implement tests

also fix MD5

src/commonTest/kotlin/com/infendro/hash/md/MD5.kt

@@ -0,0 +1,30 @@
+package com.infendro.hash.md
+
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+
+class `MD5 Test` {
+    val function = MD5
+
+    @Test
+    fun `bytes and block`() {
+        assertEquals(16, function.bytes)
+        assertEquals(128, function.bits)
+        assertEquals(64, function.block)
+    }
+
+    @Test
+    fun `empty bytearray`() {
+        val expected = ubyteArrayOf(
+            0xd4U, 0x1dU, 0x8cU, 0xd9U,
+            0x8fU, 0x00U, 0xb2U, 0x04U,
+            0xe9U, 0x80U, 0x09U, 0x98U,
+            0xecU, 0xf8U, 0x42U, 0x7eU,
+        )
+        val actual = function.hash(
+            ubyteArrayOf()
+        )
+        assertContentEquals(expected, actual)
+    }
+}