From a188825be983a81633577330944002608ac694f1 Mon Sep 17 00:00:00 2001
From: Brad Wilson <dotnetguy@gmail.com>
Date: Tue, 18 Jan 2022 08:59:33 -0800
Subject: [PATCH] Port #2463 to v2

---
 src/xunit.assert.nuspec                       |  6 +++-
 src/xunit.assert/Asserts                      |  2 +-
 src/xunit.execution/xunit.execution.csproj    |  2 +-
 src/xunit.extensibility.core.nuspec           |  6 ++++
 src/xunit.extensibility.execution.nuspec      |  8 +++++-
 .../Asserts/CollectionAssertsTests.cs         | 28 +++++++++++++++++++
 6 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/src/xunit.assert.nuspec b/src/xunit.assert.nuspec
index 5b16003e2..ed2290fc0 100644
--- a/src/xunit.assert.nuspec
+++ b/src/xunit.assert.nuspec
@@ -17,6 +17,7 @@
       <group targetFramework="netstandard1.1">
         <dependency id="NETStandard.Library" version="1.6.1" />
       </group>
+      <group targetFramework="netstandard2.0" />
     </dependencies>
   </metadata>
   <files>
@@ -24,5 +25,8 @@
 
     <file src="xunit.assert\bin\$Configuration$\netstandard1.1\xunit.assert.dll" target="lib\netstandard1.1\" />
     <file src="xunit.assert\bin\$Configuration$\netstandard1.1\xunit.assert.xml" target="lib\netstandard1.1\" />
+
+    <file src="xunit.assert\bin\$Configuration$\netstandard1.1\xunit.assert.dll" target="lib\netstandard2.0\" />
+    <file src="xunit.assert\bin\$Configuration$\netstandard1.1\xunit.assert.xml" target="lib\netstandard2.0\" />
   </files>
-</package>
\ No newline at end of file
+</package>
diff --git a/src/xunit.assert/Asserts b/src/xunit.assert/Asserts
index 08ea727ab..43e3e208a 160000
--- a/src/xunit.assert/Asserts
+++ b/src/xunit.assert/Asserts
@@ -1 +1 @@
-Subproject commit 08ea727abe286ecc3bf340959d909cba7b9b195e
+Subproject commit 43e3e208a597bc1a4c77f2665f39f98e7401c157
diff --git a/src/xunit.execution/xunit.execution.csproj b/src/xunit.execution/xunit.execution.csproj
index 43174d1f7..90ec93954 100644
--- a/src/xunit.execution/xunit.execution.csproj
+++ b/src/xunit.execution/xunit.execution.csproj
@@ -6,7 +6,7 @@
     <DefineConstants>$(DefineConstants);XUNIT_FRAMEWORK</DefineConstants>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <RootNamespace>Xunit.Sdk</RootNamespace>
-    <TargetFrameworks>net452;netstandard1.1</TargetFrameworks>
+    <TargetFrameworks>net452;netstandard1.1;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/xunit.extensibility.core.nuspec b/src/xunit.extensibility.core.nuspec
index 4063c36ee..f3cad4d16 100644
--- a/src/xunit.extensibility.core.nuspec
+++ b/src/xunit.extensibility.core.nuspec
@@ -23,6 +23,9 @@
         <dependency id="NETStandard.Library" version="1.6.1" />
         <dependency id="xunit.abstractions" version="2.0.3" />
       </group>
+      <group targetFramework="netstandard2.0">
+        <dependency id="xunit.abstractions" version="2.0.3" />
+      </group>
     </dependencies>
   </metadata>
   <files>
@@ -36,5 +39,8 @@
 
     <file src="xunit.core\bin\$Configuration$\netstandard1.1\xunit.core.dll" target="lib\netstandard1.1\" />
     <file src="xunit.core\bin\$Configuration$\netstandard1.1\xunit.core.xml" target="lib\netstandard1.1\" />
+
+    <file src="xunit.core\bin\$Configuration$\netstandard1.1\xunit.core.dll" target="lib\netstandard2.0\" />
+    <file src="xunit.core\bin\$Configuration$\netstandard1.1\xunit.core.xml" target="lib\netstandard2.0\" />
   </files>
 </package>
diff --git a/src/xunit.extensibility.execution.nuspec b/src/xunit.extensibility.execution.nuspec
index 3c5039fc0..d42c30c07 100644
--- a/src/xunit.extensibility.execution.nuspec
+++ b/src/xunit.extensibility.execution.nuspec
@@ -20,6 +20,9 @@
         <dependency id="NETStandard.Library" version="1.6.1" />
         <dependency id="xunit.extensibility.core" version="[$PackageVersion$]" />
       </group>
+      <group targetFramework="netstandard2.0">
+        <dependency id="xunit.extensibility.core" version="[$PackageVersion$]" />
+      </group>
     </dependencies>
   </metadata>
   <files>
@@ -30,5 +33,8 @@
 
     <file src="xunit.execution\bin\$Configuration$\netstandard1.1\xunit.execution.dotnet.dll" target="lib\netstandard1.1\" />
     <file src="xunit.execution\bin\$Configuration$\netstandard1.1\xunit.execution.dotnet.xml" target="lib\netstandard1.1\" />
+
+    <file src="xunit.execution\bin\$Configuration$\netstandard2.0\xunit.execution.dotnet.dll" target="lib\netstandard2.0\" />
+    <file src="xunit.execution\bin\$Configuration$\netstandard2.0\xunit.execution.dotnet.xml" target="lib\netstandard2.0\" />
   </files>
-</package>
\ No newline at end of file
+</package>
diff --git a/test/test.xunit.assert/Asserts/CollectionAssertsTests.cs b/test/test.xunit.assert/Asserts/CollectionAssertsTests.cs
index b2f0bbbf4..9b51915d7 100644
--- a/test/test.xunit.assert/Asserts/CollectionAssertsTests.cs
+++ b/test/test.xunit.assert/Asserts/CollectionAssertsTests.cs
@@ -925,6 +925,14 @@ public static void Equivalence()
 
 			Assert.Equal(expected, actual);
 		}
+
+		[Fact]
+		public static void EnumeratesOnlyOnce()
+		{
+			var expected = new[] { 1, 2, 3, 4, 5 };
+			var actual = new RunOnceEnumerable<int>(expected);
+			Assert.Equal(expected, actual);
+		}
 	}
 
 	public class EqualDictionary
@@ -1350,6 +1358,26 @@ public static void PredicateTooManyMatches()
 		}
 	}
 
+	sealed class RunOnceEnumerable<T> : IEnumerable<T>
+	{
+		private readonly IEnumerable<T> _source;
+		private bool _called;
+
+		public RunOnceEnumerable(IEnumerable<T> source)
+		{
+			_source = source;
+		}
+
+		public IEnumerator<T> GetEnumerator()
+		{
+			Assert.False(_called, "GetEnumerator() was called more than once");
+			_called = true;
+			return _source.GetEnumerator();
+		}
+
+		IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+	}
+
 	sealed class SpyEnumerator<T> : IEnumerable<T>, IEnumerator<T>
 	{
 		IEnumerator<T>? innerEnumerator;