KTLN-533: Calling Private Functions of a Class from Outside the Class in Kotlin (#772)

* pom kotlin version

* pom version

* added unit tests

* fixed unit tests

* Fixed Unit test

Author: nappy29

core-kotlin-modules/core-kotlin-9/src/test/kotlin/com/baeldung/privateFunction/PrivateFunctionUnitTest.kt

@@ -0,0 +1,62 @@
+package com.baeldung.privateFunction
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+class PrivateFunctionUnitTest {
+
+    @Test
+    fun `Makes call to private method Using Reflection`() {
+        val obj = MyClass()
+        val privateMethod = MyClass::class.java.getDeclaredMethod("privateMethod")
+        privateMethod.isAccessible = true
+
+        val output = privateMethod.invoke(obj)
+
+        assertEquals("This is a private method", output)
+    }
+
+    @Test
+    fun `Makes call to private method Using Inner Class`() {
+        val obj = MyClassWithInnerClass()
+        val innerObj = obj.MyInnerClass()
+        val output = innerObj.callPrivateMethod()
+
+        assertEquals("This is a private method", output)
+    }
+
+    @Test
+    fun `Makes call to private method Using public method`() {
+        val obj = MyPublicClass()
+
+        assertEquals("This is a private method", obj.callPrivateMethod())
+    }
+}
+
+class MyClass {
+    private fun privateMethod(): String {
+        return "This is a private method"
+    }
+}
+
+class MyClassWithInnerClass {
+    private fun privateMethod(): String {
+        return "This is a private method"
+    }
+
+    inner class MyInnerClass {
+        fun callPrivateMethod(): String {
+           return privateMethod()
+        }
+    }
+}
+
+class MyPublicClass {
+    private fun privateMethod(): String {
+        return "This is a private method"
+    }
+
+    fun callPrivateMethod(): String {
+        return privateMethod()
+    }
+}