Improve Span/ReadOnlySpan test coverage (#26342)

Author: jkotas

src/System.Memory/tests/Memory/Span.cs

@@ -66,10 +66,10 @@ public static void SpanFromCtorArrayZeroLength()
             Memory<int> memory;
 
             memory = new Memory<int>(empty);
-            memory.Span.Validate();
+            memory.Span.ValidateNonNullEmpty();
 
             memory = new Memory<int>(empty, 0, empty.Length);
-            memory.Span.Validate();
+            memory.Span.ValidateNonNullEmpty();
 
             OwnedMemory<int> owner = new CustomMemoryForTest<int>(empty);
             owner.Memory.Span.Validate();

src/System.Memory/tests/Performance/System.Memory.Performance.Tests.csproj

@@ -3,6 +3,7 @@
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
   <PropertyGroup>
     <IncludePerformanceTests>true</IncludePerformanceTests>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <ProjectGuid>{18482C55-6B57-41E8-BBC4-383B9E2C7AA2}</ProjectGuid>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Debug|AnyCPU'" />

src/System.Memory/tests/ReadOnlyMemory/Span.cs

@@ -66,10 +66,10 @@ public static void SpanFromCtorArrayZeroLength()
             ReadOnlyMemory<int> memory;
 
             memory = new ReadOnlyMemory<int>(empty);
-            memory.Span.Validate();
+            memory.Span.ValidateNonNullEmpty();
 
             memory = new ReadOnlyMemory<int>(empty, 0, empty.Length);
-            memory.Span.Validate();
+            memory.Span.ValidateNonNullEmpty();
 
             OwnedMemory<int> owner = new CustomMemoryForTest<int>(empty);
             ((ReadOnlyMemory<int>)owner.Memory).Span.Validate();

src/System.Memory/tests/ReadOnlySpan/AsReadOnlySpan.cs

@@ -46,7 +46,7 @@ public static void EmptyArrayAsReadOnlySpan()
         {
             int[] empty = Array.Empty<int>();
             ReadOnlySpan<int> span = empty.AsReadOnlySpan();
-            span.Validate();
+            span.ValidateNonNullEmpty();
         }
 
         [Fact]
@@ -86,12 +86,12 @@ public static void ZeroLengthArraySegmentAsReadOnlySpan()
             int[] empty = Array.Empty<int>();
             ArraySegment<int> emptySegment = new ArraySegment<int>(empty);
             ReadOnlySpan<int> span = emptySegment.AsReadOnlySpan();
-            span.Validate();
+            span.ValidateNonNullEmpty();
 
             int[] a = { 19, -17 };
             ArraySegment<int> segmentInt = new ArraySegment<int>(a, 1, 0);
             ReadOnlySpan<int> spanInt = segmentInt.AsReadOnlySpan();
-            spanInt.Validate();
+            spanInt.ValidateNonNullEmpty();
         }
 
         [Fact]
@@ -108,8 +108,7 @@ public static void StringAsReadOnlySpanEmptyString()
         {
             string s = "";
             ReadOnlySpan<char> span = s.AsReadOnlySpan();
-            char[] expected = s.ToCharArray();
-            span.Validate(expected);
+            span.ValidateNonNullEmpty();
         }
 
         [Fact]

src/System.Memory/tests/ReadOnlySpan/CtorArray.cs

@@ -63,10 +63,10 @@ public static void CtorArrayZeroLength()
             ReadOnlySpan<int> span;
 
             span = new ReadOnlySpan<int>(empty);
-            span.Validate();
+            span.ValidateNonNullEmpty();
 
             span = new ReadOnlySpan<int>(empty, 0, empty.Length);
-            span.Validate();
+            span.ValidateNonNullEmpty();
         }
 
         [Fact]

src/System.Memory/tests/ReadOnlySpan/CtorArrayIntInt.cs

@@ -73,7 +73,7 @@ public static void CtorArrayIntIntStartEqualsLength()
             // Valid for start to equal the array length. This returns an empty span that starts "just past the array."
             int[] a = { 91, 92, 93 };
             ReadOnlySpan<int> span = new ReadOnlySpan<int>(a, 3, 0);
-            span.Validate();
+            span.ValidateNonNullEmpty();
         }
     }
 }

src/System.Memory/tests/ReadOnlySpan/NonPortableCast.cs

@@ -11,7 +11,7 @@ namespace System.SpanTests
     public static partial class ReadOnlySpanTests
     {
         [Fact]
-        public static void PortableCastUIntToUShort()
+        public static void NonPortableCastUIntToUShort()
         {
             uint[] a = { 0x44332211, 0x88776655 };
             ReadOnlySpan<uint> span = new ReadOnlySpan<uint>(a);
@@ -22,14 +22,34 @@ public static void PortableCastUIntToUShort()
         }
 
         [Fact]
-        public static void PortableCastToTypeContainsReferences()
+        public static void NonPortableCastShortToLong()
+        {
+            short[] a = { 0x1234, 0x2345, 0x3456, 0x4567, 0x5678 };
+            ReadOnlySpan<short> span = new ReadOnlySpan<short>(a);
+            ReadOnlySpan<long> asLong = span.NonPortableCast<short, long>();
+
+            Assert.True(Unsafe.AreSame<long>(ref Unsafe.As<short, long>(ref MemoryMarshal.GetReference(span)), ref MemoryMarshal.GetReference(asLong)));
+            asLong.Validate<long>(0x4567345623451234);
+        }
+
+        [Fact]
+        public static unsafe void NonPortableCastOverflow()
+        {
+            ReadOnlySpan<TestHelpers.TestStructExplicit> span = new ReadOnlySpan<TestHelpers.TestStructExplicit>(null, Int32.MaxValue);
+
+            TestHelpers.AssertThrows<OverflowException, TestHelpers.TestStructExplicit>(span, (_span) => _span.NonPortableCast<TestHelpers.TestStructExplicit, byte>().DontBox());
+            TestHelpers.AssertThrows<OverflowException, TestHelpers.TestStructExplicit>(span, (_span) => _span.NonPortableCast<TestHelpers.TestStructExplicit, ulong>().DontBox());
+        }
+
+        [Fact]
+        public static void NonPortableCastToTypeContainsReferences()
         {
             ReadOnlySpan<uint> span = new ReadOnlySpan<uint>(Array.Empty<uint>());
             TestHelpers.AssertThrows<ArgumentException, uint>(span, (_span) => _span.NonPortableCast<uint, StructWithReferences>().DontBox());
         }
 
         [Fact]
-        public static void PortableCastFromTypeContainsReferences()
+        public static void NonPortableCastFromTypeContainsReferences()
         {
             ReadOnlySpan<StructWithReferences> span = new ReadOnlySpan<StructWithReferences>(Array.Empty<StructWithReferences>());
             TestHelpers.AssertThrows<ArgumentException, StructWithReferences>(span, (_span) => _span.NonPortableCast<StructWithReferences, uint>().DontBox());

src/System.Memory/tests/Span/AsSpan.cs

@@ -39,7 +39,7 @@ public static void ZeroLengthArrayAsSpan()
         {
             int[] empty = Array.Empty<int>();
             Span<int> span = empty.AsSpan();
-            span.Validate();
+            span.ValidateNonNullEmpty();
         }
 
         [Fact]
@@ -79,12 +79,12 @@ public static void ZeroLengthArraySegmentAsSpan()
             int[] empty = Array.Empty<int>();
             ArraySegment<int> segmentEmpty = new ArraySegment<int>(empty);
             Span<int> spanEmpty = segmentEmpty.AsSpan();
-            spanEmpty.Validate();
+            spanEmpty.ValidateNonNullEmpty();
 
             int[] a = { 91, 92, -93, 94 };
             ArraySegment<int> segmentInt = new ArraySegment<int>(a, 0, 0);
             Span<int> spanInt = segmentInt.AsSpan();
-            spanInt.Validate();
+            spanInt.ValidateNonNullEmpty();
         }
     }
 }

src/System.Memory/tests/Span/CtorArray.cs

@@ -62,10 +62,10 @@ public static void CtorArrayZeroLength()
             Span<int> span;
 
             span = new Span<int>(empty);
-            span.Validate();
+            span.ValidateNonNullEmpty();
 
             span = new Span<int>(empty, 0, empty.Length);
-            span.Validate();
+            span.ValidateNonNullEmpty();
         }
 
         [Fact]

src/System.Memory/tests/Span/CtorArrayIntInt.cs

@@ -73,7 +73,7 @@ public static void CtorArrayIntIntStartEqualsLength()
             // Valid for start to equal the array length. This returns an empty span that starts "just past the array."
             int[] a = { 91, 92, 93 };
             Span<int> span = new Span<int>(a, 3, 0);
-            span.Validate();
+            span.ValidateNonNullEmpty();
         }
     }
 }