diff --git a/Object-Oriented Programming/Abstract Classes/Exercise 3/test/Tests.kt b/Object-Oriented Programming/Abstract Classes/Exercise 3/test/Tests.kt
index 174e9f33..2e7d4eb1 100644
--- a/Object-Oriented Programming/Abstract Classes/Exercise 3/test/Tests.kt	
+++ b/Object-Oriented Programming/Abstract Classes/Exercise 3/test/Tests.kt	
@@ -39,9 +39,7 @@ class TestAbstractClassesExercise3 {
         assertNoDeclaredMemberProperty()
       }
     }
-    loadToplevelFunction(loadFileFacade(packageName), "tune").apply {
-
-    }
+    loadToplevelFunction(loadFileFacade(packageName), "tune")
   }
 
   @Test
diff --git a/Object-Oriented Programming/Upcasting/Exercise 1/src/Task.kt b/Object-Oriented Programming/Upcasting/Exercise 1/src/Task.kt
index c79d7378..6005e99d 100644
--- a/Object-Oriented Programming/Upcasting/Exercise 1/src/Task.kt	
+++ b/Object-Oriented Programming/Upcasting/Exercise 1/src/Task.kt	
@@ -1,6 +1,8 @@
 // Upcasting/UpcastExercise1.kt
 package upcastingExercise1
 
+import atomictest.trace
+
 interface Rodent {
   fun eat(): String
   fun speak(): String
@@ -18,15 +20,22 @@ class KangarooRat: Rodent {
 }
 
 fun upcast(rodent: Rodent) {
-  println(rodent.eat())
-  println(rodent.speak())
+  trace(rodent.eat())
+  trace(rodent.speak())
 //   rodent.jump() // Won't compile
 }
 
 fun main() {
   val mouse = Mouse()
   val kangarooRat = KangarooRat()
-  println(kangarooRat.jump())
+  trace(kangarooRat.jump())
   upcast(mouse)
   upcast(kangarooRat)
+  trace eq """
+    KangarooRat.jump
+    Mouse.eat
+    Mouse.speak
+    KangarooRat.eat
+    KangarooRat.speak
+  """
 }
\ No newline at end of file
diff --git a/Object-Oriented Programming/Upcasting/Exercise 1/task-info.yaml b/Object-Oriented Programming/Upcasting/Exercise 1/task-info.yaml
index fe5e03f1..2d1f3da3 100644
--- a/Object-Oriented Programming/Upcasting/Exercise 1/task-info.yaml	
+++ b/Object-Oriented Programming/Upcasting/Exercise 1/task-info.yaml	
@@ -3,8 +3,8 @@ files:
 - name: src/Task.kt
   visible: true
   placeholders:
-  - offset: 405
-    length: 83
+  - offset: 430
+    length: 79
     placeholder_text: TODO()
 - name: test/Tests.kt
   visible: false
diff --git a/Object-Oriented Programming/Upcasting/Exercise 1/task.md b/Object-Oriented Programming/Upcasting/Exercise 1/task.md
index 92059856..850ec2ff 100644
--- a/Object-Oriented Programming/Upcasting/Exercise 1/task.md	
+++ b/Object-Oriented Programming/Upcasting/Exercise 1/task.md	
@@ -6,7 +6,7 @@ The starter code contains a `Rodent` interface and its two implementations:
 `jump()` function.
 
 Create a function `upcast(rodent: Rodent)` which displays the result of `eat()`
-and `speak()` using `println()`. Show that the compiler won't allow you to call
+and `speak()` using `trace()`. Show that the compiler won't allow you to call
 `jump()`.
 
 `main()` creates an instance of `Mouse` and `KangarooRat`, and shows that you
diff --git a/Object-Oriented Programming/Upcasting/Exercise 1/test/Tests.kt b/Object-Oriented Programming/Upcasting/Exercise 1/test/Tests.kt
index 5e9b5055..53126c7d 100644
--- a/Object-Oriented Programming/Upcasting/Exercise 1/test/Tests.kt	
+++ b/Object-Oriented Programming/Upcasting/Exercise 1/test/Tests.kt	
@@ -1,11 +1,68 @@
 package upcastingExercise1
 
+import atomictest.trace
+import org.junit.FixMethodOrder
 import org.junit.Test
-import util.unimplementedTest
+import org.junit.runners.MethodSorters
+import util.*
+import kotlin.reflect.KClass
+import kotlin.reflect.full.createInstance
+import kotlin.test.assertEquals
 
+@FixMethodOrder(MethodSorters.NAME_ASCENDING)
 class TestUpcastingExercise1 {
-    @Test fun testSolution() {
-        //TODO: implement your test here
-        unimplementedTest()
+
+  private val packageName = "upcastingExercise1"
+
+  private fun loadClass(className: String): KClass<*> = loadClass(packageName, className)
+
+  @Test
+  fun `#01 classes structure`() {
+    loadClass("Rodent").apply {
+      assertInterface()
+      assertDeclaredMemberFunction("eat")
+      assertDeclaredMemberFunction("speak")
     }
+
+    loadClass("Mouse").apply {
+      assertAbstract(expected = false)
+      assertInheritance("Rodent")
+      assertDeclaredMemberFunction("eat")
+      assertDeclaredMemberFunction("speak")
+    }
+
+    loadClass("KangarooRat").apply {
+      assertAbstract(expected = false)
+      assertInheritance("Rodent")
+      assertDeclaredMemberFunction("eat")
+      assertDeclaredMemberFunction("speak")
+      assertDeclaredMemberFunction("jump")
+    }
+
+    loadToplevelFunction(loadFileFacade(packageName), "upcast")
+  }
+
+  @Test
+  fun `#02 sofa operations`() {
+    val mouse = loadClass("Mouse").createInstance()
+    val kangarooRat = loadClass("KangarooRat").createInstance()
+    val upcast = loadToplevelFunction(loadFileFacade(packageName), "upcast")
+    val jump = loadClass("KangarooRat").assertDeclaredMemberFunction("jump")
+
+    trace(jump.call(kangarooRat))
+    upcast(null, mouse)
+    upcast(null, kangarooRat)
+
+    assertEquals(
+        message = "Incorrect sequence of actions of rodents",
+        actual = loadTraceContent(),
+        expected = listOf(
+            "KangarooRat.jump",
+            "Mouse.eat",
+            "Mouse.speak",
+            "KangarooRat.eat",
+            "KangarooRat.speak"
+        )
+    )
+  }
 }
\ No newline at end of file