feat(kotlin-collections): add list deep clone example and tests (#1181)

* feat(kotlin-collections): add list deep clone tests

* remove extraneous import

* update style and names

* add assertions

* add address `isNotSameAs` assertion

* reorder assertions

Author: husam-e

Diff for: core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com/baeldung/lists/ListCopyUnitTest.kt

@@ -18,4 +18,45 @@ class ListCopyUnitTest {
         assertThat(copied).isNotSameAs(cities)
         assertThat(copied[0]).isSameAs(cities[0])
     }
+
+    @Test
+    fun `should deep copy a data class with only primitive fields`() {
+        data class Person(var name: String, var age: Int)
+        val persons = listOf(Person("Bob", 20), Person("Alice", 21))
+        val personsCopy = persons.map { it.copy() }
+
+        assertThat(personsCopy).isNotSameAs(persons)
+        assertThat(personsCopy[0]).isNotSameAs(persons[0])
+        assertThat(persons[0].age).isEqualTo(personsCopy[0].age)
+
+        personsCopy[0].age = 22
+
+        assertThat(persons[0].age).isNotEqualTo(personsCopy[0].age)
+    }
+
+    @Test
+    fun `should deep copy a data class using a custom clone method`() {
+        data class Address(var streetName: String, var streetNumber: Int, var city: String)
+
+        data class Person(val name: String, val age: Int, val address: Address) {
+            fun clone(): Person {
+                return Person(this.name, this.age, this.address.copy())
+            }
+        }
+
+        val address1 = Address("Sesame Street", 1, "CartoonLand")
+        val address2 = Address("Sesame Street", 2, "CartoonLand")
+        val persons = listOf(Person("Bob", 20, address1), Person("Alice", 21, address2))
+
+        val personsCopy = persons.map { it.clone() }
+
+        assertThat(personsCopy).isNotSameAs(persons)
+        assertThat(personsCopy[0]).isNotSameAs(persons[0])
+        assertThat(personsCopy[0].address).isNotSameAs(persons[0].address)
+        assertThat(personsCopy[0].address).isEqualTo(persons[0].address)
+
+        personsCopy[0].address.streetNumber = 10
+
+        assertThat(personsCopy[0].address).isNotEqualTo(persons[0].address)
+    }
 }