Added tests (working)

Author: Nick-Nuon

src/Ascii.cs

@@ -133,7 +133,7 @@ public static unsafe bool SIMDIsAscii(this ReadOnlySpan<char> s)
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal static unsafe nuint GetIndexOfFirstNonAsciiByte(byte* pBuffer, nuint bufferLength)
+        public static unsafe nuint GetIndexOfFirstNonAsciiByte(byte* pBuffer, nuint bufferLength)
         {
             byte* pBufferEnd = pBuffer + bufferLength;
             byte* pCurrent = pBuffer;

test/AsciiTest.cs

@@ -1,5 +1,6 @@
 namespace tests;
 using System.Text;
+using SimdUnicode;
 
 //TODO (Nick Nuon): Test UTF8 Generator works correctly
 
@@ -113,7 +114,7 @@ public void Test_random_ASCII_sequences_of_varying_lengths()
             }
 
             // Print the validation results
-            Console.WriteLine($"For {length}-byte sequences, {validSequencesCount * 100.0 / NUM_TRIALS}% were valid ASCII.");
+            // Console.WriteLine($"For {length}-byte sequences, {validSequencesCount * 100.0 / NUM_TRIALS}% were valid ASCII.");
 
             // Assertion or check to ensure all sequences were valid ASCII
             if (validSequencesCount != NUM_TRIALS)
@@ -123,5 +124,65 @@ public void Test_random_ASCII_sequences_of_varying_lengths()
         }
     }
 
+
+    [Fact]
+    // This mimics the no_error_ASCII test
+    public void TestNoErrorASCII()
+    {
+        const int NUM_TRIALS = 1000;
+        const int LENGTH = 512;
+        RandomUtf8 utf8Generator = new RandomUtf8(0, 100, 0, 0, 0);  // Only ASCII/one-bytes
+
+        for (int trial = 0; trial < NUM_TRIALS; trial++)
+        {
+            byte[] ascii = utf8Generator.Generate(LENGTH);
+            
+            unsafe
+            {
+                fixed (byte* pAscii = ascii)
+                {
+                    nuint result = Ascii.GetIndexOfFirstNonAsciiByte(pAscii, (nuint)ascii.Length);
+                    if (result != (nuint)ascii.Length)
+                    {
+                        throw new Exception($"Unexpected non-ASCII character found at index {result}");
+                    }
+                }
+            }
+        }
+    }
+
+    [Fact]
+    // This mimics the error_ASCII test
+    public void TestErrorASCII()
+    {
+        const int NUM_TRIALS = 1000;
+        const int LENGTH = 512;
+        RandomUtf8 utf8Generator = new RandomUtf8(0, 100, 0, 0, 0);  // Only ASCII/one-bytes
+
+        for (int trial = 0; trial < NUM_TRIALS; trial++)
+        {
+            byte[] ascii = utf8Generator.Generate(LENGTH);
+
+            for (int i = 0; i < ascii.Length; i++)
+            {
+                ascii[i] += 0b10000000;
+
+                unsafe
+                {
+                    fixed (byte* pAscii = ascii)
+                    {
+                        nuint result = Ascii.GetIndexOfFirstNonAsciiByte(pAscii, (nuint)ascii.Length);
+                        if (result != (nuint)i)
+                        {
+                            throw new Exception($"Expected non-ASCII character at index {i}, but found at index {result}");
+                        }
+                    }
+                }
+
+                ascii[i] -= 0b10000000;
+            }
+        }
+    }
+
 
 }