CSHARP-2948: Check uses of string.Normalize in SaslPrepHelper when targetting netstandard2.0 (mongodb#516)

Author: MikalaiMazurenka

src/MongoDB.Driver.Core/Core/Authentication/SaslPrepHelper.cs

@@ -103,12 +103,12 @@ private static string SaslPrep(string str, bool allowUnassigned)
 
             var mappedString = new string(chars.Take(length).ToArray());
             // 2. Normalize
-#if NET452
-            var normalized = mappedString.Normalize(NormalizationForm.FormKC);
-#else
-            // String normalization step in the .NET Standard version of the driver is skipped due to a lack of a string
+#if NETSTANDARD1_5
+            // String normalization step in the .NET Standard 1.5 version of the driver is skipped due to a lack of a string
             // normalization function.
             var normalized = mappedString;
+#else
+            var normalized = mappedString.Normalize(NormalizationForm.FormKC);
 #endif
             var containsRandALCat = false;
             var containsLCat = false;

tests/MongoDB.Driver.Core.Tests/Core/Authentication/SaslPrepHelperTests.cs

@@ -26,9 +26,6 @@ namespace MongoDB.Driver.Core.Authentication
     /// </summary>
     public class SaslPrepHelperTests
     {
-        // Currently, we only support SaslPrep in .NET Framework due to a lack of a string normalization function in
-        // .NET Standard
-#if NET452
         [Fact]
         public void SaslPrepQuery_accepts_undefined_codepoint()
         {     
@@ -52,6 +49,8 @@ public void SaslPrepStored_maps_space_equivalents_to_space(string expected, stri
             SaslPrepHelper.SaslPrepStored(input).Should().Be(expected);
         }
 
+#if !NETCOREAPP1_1
+// Normalization is not supported in netstandard 1.5 due to a lack of a string normalization function.
         [Theory]
         [ParameterAttributeData]
         [InlineData("IX", "\u2168")] // "IX", Roman numeral nine
@@ -62,6 +61,7 @@ public void SaslPrepStored_returns_expected_output_when_passed_nonNormalized_str
         {
             SaslPrepHelper.SaslPrepStored(nonNormalizedStr).Should().Be(expected);
         }
+#endif
 
         [Theory]
         [ParameterAttributeData]
@@ -80,8 +80,11 @@ public void SaslPrepStored_returns_expected_output_when_passed_partially_SaslPre
         [InlineData("user", "user")]
         [InlineData("user=", "user=")]
         [InlineData("USER", "USER")]
+#if !NETCOREAPP1_1
+// Normalization is not supported in netstandard 1.5 due to a lack of a string normalization function.
         [InlineData("a", "\u00AA")]
         [InlineData("IX", "\u2168")]
+#endif
         public void SaslPrepStored_returns_expected_output_when_passed_Rfc4013_examples(string expected, string input)
         {
             SaslPrepHelper.SaslPrepStored(input).Should().Be(expected);
@@ -117,7 +120,6 @@ public void SaslPrepStored_throws_exception_when_passed_an_undefined_codepoint()
             exception.Should().BeOfType<ArgumentException>();
             exception.Message.Should().Be("Character at position 3 is unassigned");
         }
-#endif
 
         private static readonly Lazy<int> _unassignedCodePoint = new Lazy<int>(FindUnassignedCodePoint);