BiPack: added @FixedSize for collection serialization

src/commonTest/kotlin/bipack/BipackEncoderTest.kt

@@ -5,7 +5,10 @@ import kotlinx.serialization.Serializable
 import net.sergeych.bintools.toDump
 import net.sergeych.bipack.*
 import kotlin.experimental.xor
-import kotlin.test.*
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
 
 @Serializable
 data class Foobar1N(val bar: Int, val foo: Int = 117)
@@ -114,7 +117,7 @@ class BipackEncoderTest {
         val u: UInt,
         @Unsigned
         val i: Int,
-        val k: UInt = 3u,
+        val k: Int = 3,
     )
 
     @Test
@@ -215,6 +218,28 @@ class BipackEncoderTest {
 //        println(d.decodeFromBipack<Types1>())
         assertEquals(t1, t2)
     }
+
+    @Serializable
+    data class Fixa(
+        @FixedSize(5)
+        val x: ByteArray
+    )
+
+    @Test
+    fun textFixed() {
+        val x = byteArrayOf(1,2,3,4,5)
+        //@Fixed(32)
+        val y = Fixa(byteArrayOf(1,2,3,4,5))
+        val d1 = BipackEncoder.encode(x)
+        println(d1.toDump())
+        assertEquals(6, d1.size)
+        val d2 = BipackEncoder.encode(y)
+        println(d2.toDump())
+        assertEquals(5, d2.size)
+        assertContentEquals(x, BipackDecoder.decode<ByteArray>(d1))
+        assertContentEquals(x, BipackDecoder.decode<Fixa>(d2).x)
+    }
+
 //    @Test
     @Test
     fun testMaps() {