diff --git a/build.gradle.kts b/build.gradle.kts
index 4c08e89..c48ddb9 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -17,6 +17,12 @@ kotlin {
     }
     linuxX64()
 
+    sourceSets {
+        commonTest.dependencies {
+            implementation(libs.test)
+        }
+    }
+
     compilerOptions {
         freeCompilerArgs.add("-opt-in=kotlin.ExperimentalUnsignedTypes")
     }
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index bb704f3..7b812f8 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -3,3 +3,6 @@ kotlin = "2.1.20"
 
 [plugins]
 multiplatform = { id = "org.jetbrains.kotlin.multiplatform", version.ref = "kotlin" }
+
+[libraries]
+test = { module = "org.jetbrains.kotlin:kotlin-test", version.ref = "kotlin" }
diff --git a/src/commonTest/kotlin/com/infendro/bytearray/ByteArray.kt b/src/commonTest/kotlin/com/infendro/bytearray/ByteArray.kt
new file mode 100644
index 0000000..16c479b
--- /dev/null
+++ b/src/commonTest/kotlin/com/infendro/bytearray/ByteArray.kt
@@ -0,0 +1,87 @@
+package com.infendro.bytearray
+
+import com.infendro.bytearray.ByteOrder.LITTLE_ENDIAN
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertFails
+
+class `ByteArray Test` {
+    @Test
+    fun `and() - size`() {
+        assertFails {
+            byteArrayOf() and byteArrayOf(0x00)
+        }
+        assertFails {
+            byteArrayOf(0x00) and byteArrayOf()
+        }
+    }
+
+    @Test
+    fun `padStart()`() {
+        val padded = byteArrayOf(0x02, 0x02).padStart(8, 0x01)
+        assertEquals(8, padded.size)
+        assertContentEquals(
+            byteArrayOf(0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x02, 0x02),
+            padded
+        )
+    }
+
+    @Test
+    fun `padEnd()`() {
+        val padded = byteArrayOf(0x02, 0x02).padEnd(8, 0x01)
+        assertEquals(8, padded.size)
+        assertContentEquals(
+            byteArrayOf(0x02, 0x02, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01),
+            padded
+        )
+    }
+
+    @Test
+    fun `toInt()`() {
+        assertEquals(
+            0x12345678,
+            byteArrayOf(0x12, 0x34, 0x56, 0x78).toInt()
+        )
+        assertEquals(
+            0x12345678,
+            byteArrayOf(0x78, 0x56, 0x34, 0x12).toInt(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toLong()`() {
+        assertEquals(
+            0x1234567812345678L,
+            byteArrayOf(0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78).toLong()
+        )
+        assertEquals(
+            0x1234567812345678L,
+            byteArrayOf(0x78, 0x56, 0x34, 0x12, 0x78, 0x56, 0x34, 0x12).toLong(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toUInt()`() {
+        assertEquals(
+            0x12345678U,
+            byteArrayOf(0x12, 0x34, 0x56, 0x78).toUInt()
+        )
+        assertEquals(
+            0x12345678U,
+            byteArrayOf(0x78, 0x56, 0x34, 0x12).toUInt(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toULong()`() {
+        assertEquals(
+            0x1234567812345678UL,
+            byteArrayOf(0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78).toULong()
+        )
+        assertEquals(
+            0x1234567812345678UL,
+            byteArrayOf(0x78, 0x56, 0x34, 0x12, 0x78, 0x56, 0x34, 0x12).toULong(LITTLE_ENDIAN)
+        )
+    }
+}
diff --git a/src/commonTest/kotlin/com/infendro/bytearray/Int.kt b/src/commonTest/kotlin/com/infendro/bytearray/Int.kt
new file mode 100644
index 0000000..356b847
--- /dev/null
+++ b/src/commonTest/kotlin/com/infendro/bytearray/Int.kt
@@ -0,0 +1,31 @@
+package com.infendro.bytearray
+
+import com.infendro.bytearray.ByteOrder.LITTLE_ENDIAN
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+
+class `Int Test` {
+    @Test
+    fun `toByteArray()`() {
+        assertContentEquals(
+            byteArrayOf(0x12, 0x34, 0x56, 0x78),
+            0x12345678.toByteArray()
+        )
+        assertContentEquals(
+            byteArrayOf(0x78, 0x56, 0x34, 0x12),
+            0x12345678.toByteArray(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toUByteArray()`() {
+        assertContentEquals(
+            ubyteArrayOf(0x12U, 0x34U, 0x56U, 0x78U),
+            0x12345678.toUByteArray()
+        )
+        assertContentEquals(
+            ubyteArrayOf(0x78U, 0x56U, 0x34U, 0x12U),
+            0x12345678.toUByteArray(LITTLE_ENDIAN)
+        )
+    }
+}
diff --git a/src/commonTest/kotlin/com/infendro/bytearray/Long.kt b/src/commonTest/kotlin/com/infendro/bytearray/Long.kt
new file mode 100644
index 0000000..0cba1b4
--- /dev/null
+++ b/src/commonTest/kotlin/com/infendro/bytearray/Long.kt
@@ -0,0 +1,31 @@
+package com.infendro.bytearray
+
+import com.infendro.bytearray.ByteOrder.LITTLE_ENDIAN
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+
+class `Long Test` {
+    @Test
+    fun `toByteArray()`() {
+        assertContentEquals(
+            byteArrayOf(0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78),
+            0x1234567812345678L.toByteArray()
+        )
+        assertContentEquals(
+            byteArrayOf(0x78, 0x56, 0x34, 0x12, 0x78, 0x56, 0x34, 0x12),
+            0x1234567812345678L.toByteArray(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toUByteArray()`() {
+        assertContentEquals(
+            ubyteArrayOf(0x12U, 0x34U, 0x56U, 0x78U, 0x12U, 0x34U, 0x56U, 0x78U),
+            0x1234567812345678L.toUByteArray()
+        )
+        assertContentEquals(
+            ubyteArrayOf(0x78U, 0x56U, 0x34U, 0x12U, 0x78U, 0x56U, 0x34U, 0x12U),
+            0x1234567812345678L.toUByteArray(LITTLE_ENDIAN)
+        )
+    }
+}
diff --git a/src/commonTest/kotlin/com/infendro/bytearray/UByteArray.kt b/src/commonTest/kotlin/com/infendro/bytearray/UByteArray.kt
new file mode 100644
index 0000000..4eee00b
--- /dev/null
+++ b/src/commonTest/kotlin/com/infendro/bytearray/UByteArray.kt
@@ -0,0 +1,87 @@
+package com.infendro.bytearray
+
+import com.infendro.bytearray.ByteOrder.LITTLE_ENDIAN
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertFails
+
+class `UByteArray Test` {
+    @Test
+    fun `and() - size`() {
+        assertFails {
+            ubyteArrayOf() and ubyteArrayOf(0x00U)
+        }
+        assertFails {
+            ubyteArrayOf(0x00U) and ubyteArrayOf()
+        }
+    }
+
+    @Test
+    fun `padStart()`() {
+        val padded = ubyteArrayOf(0x02U, 0x02U).padStart(8, 0x01U)
+        assertEquals(8, padded.size)
+        assertContentEquals(
+            ubyteArrayOf(0x01U, 0x01U, 0x01U, 0x01U, 0x01U, 0x01U, 0x02U, 0x02U),
+            padded
+        )
+    }
+
+    @Test
+    fun `padEnd()`() {
+        val padded = ubyteArrayOf(0x02U, 0x02U).padEnd(8, 0x01U)
+        assertEquals(8, padded.size)
+        assertContentEquals(
+            ubyteArrayOf(0x02U, 0x02U, 0x01U, 0x01U, 0x01U, 0x01U, 0x01U, 0x01U),
+            padded
+        )
+    }
+
+    @Test
+    fun `toInt()`() {
+        assertEquals(
+            0x12345678,
+            ubyteArrayOf(0x12U, 0x34U, 0x56U, 0x78U).toInt()
+        )
+        assertEquals(
+            0x12345678,
+            ubyteArrayOf(0x78U, 0x56U, 0x34U, 0x12U).toInt(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toLong()`() {
+        assertEquals(
+            0x1234567812345678L,
+            ubyteArrayOf(0x12U, 0x34U, 0x56U, 0x78U, 0x12U, 0x34U, 0x56U, 0x78U).toLong()
+        )
+        assertEquals(
+            0x1234567812345678L,
+            ubyteArrayOf(0x78U, 0x56U, 0x34U, 0x12U, 0x78U, 0x56U, 0x34U, 0x12U).toLong(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toUInt()`() {
+        assertEquals(
+            0x12345678U,
+            ubyteArrayOf(0x12U, 0x34U, 0x56U, 0x78U).toUInt()
+        )
+        assertEquals(
+            0x12345678U,
+            ubyteArrayOf(0x78U, 0x56U, 0x34U, 0x12U).toUInt(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toULong()`() {
+        assertEquals(
+            0x1234567812345678UL,
+            ubyteArrayOf(0x12U, 0x34U, 0x56U, 0x78U, 0x12U, 0x34U, 0x56U, 0x78U).toULong()
+        )
+        assertEquals(
+            0x1234567812345678UL,
+            ubyteArrayOf(0x78U, 0x56U, 0x34U, 0x12U, 0x78U, 0x56U, 0x34U, 0x12U).toULong(LITTLE_ENDIAN)
+        )
+    }
+}
diff --git a/src/commonTest/kotlin/com/infendro/bytearray/UInt.kt b/src/commonTest/kotlin/com/infendro/bytearray/UInt.kt
new file mode 100644
index 0000000..cfdd28f
--- /dev/null
+++ b/src/commonTest/kotlin/com/infendro/bytearray/UInt.kt
@@ -0,0 +1,31 @@
+package com.infendro.bytearray
+
+import com.infendro.bytearray.ByteOrder.LITTLE_ENDIAN
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+
+class `UInt Test` {
+    @Test
+    fun `toByteArray()`() {
+        assertContentEquals(
+            byteArrayOf(0x12, 0x34, 0x56, 0x78),
+            0x12345678U.toByteArray()
+        )
+        assertContentEquals(
+            byteArrayOf(0x78, 0x56, 0x34, 0x12),
+            0x12345678U.toByteArray(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toUByteArray()`() {
+        assertContentEquals(
+            ubyteArrayOf(0x12U, 0x34U, 0x56U, 0x78U),
+            0x12345678U.toUByteArray()
+        )
+        assertContentEquals(
+            ubyteArrayOf(0x78U, 0x56U, 0x34U, 0x12U),
+            0x12345678U.toUByteArray(LITTLE_ENDIAN)
+        )
+    }
+}
diff --git a/src/commonTest/kotlin/com/infendro/bytearray/ULong.kt b/src/commonTest/kotlin/com/infendro/bytearray/ULong.kt
new file mode 100644
index 0000000..e3e50f4
--- /dev/null
+++ b/src/commonTest/kotlin/com/infendro/bytearray/ULong.kt
@@ -0,0 +1,31 @@
+package com.infendro.bytearray
+
+import com.infendro.bytearray.ByteOrder.LITTLE_ENDIAN
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+
+class `ULong Test` {
+    @Test
+    fun `toByteArray()`() {
+        assertContentEquals(
+            byteArrayOf(0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78),
+            0x1234567812345678UL.toByteArray()
+        )
+        assertContentEquals(
+            byteArrayOf(0x78, 0x56, 0x34, 0x12, 0x78, 0x56, 0x34, 0x12),
+            0x1234567812345678UL.toByteArray(LITTLE_ENDIAN)
+        )
+    }
+
+    @Test
+    fun `toUByteArray()`() {
+        assertContentEquals(
+            ubyteArrayOf(0x12U, 0x34U, 0x56U, 0x78U, 0x12U, 0x34U, 0x56U, 0x78U),
+            0x1234567812345678UL.toUByteArray()
+        )
+        assertContentEquals(
+            ubyteArrayOf(0x78U, 0x56U, 0x34U, 0x12U, 0x78U, 0x56U, 0x34U, 0x12U),
+            0x1234567812345678UL.toUByteArray(LITTLE_ENDIAN)
+        )
+    }
+}