Add test

mirai-core/src/commonTest/kotlin/net.mamoe.mirai.utils.io/TypeConversionTest.kt

 package net.mamoe.mirai.utils.io
 
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.asserter
+
 
 class TypeConversionTest {
 
-    //@Test
+    @ExperimentalUnsignedTypes
+    @Test
     fun testConversions() {
-
+        assertEquals("01", byteArrayOf(1).toUHexString())
+        assertEquals("7F", byteArrayOf(0x7F).toUHexString())
+        assertEquals("FF", ubyteArrayOf(0xffu).toUHexString())
+        assertEquals("7F", ubyteArrayOf(0x7fu).toUHexString())
+        assertEquals(byteArrayOf(0, 0, 0, 0x01).toUHexString(), 1.toByteArray().toUHexString())
+        assertEquals(ubyteArrayOf(0x7fu, 0xffu, 0xffu, 0xffu).toByteArray().toUHexString(), Int.MAX_VALUE.toByteArray().toUHexString())
     }
 }
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