Allow Base64Decoder to ignore space chars, add IsValid methods and tests

src/libraries/System.Memory/tests/Base64/Base64DecoderUnitTests.cs

@@ -1,12 +1,13 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Linq;
 using System.Text;
 using Xunit;
 
 namespace System.Buffers.Text.Tests
 {
-    public class Base64DecoderUnitTests
+    public class Base64DecoderUnitTests : Base64TestBase
     {
         [Fact]
         public void BasicDecoding()
@@ -144,7 +145,7 @@ public void DecodingOutputTooSmall()
 
                 Span<byte> decodedBytes = new byte[3];
                 int consumed, written;
-                if (numBytes % 4 == 0)
+                if (numBytes >= 8)
                 {
                     Assert.True(OperationStatus.DestinationTooSmall ==
                         Base64.DecodeFromUtf8(source, decodedBytes, out consumed, out written), "Number of Input Bytes: " + numBytes);
@@ -360,7 +361,9 @@ public void DecodingInvalidBytes(bool isFinalBlock)
                 for (int i = 0; i < invalidBytes.Length; i++)
                 {
                     // Don't test padding (byte 61 i.e. '='), which is tested in DecodingInvalidBytesPadding
-                    if (invalidBytes[i] == Base64TestHelper.EncodingPad)
+                    // Don't test chars to be ignored (spaces: 9, 10, 13, 32 i.e. '\n', '\t', '\r', ' ')
+                    if (invalidBytes[i] == Base64TestHelper.EncodingPad
+                        || Base64TestHelper.IsByteToBeIgnored(invalidBytes[i]))
                         continue;
 
                     // replace one byte with an invalid input
@@ -555,7 +558,9 @@ public void DecodeInPlaceInvalidBytes()
                     Span<byte> buffer = "2222PPPP"u8.ToArray(); // valid input
 
                     // Don't test padding (byte 61 i.e. '='), which is tested in DecodeInPlaceInvalidBytesPadding
-                    if (invalidBytes[i] == Base64TestHelper.EncodingPad)
+                    // Don't test chars to be ignored (spaces: 9, 10, 13, 32 i.e. '\n', '\t', '\r', ' ')
+                    if (invalidBytes[i] == Base64TestHelper.EncodingPad
+                        || Base64TestHelper.IsByteToBeIgnored(invalidBytes[i]))
                         continue;
 
                     // replace one byte with an invalid input
@@ -581,7 +586,7 @@ public void DecodeInPlaceInvalidBytes()
             {
                 Span<byte> buffer = "2222PPP"u8.ToArray(); // incomplete input
                 Assert.Equal(OperationStatus.InvalidData, Base64.DecodeFromUtf8InPlace(buffer, out int bytesWritten));
-                Assert.Equal(0, bytesWritten);
+                Assert.Equal(3, bytesWritten);
             }
         }
 
@@ -654,5 +659,63 @@ public void DecodeInPlaceInvalidBytesPadding()
             }
         }
 
+        [Theory]
+        [MemberData(nameof(ValidBase64Strings_WithCharsThatMustBeIgnored))]
+        public void BasicDecodingIgnoresCharsToBeIgnoredAsConvertToBase64Does(string utf8WithCharsToBeIgnored, byte[] expectedBytes)
+        {
+            byte[] utf8BytesWithByteToBeIgnored = UTF8Encoding.UTF8.GetBytes(utf8WithCharsToBeIgnored);
+            byte[] resultBytes = new byte[5];
+            OperationStatus result = Base64.DecodeFromUtf8(utf8BytesWithByteToBeIgnored, resultBytes, out int bytesConsumed, out int bytesWritten);
+
+            // Control value from Convert.FromBase64String
+            byte[] stringBytes = Convert.FromBase64String(utf8WithCharsToBeIgnored);
+
+            Assert.Equal(OperationStatus.Done, result);
+            Assert.Equal(8, bytesConsumed);
+            Assert.Equal(expectedBytes.Length, bytesWritten);
+            Assert.True(expectedBytes.SequenceEqual(resultBytes));
+            Assert.True(stringBytes.SequenceEqual(resultBytes));
+        }
+
+        [Theory]
+        [MemberData(nameof(ValidBase64Strings_WithCharsThatMustBeIgnored))]
+        public void DecodeInPlaceIgnoresCharsToBeIgnoredAsConvertToBase64Does(string utf8WithCharsToBeIgnored, byte[] expectedBytes)
+        {
+            Span<byte> utf8BytesWithByteToBeIgnored = UTF8Encoding.UTF8.GetBytes(utf8WithCharsToBeIgnored);
+            OperationStatus result = Base64.DecodeFromUtf8InPlace(utf8BytesWithByteToBeIgnored, out int bytesWritten);
+            Span<byte> bytesOverwritten = utf8BytesWithByteToBeIgnored.Slice(0, bytesWritten);
+            byte[] resultBytesArray = bytesOverwritten.ToArray();
+
+            // Control value from Convert.FromBase64String
+            byte[] stringBytes = Convert.FromBase64String(utf8WithCharsToBeIgnored);
+
+            Assert.Equal(OperationStatus.Done, result);
+            Assert.Equal(expectedBytes.Length, bytesWritten);
+            Assert.True(expectedBytes.SequenceEqual(resultBytesArray));
+            Assert.True(stringBytes.SequenceEqual(resultBytesArray));
+        }
+
+        [Theory]
+        [MemberData(nameof(StringsOnlyWithCharsToBeIgnored))]
+        public void BasicDecodingWithOnlyCharsToBeIgnored(string utf8WithCharsToBeIgnored)
+        {
+            byte[] utf8BytesWithByteToBeIgnored = UTF8Encoding.UTF8.GetBytes(utf8WithCharsToBeIgnored);
+            byte[] resultBytes = new byte[5];
+            OperationStatus result = Base64.DecodeFromUtf8(utf8BytesWithByteToBeIgnored, resultBytes, out int bytesConsumed, out int bytesWritten);
+
+            Assert.Equal(OperationStatus.Done, result);
+            Assert.Equal(0, bytesWritten);
+        }
+
+        [Theory]
+        [MemberData(nameof(StringsOnlyWithCharsToBeIgnored))]
+        public void DecodingInPlaceWithOnlyCharsToBeIgnored(string utf8WithCharsToBeIgnored)
+        {
+            Span<byte> utf8BytesWithByteToBeIgnored = UTF8Encoding.UTF8.GetBytes(utf8WithCharsToBeIgnored);
+            OperationStatus result = Base64.DecodeFromUtf8InPlace(utf8BytesWithByteToBeIgnored, out int bytesWritten);
+
+            Assert.Equal(OperationStatus.Done, result);
+            Assert.Equal(0, bytesWritten);
+        }
     }
 }

src/libraries/System.Memory/tests/Base64/Base64TestBase.cs

@@ -0,0 +1,110 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Generic;
+using System.Text;
+
+namespace System.Buffers.Text.Tests
+{
+    public class Base64TestBase
+    {
+        public static IEnumerable<object[]> ValidBase64Strings_WithCharsThatMustBeIgnored()
+        {
+            // Create a Base64 string
+            string text = "a b c";
+            byte[] utf8Bytes = Encoding.UTF8.GetBytes(text);
+            string base64Utf8String = Convert.ToBase64String(utf8Bytes);
+
+            // Split the base64 string in half
+            int stringLength = base64Utf8String.Length / 2;
+            string firstSegment = base64Utf8String.Substring(0, stringLength);
+            string secondSegment = base64Utf8String.Substring(stringLength, stringLength);
+
+            // Insert ignored chars between the base 64 string
+            // One will have 1 char, another will have 3
+
+            // Line feed
+            yield return new object[] { GetBase64StringWithPassedCharInsertedInTheMiddle(Convert.ToChar(9), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedInTheMiddle(Convert.ToChar(9), 3), utf8Bytes };
+
+            // Horizontal tab
+            yield return new object[] { GetBase64StringWithPassedCharInsertedInTheMiddle(Convert.ToChar(10), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedInTheMiddle(Convert.ToChar(10), 3), utf8Bytes };
+
+            // Carriage return
+            yield return new object[] { GetBase64StringWithPassedCharInsertedInTheMiddle(Convert.ToChar(13), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedInTheMiddle(Convert.ToChar(13), 3), utf8Bytes };
+
+            // Space
+            yield return new object[] { GetBase64StringWithPassedCharInsertedInTheMiddle(Convert.ToChar(32), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedInTheMiddle(Convert.ToChar(32), 3), utf8Bytes };
+
+            string GetBase64StringWithPassedCharInsertedInTheMiddle(char charToInsert, int numberOfTimesToInsert) => $"{firstSegment}{new string(charToInsert, numberOfTimesToInsert)}{secondSegment}";
+
+            // Insert ignored chars at the start of the base 64 string
+            // One will have 1 char, another will have 3
+
+            // Line feed
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheStart(Convert.ToChar(9), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheStart(Convert.ToChar(9), 3), utf8Bytes };
+
+            // Horizontal tab
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheStart(Convert.ToChar(10), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheStart(Convert.ToChar(10), 3), utf8Bytes };
+
+            // Carriage return
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheStart(Convert.ToChar(13), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheStart(Convert.ToChar(13), 3), utf8Bytes };
+
+            // Space
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheStart(Convert.ToChar(32), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheStart(Convert.ToChar(32), 3), utf8Bytes };
+
+            string GetBase64StringWithPassedCharInsertedAtTheStart(char charToInsert, int numberOfTimesToInsert) => $"{new string(charToInsert, numberOfTimesToInsert)}{firstSegment}{secondSegment}";
+
+            // Insert ignored chars at the end of the base 64 string
+            // One will have 1 char, another will have 3
+
+            // Line feed
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheEnd(Convert.ToChar(9), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheEnd(Convert.ToChar(9), 3), utf8Bytes };
+
+            // Horizontal tab
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheEnd(Convert.ToChar(10), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheEnd(Convert.ToChar(10), 3), utf8Bytes };
+
+            // Carriage return
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheEnd(Convert.ToChar(13), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheEnd(Convert.ToChar(13), 3), utf8Bytes };
+
+            // Space
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheEnd(Convert.ToChar(32), 1), utf8Bytes };
+            yield return new object[] { GetBase64StringWithPassedCharInsertedAtTheEnd(Convert.ToChar(32), 3), utf8Bytes };
+
+            string GetBase64StringWithPassedCharInsertedAtTheEnd(char charToInsert, int numberOfTimesToInsert) => $"{firstSegment}{secondSegment}{new string(charToInsert, numberOfTimesToInsert)}";
+        }
+
+        public static IEnumerable<object[]> StringsOnlyWithCharsToBeIgnored()
+        {
+            // One will have 1 char, another will have 3
+
+            // Line feed
+            yield return new object[] { GetRepeatedChar(Convert.ToChar(9), 1) };
+            yield return new object[] { GetRepeatedChar(Convert.ToChar(9), 3) };
+
+            // Horizontal tab
+            yield return new object[] { GetRepeatedChar(Convert.ToChar(10), 1) };
+            yield return new object[] { GetRepeatedChar(Convert.ToChar(10), 3) };
+
+            // Carriage return
+            yield return new object[] { GetRepeatedChar(Convert.ToChar(13), 1) };
+            yield return new object[] { GetRepeatedChar(Convert.ToChar(13), 3) };
+
+            // Space
+            yield return new object[] { GetRepeatedChar(Convert.ToChar(32), 1) };
+            yield return new object[] { GetRepeatedChar(Convert.ToChar(32), 3) };
+
+            string GetRepeatedChar(char charToInsert, int numberOfTimesToInsert) => new string(charToInsert, numberOfTimesToInsert);
+        }
+    }
+}

src/libraries/System.Memory/tests/Base64/Base64TestHelper.cs

@@ -44,6 +44,20 @@ public static class Base64TestHelper
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
         };
 
+        public static bool IsByteToBeIgnored(byte charByte)
+        {
+            switch (charByte)
+            {
+                case 9: // Line feed
+                case 10: // Horizontal tab
+                case 13: // Carriage return
+                case 32: // Space
+                    return true;
+                default:
+                    return false;
+            }
+        }
+
         public const byte EncodingPad = (byte)'=';      // '=', for padding
         public const sbyte InvalidByte = -1;            // Designating -1 for invalid bytes in the decoding map