[commons-rng] 02/09: Add test for round trip of seeds from bytes to chars.

[ah...@apache.org]

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aherbert pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/commons-rng.git

commit d0033bbc16ec3421ae5aa62bbdeb958353064f1c
Author: aherbert <ah...@apache.org>
AuthorDate: Wed Oct 23 11:55:58 2019 +0100

    Add test for round trip of seeds from bytes to chars.
---
 .../commons/rng/examples/stress/HexTest.java       | 119 +++++++++++++++++++++
 1 file changed, 119 insertions(+)

diff --git a/commons-rng-examples/examples-stress/src/test/java/org/apache/commons/rng/examples/stress/HexTest.java b/commons-rng-examples/examples-stress/src/test/java/org/apache/commons/rng/examples/stress/HexTest.java
new file mode 100644
index 0000000..1fe5c58
--- /dev/null
+++ b/commons-rng-examples/examples-stress/src/test/java/org/apache/commons/rng/examples/stress/HexTest.java
@@ -0,0 +1,119 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.rng.examples.stress;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.Locale;
+import java.util.concurrent.ThreadLocalRandom;
+
+/**
+ * Tests for {@link Hex}.
+ */
+public class HexTest {
+    /** Upper-case hex digits. */
+    private static final char[] DIGITS = {
+        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
+    };
+
+    /**
+     * Test a round-trip hex encode and decode of a byte[] seed.
+     *
+     * <p>This test ensures that a generated byte[] seed recorded by the stress command
+     * in the results file can be used to create the same seed.
+     */
+    @Test
+    public void testHexEncodeAndDecode() {
+        // Empty bytes
+        for (int size = 0; size < 10; size++) {
+            assertHexEncodeAndDecode(new byte[size]);
+        }
+        // Random bytes
+        for (int size : new int[] {3, 4, 5, 8, 16, 31}) {
+            final byte[] bytes = new byte[size];
+            for (int i = 0; i < 5; i++) {
+                ThreadLocalRandom.current().nextBytes(bytes);
+                assertHexEncodeAndDecode(bytes);
+            }
+        }
+    }
+
+    /**
+     * Assert the bytes can be encoded and decoded.
+     *
+     * @param bytes the bytes
+     */
+    private static void assertHexEncodeAndDecode(byte[] bytes) {
+        // Use a StringBuilder to append the chars as this is the method used in the stress command.
+        final StringBuilder sb = new StringBuilder();
+        sb.append(Hex.encodeHex(bytes));
+        final byte[] decoded = Hex.decodeHex(sb);
+        Assert.assertArrayEquals(bytes, decoded);
+    }
+
+    /**
+     * Test a round-trip hex decode and encode of a char[] seed.
+     *
+     * <p>This test ensures that a user input random hex seed passed to the stress command
+     * can be converted to bytes and then recorded in the results file.
+     */
+    @Test
+    public void testHexDecodeAndEncode() {
+        // Note: char[] must be an even length.
+        // Empty chars.
+        for (int size = 0; size < 10; size++) {
+            final char[] chars = new char[size * 2];
+            Arrays.fill(chars, '0');
+            assertHexDecodeAndEncode(chars);
+        }
+        // Random bytes
+        for (int size : new int[] {3, 4, 5, 8, 16, 31}) {
+            final char[] chars = new char[size * 2];
+            for (int i = 0; i < 5; i++) {
+                // Encode upper case
+                for (int j = 0; j < chars.length; j++) {
+                    chars[j] = DIGITS[ThreadLocalRandom.current().nextInt(16)];
+                }
+                assertHexDecodeAndEncode(chars);
+            }
+        }
+    }
+
+    /**
+     * Assert the characters can be decoded and encoded.
+     *
+     * @param chars the chars
+     */
+    private static void assertHexDecodeAndEncode(char[] chars) {
+        final String text = String.valueOf(chars);
+        final byte[] decoded = Hex.decodeHex(text);
+        // Test the encoding is lower case
+        Assert.assertArrayEquals(text.toLowerCase(Locale.US).toCharArray(), Hex.encodeHex(decoded));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testHexThrowsWithOddNumberOfCharacters() {
+        Hex.decodeHex("0");
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testHexThrowsWithIllegalHexCharacters() {
+        Hex.decodeHex("0g");
+    }
+}