docs: update slides for lecture 18

lectures/revealjs/18-lecture-integration-testing.adoc

@@ -56,7 +56,7 @@ IT1901 Fall 2021 - {LECTURE_NO}
 - tests the complete system as it would be for actual use
 - complete system should comply with the requirements in the clients' environment
 
-== Testing pyramid
+== !
 
 image::../images/lecture18/test-pyramid.png[canvas, size=contain]
 
@@ -65,15 +65,15 @@ image::../images/lecture18/test-pyramid.png[canvas, size=contain]
 - as we go from the bottom towards the top the tests get more complex and resource intensive
 - the pyramid is a useful reminder that we should have many unit tests,  several integration tests and very few system and deployment tests 
 
-== System-Tiers-Layers-Modules-Components-Units
+== !
 
 image::../images/lecture18/system-units.png[canvas, size=contain]
 
-== Unit tests 
+== ! 
 
-image::../images/lecture18/system-units.png[canvas, size=contain]
+image::../images/lecture18/unit-tests.png[canvas, size=contain]
 
-== Integration tests 
+== ! 
 
 image::../images/lecture18/integration-tests.png[canvas, size=contain]
 
@@ -92,12 +92,12 @@ image::../images/lecture18/integration-tests.png[canvas, size=contain]
 - a simulated component is usually referred to as a mock, stub or fake  
 - when the simulated component is using / calling the tested component it is called a driver
   
-== Simulating parts 
+== ! 
 
 image::../images/lecture18/mocked-server.png[canvas, size=contain]
 
 
-== Simulating parts (2) 
+== ! 
 
 image::../images/lecture18/mocked-client.png[canvas, size=contain]