Infrastructure: replaced 'untestable' with 'unimplemented test'

Introduction to Objects/Exceptions/Exercise 1/test/Tests.kt

@@ -4,7 +4,6 @@ import org.junit.Assert
 import org.junit.Test
 import util.TIMEOUT
 import util.runAndGetSystemOutput
-import util.untestable
 
 class TestExceptionsExercise1 {
   @Test(timeout = TIMEOUT)

Introduction to Objects/Packages/Exercise 1/test/Tests.kt

@@ -4,7 +4,6 @@ import org.junit.Assert
 import org.junit.Test
 import util.TIMEOUT
 import util.runAndGetSystemOutput
-import util.untestable
 import kotlin.math.E
 import kotlin.math.PI
 

Programming Basics/Data Types/Exercise 3/test/Tests.kt

@@ -5,7 +5,6 @@ import org.junit.FixMethodOrder
 import org.junit.Test
 import org.junit.runners.MethodSorters
 import util.TIMEOUT
-import util.untestable
 
 @FixMethodOrder(MethodSorters.NAME_ASCENDING)
 class TestDataTypesExercise3 {

Usability/Nullable Types/Exercise 2/test/Tests.kt

@@ -1,8 +1,10 @@
 package nullableTypesExercise2
 
 import org.junit.Test
-import util.untestable
+import util.unimplementedTest
 
 class TestNullableTypesExercise2 {
-    @Test fun testSolution() = untestable()
+    @Test fun testSolution() {
+        unimplementedTest()
+    }
 }

util/src/util.kt

@@ -533,10 +533,6 @@ private fun checkFunctionOrPropertyIsExtension(
       expectedReceiver.java == functionOrGetter.parameters.single().type)
 }
 
-fun untestable() {
-  Assert.assertTrue("No tests: tests always pass", true)
-}
-
 inline fun checkMainIsImplemented(main: () -> Unit) {
   try {
     main()