--- /dev/null	2020-03-24 13:27:56.000000000 -0700
+++ new/test/jdk/sun/nio/cs/mapping/TestConv.java	2020-03-24 13:27:55.000000000 -0700
@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 1999, 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/* @test
+   @bug 4179153 4652234 6529796
+   @summary Read code mapping table and check code conversion
+   @modules jdk.charsets
+ */
+
+import java.io.*;
+import java.nio.charset.Charset;
+import java.util.HashSet;
+
+public class TestConv {
+    static int errorNum = 0;
+    private static final int maxBytesPerChar = 10;
+
+    public static void main(String args[])
+        throws Exception
+    {
+        File d = new File(System.getProperty("test.src", "."));
+        if (args.length == 0) {
+            String[] files = d.list();
+            String encoding;
+            for (int i = 0; i < files.length; i++) {
+                if (files[i].endsWith(".b2c")) {
+                    encoding = files[i].substring(0, files[i].length() - 4 );
+                    check(d, encoding);
+                }
+            }
+        } else {
+            for (int i = 0; i < args.length; i++)
+                check(d, args[i]);
+        }
+    }
+
+    static class Parser2 extends CoderTest.Parser {
+        int warnOff;
+        String regwarnCP;
+        Parser2 (InputStream is) throws IOException {
+            super(is);
+        }
+        protected boolean isDirective(String line) {
+            if ((warnOff = line.indexOf("REGWARN")) != -1)
+                regwarnCP = line.substring(warnOff+7);
+            else
+                regwarnCP = null;
+            return false;
+        }
+    }
+
+    private static void check(File dir, String encoding) throws Exception
+    {
+        byte[] inByte;
+        byte[] outByte;
+        char[] inChar;
+        String inStr;
+        String outStr;
+
+        System.out.println("\nChecking " + encoding + "...");
+        errorNum = 0;
+
+        if (!Charset.isSupported(encoding)) {
+            System.out.println("Not supported: " + encoding);
+            return;
+        }
+
+        Parser2 p = null;
+        try {
+            p = new Parser2(new FileInputStream(new File(dir, encoding + ".b2c")));
+        } catch (Exception e) {
+            throw new Exception("Can't open file " + encoding + ".b2c");
+        }
+        CoderTest.Entry e = new CoderTest.Entry();
+
+        while ((e = (CoderTest.Entry)p.next(e)) != null) {
+            if (e.cp2 != 0)
+                continue;  // skip composite (base+cc) for now
+            inByte = e.bb;
+            inChar = Character.toChars(e.cp);
+            inStr = new String(inChar);
+            outStr = new String(inByte, encoding);
+            outByte = inStr.getBytes(encoding);
+            int r = compareInOut(inStr, outStr, inByte, outByte);
+            if (r == 1) {
+                if (p.warnOff == -1)
+                    errorNum++;
+                else {
+                   System.out.println ("Regression Warning code point " +
+                                       p.regwarnCP);
+                }
+                System.out.println("Warning " + errorNum
+                                   + ": " + byteString(inByte)
+                                   + " -> \\u" + toHex(outStr)
+                                   + "  multi-mapping? \\u" + toHex(inStr));
+            } else if (r == 2) {
+                if (p.warnOff == -1)
+                    errorNum++;
+            }
+        }
+
+        if (errorNum == 0) {
+            System.out.println("OK.");
+        } else {
+            throw new RuntimeException(errorNum + " Warning(s).");
+        }
+    }
+
+    private static int compareInOut(String inStr, String outStr,
+                                byte[] inByte, byte[] outByte)
+    {
+        if (inStr.compareTo(outStr) != 0)
+            return 1;
+
+        if (inByte.length != outByte.length) {
+            return 2;
+        }
+
+        for (int i = 0; i < inByte.length; i++) {
+            if (inByte[i] != outByte[i])
+                return 2;
+        }
+
+        return 0;
+    }
+
+    private static String toHex(String str)
+    {
+        if (str.length() == 0)
+            return "";
+        String s = Integer.toHexString(str.charAt(0)).toUpperCase();
+        if (s.length() == 1 || s.length() == 3)
+            return "0" + s;
+        return s;
+    }
+
+    private static String byteString(byte[] b)
+    {
+        String s = "0x";
+        for (int i = 0; i < b.length; i++)
+            s += Integer.toHexString(b[i] & 0xff).toUpperCase();
+        return s;
+    }
+
+}