Testing GetHashCode works properly when using string with embedded null (#27296)

* Testing GetHashCode works properly when using string with embedded null

Related to #27098

* Adding disabled test for future tracking in netfx for GetHashCode.

Author: maryamariyan

src/System.Runtime.Extensions/tests/System/StringComparer.cs

@@ -26,12 +26,24 @@ public static void TestOrdinal()
             VerifyComparer(StringComparer.OrdinalIgnoreCase, true);
         }
 
+        [Fact]
+        [ActiveIssue(27098, TargetFrameworkMonikers.NetFramework)]
+        public static void TestOrdinal_EmbeddedNull_ReturnsDifferentHashCodes()
+        {
+            StringComparer sc = StringComparer.Ordinal;
+            Assert.NotEqual(sc.GetHashCode("\0AAAAAAAAA"), sc.GetHashCode("\0BBBBBBBBBBBB"));
+            sc = StringComparer.OrdinalIgnoreCase;
+            Assert.NotEqual(sc.GetHashCode("\0AAAAAAAAA"), sc.GetHashCode("\0BBBBBBBBBBBB"));
+        }
+
         private static void VerifyComparer(StringComparer sc, bool ignoreCase)
         {
             String s1 = "Hello";
             String s1a = "Hello";
             String s1b = "HELLO";
             String s2 = "There";
+            String aa = "\0AAAAAAAAA";
+            String bb = "\0BBBBBBBBBBBB";
 
             Assert.True(sc.Equals(s1, s1a));
             Assert.True(sc.Equals(s1, s1a));
@@ -52,6 +64,12 @@ private static void VerifyComparer(StringComparer sc, bool ignoreCase)
             Assert.Equal(ignoreCase, sc.Equals(s1, s1b));
             Assert.Equal(ignoreCase, ((IEqualityComparer)sc).Equals(s1, s1b));
 
+            Assert.NotEqual(0, ((IComparer)sc).Compare(aa, bb));
+            Assert.False(sc.Equals(aa, bb));
+            Assert.False(((IEqualityComparer)sc).Equals(aa, bb));
+            Assert.True(sc.Compare(aa, bb) < 0);
+            Assert.True(((IComparer)sc).Compare(aa, bb) < 0);
+
             int result = sc.Compare(s1, s1b);
             if (ignoreCase)
                 Assert.Equal(0, result);

src/System.Runtime/tests/System/StringTests.cs

@@ -1040,6 +1040,13 @@ public static void GetEnumerator_Generic_Invalid()
             Assert.Throws<InvalidOperationException>(() => enumerator.Current);
         }
 
+        [Fact]
+        [ActiveIssue(27098, TargetFrameworkMonikers.NetFramework)]
+        public static void GetHashCode_EmbeddedNull_ReturnsDifferentHashCodes()
+        {
+            Assert.NotEqual("\0AAAAAAAAA".GetHashCode(), "\0BBBBBBBBBBBB".GetHashCode());
+        }
+
         [Theory]
         // CurrentCulture
         [InlineData("Hello", "Hello", StringComparison.CurrentCulture, true)]
@@ -1053,6 +1060,7 @@ public static void GetEnumerator_Generic_Invalid()
         [InlineData("", "Hello", StringComparison.CurrentCulture, false)]
         [InlineData("", "", StringComparison.CurrentCulture, true)]
         [InlineData("123", 123, StringComparison.CurrentCulture, false)] // Not a string
+        [InlineData("\0AAAAAAAAA", "\0BBBBBBBBBBBB", StringComparison.CurrentCulture, false)]
         // CurrentCultureIgnoreCase
         [InlineData("Hello", "Hello", StringComparison.CurrentCultureIgnoreCase, true)]
         [InlineData("Hello", "hello", StringComparison.CurrentCultureIgnoreCase, true)]
@@ -1065,6 +1073,7 @@ public static void GetEnumerator_Generic_Invalid()
         [InlineData("", "Hello", StringComparison.CurrentCultureIgnoreCase, false)]
         [InlineData("", "", StringComparison.CurrentCultureIgnoreCase, true)]
         [InlineData("123", 123, StringComparison.CurrentCultureIgnoreCase, false)] // Not a string
+        [InlineData("\0AAAAAAAAA", "\0BBBBBBBBBBBB", StringComparison.CurrentCultureIgnoreCase, false)]
         // InvariantCulture
         [InlineData("Hello", "Hello", StringComparison.InvariantCulture, true)]
         [InlineData("Hello", "hello", StringComparison.InvariantCulture, false)]
@@ -1076,7 +1085,8 @@ public static void GetEnumerator_Generic_Invalid()
         [InlineData("Hello", "", StringComparison.InvariantCulture, false)]
         [InlineData("", "Hello", StringComparison.InvariantCulture, false)]
         [InlineData("", "", StringComparison.InvariantCulture, true)]
-        [InlineData("123", 123, StringComparison.InvariantCultureIgnoreCase, false)] // Not a string
+        [InlineData("123", 123, StringComparison.InvariantCulture, false)] // Not a string
+        [InlineData("\0AAAAAAAAA", "\0BBBBBBBBBBBB", StringComparison.InvariantCulture, false)]
         // InvariantCultureIgnoreCase
         [InlineData("Hello", "Hello", StringComparison.InvariantCultureIgnoreCase, true)]
         [InlineData("Hello", "hello", StringComparison.InvariantCultureIgnoreCase, true)]
@@ -1089,6 +1099,7 @@ public static void GetEnumerator_Generic_Invalid()
         [InlineData("", "Hello", StringComparison.InvariantCultureIgnoreCase, false)]
         [InlineData("", "", StringComparison.InvariantCultureIgnoreCase, true)]
         [InlineData("123", 123, StringComparison.InvariantCultureIgnoreCase, false)] // Not a string
+        [InlineData("\0AAAAAAAAA", "\0BBBBBBBBBBBB", StringComparison.InvariantCultureIgnoreCase, false)]
         // Ordinal
         [InlineData("Hello", "Hello", StringComparison.Ordinal, true)]
         [InlineData("Hello", "hello", StringComparison.Ordinal, false)]
@@ -1118,6 +1129,7 @@ public static void GetEnumerator_Generic_Invalid()
         [InlineData("", "Hello", StringComparison.OrdinalIgnoreCase, false)]
         [InlineData("", "", StringComparison.OrdinalIgnoreCase, true)]
         [InlineData("123", 123, StringComparison.OrdinalIgnoreCase, false)] // Not a string
+        [InlineData("\0AAAAAAAAA", "\0BBBBBBBBBBBB", StringComparison.OrdinalIgnoreCase, false)]
         public static void Equals(string s1, object obj, StringComparison comparisonType, bool expected)
         {
             string s2 = obj as string;