Add(T item) { }
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void System.Collections.Generic.ICollection<T>.Clear() { }
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void System.Collections.Generic.ICollection<T>.CopyTo(T[] array, int arrayIndex) { }
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bool System.Collections.Generic.ICollection<T>.Remove(T item) { throw null; }
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bool System.Collections.Generic.ISet<T>.Add(T item) { throw null; }
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void System.Collections.Generic.ISet<T>.ExceptWith(System.Collections.Generic.IEnumerable<T> other) { }
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void System.Collections.Generic.ISet<T>.IntersectWith(System.Collections.Generic.IEnumerable<T> other) { }
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void System.Collections.Generic.ISet<T>.SymmetricExceptWith(System.Collections.Generic.IEnumerable<T> other) { }
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void System.Collections.Generic.ISet<T>.UnionWith(System.Collections.Generic.IEnumerable<T> other) { }
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void System.Collections.ICollection.CopyTo(System.Array array, int index) { }
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System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { throw null; }
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}
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}
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#endif // !BUILDING_CORELIB_REFERENCE
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namespace System.Collections.Generic
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{

‎src/libraries/System.Collections/src/System.Collections.csproj

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@@ -16,9 +16,12 @@
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Link="Common\System\Collections\Generic\ICollectionDebugView.cs" />
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<Compile Include="$(CoreLibSharedDir)System\Collections\Generic\IDictionaryDebugView.cs"
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Link="Common\System\Collections\Generic\IDictionaryDebugView.cs" />
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<Compile Include="$(CoreLibSharedDir)System\Collections\ObjectModel\CollectionHelpers.cs"
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Link="Common\System\Collections\ObjectModel\CollectionHelpers.cs" />
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<Compile Include="System\Collections\Generic\LinkedList.cs" />
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<Compile Include="System\Collections\Generic\PriorityQueue.cs" />
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<Compile Include="System\Collections\Generic\PriorityQueueDebugView.cs" />
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<Compile Include="System\Collections\Generic\ReadOnlySet.cs" />
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<Compile Include="System\Collections\Generic\SortedDictionary.cs" />
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<Compile Include="System\Collections\Generic\SortedList.cs" />
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<Compile Include="System\Collections\Generic\SortedSet.cs" />

‎src/libraries/System.Collections/src/System/Collections/Generic/ReadOnlySet.cs

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@@ -0,0 +1,102 @@
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// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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using System.Collections.Generic;
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using System.Diagnostics;
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namespace System.Collections.ObjectModel
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{
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/// <summary>Represents a read-only, generic set of values.</summary>
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/// <typeparam name="T">The type of values in the set.</typeparam>
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[DebuggerDisplay("Count = {Count}")]
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public class ReadOnlySet<T> : IReadOnlySet<T>, ISet<T>, ICollection
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{
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/// <summary>The wrapped set.</summary>
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private readonly ISet<T> _set;
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/// <summary>Initializes a new instance of the <see cref="ReadOnlySet{T}"/> class that is a wrapper around the specified set.</summary>
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/// <param name="set">The set to wrap.</param>
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public ReadOnlySet(ISet<T> set)
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{
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ArgumentNullException.ThrowIfNull(set);
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_set = set;
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}
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/// <summary>Gets an empty <see cref="ReadOnlySet{T}"/>.</summary>
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public static ReadOnlySet<T> Empty { get; } = new ReadOnlySet<T>(new HashSet<T>());
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/// <summary>Gets the set that is wrapped by this <see cref="ReadOnlySet{T}"/> object.</summary>
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protected ISet<T> Set => _set;
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/// <inheritdoc/>
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public int Count => _set.Count;
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/// <inheritdoc/>
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public IEnumerator<T> GetEnumerator() =>
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_set.Count == 0 ? ((IEnumerable<T>)Array.Empty<T>()).GetEnumerator() :
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_set.GetEnumerator();
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/// <inheritdoc/>
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IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
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/// <inheritdoc/>
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public bool Contains(T item) => _set.Contains(item);
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/// <inheritdoc/>
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public bool IsProperSubsetOf(IEnumerable<T> other) => _set.IsProperSubsetOf(other);
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/// <inheritdoc/>
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public bool IsProperSupersetOf(IEnumerable<T> other) => _set.IsProperSupersetOf(other);
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/// <inheritdoc/>
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public bool IsSubsetOf(IEnumerable<T> other) => _set.IsSubsetOf(other);
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/// <inheritdoc/>
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public bool IsSupersetOf(IEnumerable<T> other) => _set.IsSupersetOf(other);
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/// <inheritdoc/>
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public bool Overlaps(IEnumerable<T> other) => _set.Overlaps(other);
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/// <inheritdoc/>
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public bool SetEquals(IEnumerable<T> other) => _set.SetEquals(other);
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/// <inheritdoc/>
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void ICollection<T>.CopyTo(T[] array, int arrayIndex) => _set.CopyTo(array, arrayIndex);
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/// <inheritdoc/>
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void ICollection.CopyTo(Array array, int index) => CollectionHelpers.CopyTo(_set, array, index);
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/// <inheritdoc/>
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bool ICollection<T>.IsReadOnly => true;
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/// <inheritdoc/>
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bool ICollection.IsSynchronized => false;
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/// <inheritdoc/>
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object ICollection.SyncRoot => _set is ICollection c ? c.SyncRoot : this;
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/// <inheritdoc/>
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bool ISet<T>.Add(T item) => throw new NotSupportedException();
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/// <inheritdoc/>
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void ISet<T>.ExceptWith(IEnumerable<T> other) => throw new NotSupportedException();
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/// <inheritdoc/>
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void ISet<T>.IntersectWith(IEnumerable<T> other) => throw new NotSupportedException();
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/// <inheritdoc/>
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void ISet<T>.SymmetricExceptWith(IEnumerable<T> other) => throw new NotSupportedException();
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/// <inheritdoc/>
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void ISet<T>.UnionWith(IEnumerable<T> other) => throw new NotSupportedException();
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/// <inheritdoc/>
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void ICollection<T>.Add(T item) => throw new NotSupportedException();
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/// <inheritdoc/>
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void ICollection<T>.Clear() => throw new NotSupportedException();
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/// <inheritdoc/>
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bool ICollection<T>.Remove(T item) => throw new NotSupportedException();
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}
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}

‎src/libraries/System.Collections/tests/Generic/ReadOnlySet/ReadOnlySetTests.cs

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@@ -0,0 +1,128 @@
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// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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using System.Collections.Generic;
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using Xunit;
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namespace System.Collections.ObjectModel.Tests
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{
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public class ReadOnlySetTests
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{
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[Fact]
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public void Ctor_NullSet_ThrowsArgumentNullException()
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{
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AssertExtensions.Throws<ArgumentNullException>("set", () => new ReadOnlySet<int>(null));
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}
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[Fact]
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public void Ctor_SetProperty_Roundtrips()
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{
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var set = new HashSet<int>();
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Assert.Same(set, new DerivedReadOnlySet<int>(set).Set);
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}
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[Fact]
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public void Empty_EmptyAndIdempotent()
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{
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Assert.Same(ReadOnlySet<int>.Empty, ReadOnlySet<int>.Empty);
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Assert.Empty(ReadOnlySet<int>.Empty);
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Assert.Same(ReadOnlySet<int>.Empty.GetEnumerator(), ReadOnlySet<int>.Empty.GetEnumerator());
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}
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[Fact]
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public void MembersDelegateToWrappedSet()
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{
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var set = new ReadOnlySet<int>(new HashSet<int>() { 1, 2, 3 });
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Assert.True(set.Contains(2));
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Assert.False(set.Contains(4));
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Assert.Equal(3, set.Count);
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Assert.True(set.IsProperSubsetOf([1, 2, 3, 4]));
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Assert.False(set.IsProperSubsetOf([1, 2, 5]));
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Assert.True(set.IsProperSupersetOf([1, 2]));
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Assert.False(set.IsProperSupersetOf([1, 4]));
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Assert.True(set.IsSubsetOf([1, 2, 3, 4]));
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Assert.False(set.IsSubsetOf([1, 2, 5]));
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Assert.True(set.IsSupersetOf([1, 2]));
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Assert.False(set.IsSupersetOf([1, 4]));
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Assert.True(set.Overlaps([-1, 0, 1]));
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Assert.False(set.Overlaps([-1, 0]));
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Assert.True(set.SetEquals([1, 2, 3]));
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Assert.False(set.SetEquals([1, 2, 4]));
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int[] result = new int[3];
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((ICollection<int>)set).CopyTo(result, 0);
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Assert.Equal(result, new int[] { 1, 2, 3 });
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Array.Clear(result);
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((ICollection)set).CopyTo(result, 0);
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Assert.Equal(result, new int[] { 1, 2, 3 });
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Assert.NotNull(set.GetEnumerator());
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}
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[Fact]
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public void ChangesToUnderlyingSetReflected()
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{
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var set = new HashSet<int> { 1, 2, 3 };
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var readOnlySet = new ReadOnlySet<int>(set);
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set.Add(4);
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Assert.Equal(4, readOnlySet.Count);
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Assert.True(readOnlySet.Contains(4));
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set.Remove(2);
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Assert.Equal(3, readOnlySet.Count);
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Assert.False(readOnlySet.Contains(2));
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}
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[Fact]
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public void IsReadOnly_True()
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{
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var set = new ReadOnlySet<int>(new HashSet<int> { 1, 2, 3 });
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Assert.True(((ICollection<int>)set).IsReadOnly);
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}
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[Fact]
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public void MutationThrows_CollectionUnmodified()
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{
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var set = new HashSet<int> { 1, 2, 3 };
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var readOnlySet = new ReadOnlySet<int>(set);
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Assert.Throws<NotSupportedException>(() => ((ICollection<int>)readOnlySet).Add(4));
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Assert.Throws<NotSupportedException>(() => ((ICollection<int>)readOnlySet).Remove(1));
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Assert.Throws<NotSupportedException>(() => ((ICollection<int>)readOnlySet).Clear());
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Assert.Throws<NotSupportedException>(() => ((ISet<int>)readOnlySet).Add(4));
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Assert.Throws<NotSupportedException>(() => ((ISet<int>)readOnlySet).ExceptWith([1, 2, 3]));
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Assert.Throws<NotSupportedException>(() => ((ISet<int>)readOnlySet).IntersectWith([1, 2, 3]));
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Assert.Throws<NotSupportedException>(() => ((ISet<int>)readOnlySet).SymmetricExceptWith([1, 2, 3]));
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Assert.Throws<NotSupportedException>(() => ((ISet<int>)readOnlySet).UnionWith([1, 2, 3]));
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Assert.Equal(3, set.Count);
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}
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[Fact]
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public void ICollection_Synchronization()
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{
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var set = new ReadOnlySet<int>(new HashSet<int> { 1, 2, 3 });
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Assert.False(((ICollection)set).IsSynchronized);
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Assert.Same(set, ((ICollection)set).SyncRoot);
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}
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private class DerivedReadOnlySet<T> : ReadOnlySet<T>
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{
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public DerivedReadOnlySet(HashSet<T> set) : base(set) { }
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public new ISet<T> Set => base.Set;
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}
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}
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}

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