From c3ab8c3dd9abd50e79baa9e5966f4e6a75ee1cc5 Mon Sep 17 00:00:00 2001
From: Walter Oggioni <oggioni.walter@gmail.com>
Date: Sat, 24 Jul 2021 20:01:41 +0200
Subject: [PATCH] added test for Hash

---
 src/main/java/net/woggioni/jwo/hash/Hash.java | 32 +++++--------
 .../java/net/woggioni/jwo/hash/HashTest.java  | 45 +++++++++++++++++++
 2 files changed, 57 insertions(+), 20 deletions(-)
 create mode 100644 src/test/java/net/woggioni/jwo/hash/HashTest.java

diff --git a/src/main/java/net/woggioni/jwo/hash/Hash.java b/src/main/java/net/woggioni/jwo/hash/Hash.java
index e6627a6..9b6145b 100644
--- a/src/main/java/net/woggioni/jwo/hash/Hash.java
+++ b/src/main/java/net/woggioni/jwo/hash/Hash.java
@@ -1,12 +1,14 @@
 package net.woggioni.jwo.hash;
 
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 import lombok.SneakyThrows;
 
 import java.io.InputStream;
 import java.security.MessageDigest;
-import java.util.Arrays;
 
+@EqualsAndHashCode
 @RequiredArgsConstructor
 public class Hash {
 
@@ -22,26 +24,11 @@ public class Hash {
         private final String key;
     }
 
-    final Algorithm algorithm;
-    final byte[] bytes;
+    @Getter
+    private final Algorithm algorithm;
 
-    @Override
-    public boolean equals(Object other) {
-        if(other == null) return false;
-        else if(getClass() != other.getClass()) return false;
-        Hash otherHash = (Hash) other;
-        if(algorithm != otherHash.algorithm) return false;
-        return Arrays.equals(bytes, otherHash.bytes);
-    }
-
-    @Override
-    public int hashCode() {
-        int result = algorithm.hashCode();
-        for(byte b : bytes) {
-            result ^= b;
-        }
-        return result;
-    }
+    @Getter
+    private final byte[] bytes;
 
     @SneakyThrows
     public static Hash hash(Algorithm algo, InputStream is, byte[] buffer) {
@@ -83,4 +70,9 @@ public class Hash {
         }
         return new String(hexChars);
     }
+
+    @Override
+    public String toString() {
+        return bytesToHex(bytes);
+    }
 }
\ No newline at end of file
diff --git a/src/test/java/net/woggioni/jwo/hash/HashTest.java b/src/test/java/net/woggioni/jwo/hash/HashTest.java
new file mode 100644
index 0000000..30a9ea1
--- /dev/null
+++ b/src/test/java/net/woggioni/jwo/hash/HashTest.java
@@ -0,0 +1,45 @@
+package net.woggioni.jwo.hash;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.ByteArrayInputStream;
+import java.util.Random;
+
+public class HashTest {
+
+    private byte[] sample;
+
+    @BeforeEach
+    public void setup() {
+        sample = new byte[0x400];
+        Random random = new Random(0xdeadbeef);
+        random.nextBytes(sample);
+    }
+
+    @Test
+    public void checkHashIsRepeatableAndComparesCorrectly() {
+        byte[] buffer = new byte[0x1000];
+        Hash hash1 = Hash.md5(new ByteArrayInputStream(sample), buffer);
+        Hash hash2 = Hash.md5(new ByteArrayInputStream(sample), buffer);
+        Assertions.assertEquals(hash1.hashCode(), hash2.hashCode());
+        Assertions.assertEquals(hash1, hash2);
+        Assertions.assertEquals(hash1.toString(), hash2.toString());
+    }
+
+    @Test
+    public void checkReversingTheSampleGivesDifferentHash() {
+        byte[] reverseSample = new byte[sample.length];
+        for(int i = 0; i < sample.length; i++) {
+            reverseSample[reverseSample.length - i - 1] = sample[i];
+        }
+
+        byte[] buffer = new byte[0x1000];
+        Hash hash1 = Hash.md5(new ByteArrayInputStream(sample), buffer);
+        Hash hash2 = Hash.md5(new ByteArrayInputStream(reverseSample), buffer);
+        Assertions.assertNotEquals(hash1.hashCode(), hash2.hashCode());
+        Assertions.assertNotEquals(hash1, hash2);
+        Assertions.assertNotEquals(hash1.toString(), hash2.toString());
+    }
+}