isolated modification_time/2 tests

tests/plunit/irrelevance_common.plt

@@ -129,16 +129,30 @@ test(item_base_name_semidet) :-
     semidet_for_file(item_base_name/2).
 
 
+%  modification_time(+File,-Time) is semidet.
+test(modification_time_semidet_true, 
+     [forall(theory_bg:modification_time(FileId, ExpectedTime)),
+      true(Time == ExpectedTime)
+     ]) :- modification_time(FileId, Time).
+test(modification_time_semidet_false, 
+     [forall(theory_bg:item_false(UnknownId)), fail]) :- 
+  modification_time(UnknownId, _Time).
+     
+%  modification_time(+Directory, -Size) fails
+test(modification_time_fails_for_directory, 
+     [forall(theory_bg:file_false(DirId)), fail]) :-
+  modification_time(DirId, _Time).
+
+  
+  
 %  access_time(+Item,-Time) is semidet.
 %  change_time(+Item,-Time) is semidet.
 %  creation_time(+Item,-Time) is semidet.
-%  modification_time(+Item,-Time) is semidet.
 test(time_semibound, forall(
                         ( member(TimePred, [
                                             access_time,
                                             change_time,
-                                            creation_time,
-                                            modification_time
+                                            creation_time
                                         ]),
                           call(theory_bg:TimePred,TrueItemId,TrueTime)
                         )
@@ -154,7 +168,6 @@ 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(other_time_semidet, forall(member(TimePred, [ 
                                                 access_time,
                                                 change_time,
@@ -163,11 +176,6 @@ test(other_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).
     
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