fix exception in modification_time/2

add unit test

irrelevance_common.pl

@@ -134,7 +134,7 @@ change_time(Item,Time) :- theory_bg:item(Item, Dict), !,
 %
 %  Returns the modification time of the item.
 modification_time(Item,Time) :- theory_bg:item(Item, Dict), !,
-    Time=Dict.modification_time.
+    Time=Dict.get(modification_time).
 
 %!  access_time(++Item, -Timestamp) is semidet.
 %

tests/plunit/irrelevance_common.plt

@@ -49,10 +49,12 @@ test(abs_path_semidet) :-
 test(file_size_semibound, forall(theory_bg:file_size(TrueFileId,TrueSize))) :-
     first_bound(file_size/2, [TrueFileId, TrueSize]).
     
-%  file_fize(+File, -Size) det if file is known, false else
+%  file_size(+File, -Size) det if file is known, false else
 test(file_size_semidet) :-
     semidet_for_file(file_size/2).
 
+
+   
 %%
 %% directory/1
 %% 
@@ -153,7 +155,7 @@ test(creation_time_semidet) :-
 %  access_time(+File, -Time) det if file is known, false else
 %  change_time(+File, -Time) det if file is known, false else
 %  modification_time(+File, -Time) det if file is known, false else
-test(creation_time_semidet, forall(member(TimePred, [ 
+test(other_time_semidet, forall(member(TimePred, [ 
                                                 access_time,
                                                 change_time,
                                                 modification_time
@@ -162,6 +164,11 @@ test(creation_time_semidet, forall(member(TimePred, [
     semidet_for_file(TimePred/2).
 
 
+%  modification_time(+Directory, -Size) fails
+test(modification_time_fails_for_directory, 
+     [forall(theory_bg:file_false(DirId)), fail]) :-
+  modification_time(DirId, _Time).
+    
 %%
 %% newer/2
 %%