TESTS: D3-mac Add tools for validating behavior

Created a test structure where emitted logs of a movie can be recorded
and validated on playback in ScummVM.

It's now possible to create a movie that calls scummVMLog with
interesting log lines by using a prepared Shared Cast (D3-mac-record).
Over on ScummVM the same movie can be played with a different Shared
Cast (D3-mac-replay). This replay shared cast will check if
the log emitted is identical to the log created on run.

README.md

@@ -9,4 +9,57 @@ Test for understanding event passing and script execution in D3 - Without a Shar
 Test for understanding event passing and script execution in D3 along with Macros - Without a SharedCast
 
 #### D4-mac/D4-Events-NonShared
-Test for understanding event passing and script execution in D4 - Without a SharedCast
+Test for understanding event passing and script execution in D4 - Without a SharedCast
+
+#### buildbot-tests/
+
+Tools for creating repeatable movies that can be run with Buildbot.
+
+An introduction.
+
+The Shared Cast in D3-mac-record has a macro called `scummVMLog`.
+Log things you're interested in by calling `scummVMLog importantVAR`.
+The macro stores this log as text in the cast B11.
+Save the movie after a run so that the text in cast B11 gets saved as well.
+B11 was used as to not interfere with regular casts.
+
+The Shared Cast in D3-mac-replay also has a macro called `scummVMLog`.
+This time it checks if the emitted log line is the same as the line stored in B11.
+It will emit a 'BUILDBOT: incorrect check for line: ...' when the emitted log
+is not the same as the stored log. 
+
+Since this all happens in Lingo lots of interesting things can by logging them.
+
+As an example check the movie putter in buildbot-tests/D3-mac. 
+
+For reference, the recorder and replay macros:
+-- scummVM logger
+macro scummVMLog logLine
+  global logText, nextLogLine
+  if logText = 0 then
+    set logText to logLine
+    set nextLogLine to 2
+  else
+    put logLine after line nextLogLine of logText
+    set nextLogLine to nextLogLine + 1
+  end if
+  put logText into cast B11
+
+-- scummVM check if log in cast B11 is the same
+macro scummVMLog logLine
+  global  currentLogLine
+  if currentLogLine = 0 then
+    -- globals were previously undefined
+    set currentLogLine to 1
+  else
+    set currentLogLine to currentLogLine + 1
+  end if
+  set lineToCheck to line currentLogLine of the text of cast B11
+  if lineToCheck = logLine then
+    put "Line is correct:" && currentLogLine
+  else
+    put "BUILDBOT: incorect check for line:" && currentLogLine
+    put "Got:" && logLine
+    put "Expected:" && lineToCheck
+  end if
+