Add roundtrip tests for EncoderNLS and DecoderNLS (dotnet/corefx#34610)

This increases code coverage for System.Text.Encoding.Codepages from
68.9% to 74.5%.

Commit migrated from https://github.com/dotnet/corefx/commit/4febb444f82cabed2b3df186bcc8e9ad0b31dbf9

diff --git a/src/libraries/System.Text.Encoding.CodePages/tests/EncodingCodePages.cs b/src/libraries/System.Text.Encoding.CodePages/tests/EncodingCodePages.cs
index 84659255736a3b6fe6c7ef13cbf66a4511406bd1..d73034ced8bc5012c7d134ed5a7bdd3e5e4261c4 100644 (file)
--- a/src/libraries/System.Text.Encoding.CodePages/tests/EncodingCodePages.cs
+++ b/src/libraries/System.Text.Encoding.CodePages/tests/EncodingCodePages.cs
@@ -11,6 +11,9 @@ namespace System.Text.Tests
 {
     public partial class EncodingTest : IClassFixture<CultureSetup>
     {
+        private const string AsciiPrintable = " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+        private static readonly char[] s_asciiPrintableCharArr = AsciiPrintable.ToCharArray();
+
         public EncodingTest(CultureSetup setup)
         {
             // Setting up the culture happens externally, and only once, which is what we want.
@@ -447,7 +450,7 @@ namespace System.Text.Tests
             yield return Map(65000, "utf-7");
             yield return Map(65001, "utf-8");
         }
- 
+
         private static KeyValuePair<int, string> Map(int codePage, string webName)
         {
             return new KeyValuePair<int, string>(codePage, webName);
@@ -562,9 +565,42 @@ namespace System.Text.Tests
 
             // Small round-trip for ASCII alphanumeric range (some code pages use different punctuation!)
             // Start with space.
-            string asciiPrintable = " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
-            char[] traveled = encoding.GetChars(encoding.GetBytes(asciiPrintable));
-            Assert.Equal(asciiPrintable.ToCharArray(), traveled);
+            char[] traveled = encoding.GetChars(encoding.GetBytes(AsciiPrintable));
+            Assert.Equal(s_asciiPrintableCharArr, traveled);
+        }
+
+        [Theory]
+        [MemberData(nameof(CodePageInfo))]
+        public static void TestEncoderNLSAndDecoderNLSValidateDataRoundTrips(int codePage, string webName, string queryString)
+        {
+            Encoding encoding;
+
+            if (codePage != 20932 && codePage != 50222)
+            {
+                encoding = CodePagesEncodingProvider.Instance.GetEncoding(queryString);
+            }
+            else
+            {
+                encoding = CodePagesEncodingProvider.Instance.GetEncoding(codePage);
+            }
+
+            Encoder encoder = encoding.GetEncoder();
+            Decoder decoder = encoding.GetDecoder();
+
+            // Small round-trip for ASCII alphanumeric range (some code pages use different punctuation!)
+            // Start with space.
+            int asciiPrintableLength = s_asciiPrintableCharArr.Length;
+            int encodedByteCount = encoding.GetByteCount(s_asciiPrintableCharArr);
+            byte[] encodedBytes = new byte[encodedByteCount];
+            char[] decodedChars = new char[asciiPrintableLength];
+
+            int encodedLength = encoder.GetBytes(s_asciiPrintableCharArr, 0, asciiPrintableLength, encodedBytes, 0, false);
+            Assert.Equal(encodedByteCount, encodedLength);
+
+            int decodedLength = decoder.GetChars(encodedBytes, 0, encodedByteCount, decodedChars, 0);
+            Assert.Equal(asciiPrintableLength, decodedLength);
+
+            Assert.Equal(s_asciiPrintableCharArr, decodedChars);
         }
 
         [Theory]
@@ -600,7 +636,7 @@ namespace System.Text.Tests
         public static void TestRegister1252()
         {
             // This test case ensure we can map all 1252 codepage codepoints without any exception.
-            string s1252Result = 
+            string s1252Result =
             "\u0000\u0001\u0002\u0003\u0004\u0005\u0006\u0007\u0008\u0009\u000a\u000b\u000c\u000d\u000e\u000f" +
             "\u0010\u0011\u0012\u0013\u0014\u0015\u0016\u0017\u0018\u0019\u001a\u001b\u001c\u001d\u001e\u001f" +
             "\u0020\u0021\u0022\u0023\u0024\u0025\u0026\u0027\u0028\u0029\u002a\u002b\u002c\u002d\u002e\u002f" +
@@ -628,7 +664,6 @@ namespace System.Text.Tests
 
             Assert.Equal(s1252Result, win1252.GetString(enc));
         }
-
     }
 
     public class CultureSetup : IDisposable