Fixed incomplete initialization for classes of nil, true, and false

The classes were not put into the globals dictionary and got loaded more than once, which lead to the classes being not equal to each other.
Signed-off-by: Stefan Marr <git@stefan-marr.de>

src/som/vm/universe.py

@@ -255,8 +255,13 @@ class Universe(object):
         self.blockClass = self.load_class(self.symbol_for("Block"))
 
         # Setup the true and false objects
-        self.trueObject  = self.new_instance(self.load_class(self.symbol_for("True")))
-        self.falseObject = self.new_instance(self.load_class(self.symbol_for("False")))
+        trueClassName    = self.symbol_for("True")
+        trueClass        = self.load_class(trueClassName)
+        self.trueObject  = self.new_instance(trueClass)
+        
+        falseClassName   = self.symbol_for("False")
+        falseClass       = self.load_class(falseClassName)
+        self.falseObject = self.new_instance(falseClass)
 
         # Load the system class and create an instance of it
         self.systemClass = self.load_class(self.symbol_for("System"))
@@ -269,6 +274,12 @@ class Universe(object):
         self.set_global(self.symbol_for("system"), system_object)
         self.set_global(self.symbol_for("System"), self.systemClass)
         self.set_global(self.symbol_for("Block"),  self.blockClass)
+        
+        self.set_global(self.symbol_for("Nil"),    self.nilClass)
+        
+        self.set_global( trueClassName,  trueClass)
+        self.set_global(falseClassName, falseClass)
+        
         return system_object
     
     def symbol_for(self, string):

tests/som_test.py

@@ -4,6 +4,7 @@ from som.vm.universe import Universe
 
 class SomTest(unittest.TestCase):
     @parameterized.expand([
+        ("ClassStructure",),
         ("Array"         ,),
         ("BigInteger"    ,),
         ("Block"         ,),