increase code coverage

Author: ThomasBreuer

lib/gslp.gi

@@ -93,23 +93,16 @@ InstallMethod( NrOutputsOfGeneralizedStraightLineProgram,
     local data;
 
     if IsStraightLineProgram( gslp ) then
-      data:= LinesOfStraightLineProgram( gslp );
-      data:= data[ Length( data ) ];
+      # The value is in general not set in the construction.
+      data:= Last( LinesOfStraightLineProgram( gslp ) );
       if ForAll( data, IsList ) then
         return Length( data );
       else
         return 1;
       fi;
     else
-      data:= DataOfGeneralizedStraightLineProgram( gslp );
-      if data[1] = "union" then
-        return Sum( List( data[2],
-                          NrOutputsOfGeneralizedStraightLineProgram ), 0 );
-      else
-        data:= data[2];
-        data:= data[ Length( data ) ];
-        return NrOutputsOfGeneralizedStraightLineProgram( data );
-      fi;
+      # The value should get set in the construction.
+      Error( "attribute value got lost?" );
     fi;
     end );
 
@@ -123,12 +116,8 @@ InstallMethod( ResultOfGeneralizedStraightLineProgram,
     function( gslp, gens )
     local data, result, prg;
 
-    if IsStraightLineProgram( gslp ) then
-      # This is necessary because the method for slps was installed
-      # before the implication from gslps increased the rank of the filter
-      # `IsStraightLineProgram'.
-      TryNextMethod();
-    fi;
+    # We may assume that the 'IsStraightLineProgram' method has higher rank.
+    Assert( 1, not IsStraightLineProgram( gslp ) );
 
     data:= DataOfGeneralizedStraightLineProgram( gslp );
     if data[1] = "union" then
@@ -185,21 +174,18 @@ InstallMethod( EquivalentStraightLineProgram,
 ##
 InstallMethod( ViewString,
     [ "IsGeneralizedStraightLineProgram" ],
-    function( gslp )
-    if IsStraightLineProgram( gslp ) then
-      TryNextMethod();
-    fi;
-    return "<generalized straight line program>";
-    end );
+    gslp -> "<generalized straight line program>" );
+
+InstallMethod( ViewString,
+    [ "IsStraightLineProgram" ],
+    slp -> "<straight line program>" );
+#T eventually move this to the GAP library
 
 InstallMethod( String,
     [ "IsGeneralizedStraightLineProgram" ],
     function( gslp )
     local data;
 
-    if IsStraightLineProgram( gslp ) then
-      TryNextMethod();
-    fi;
     data:= DataOfGeneralizedStraightLineProgram( gslp );
     return Concatenation( "GeneralizedStraightLineProgram( \"",
                data[1], "\", [ ",

tst/gslp.tst

@@ -0,0 +1,61 @@
+#@local prg, data
+############################################################################
+##
+#W  gslp.tst                   Utils Package                   Thomas Breuer
+##
+#Y  Copyright (C) 2026, The GAP Group
+##
+gap> START_TEST( "gslp.tst" );
+
+#
+gap> ReadPackage( "utils", "tst/loadall.g" );;
+gap> UtilsLoadingComplete;
+true
+
+# test inconsistent input for `GeneralizedStraightLineProgram`
+gap> GeneralizedStraightLineProgram( "union", [[[1,2]]], 1 );
+Error, usage: GeneralizedStraightLineProgram( <lines>[, <nrgens>] ) or General\
+izedStraightLineProgram( <kind>, <list> )
+gap> GeneralizedStraightLineProgram( "union", [] );
+Error, <list> must be a nonempty list
+gap> GeneralizedStraightLineProgram( "union",
+>        [ [ [[[1,2]]], 1 ], [ [[[1,3]]], 2 ] ] );
+Error, all entries of <list> must have the same input number
+gap> GeneralizedStraightLineProgram( "compose",
+>        [ [ [[[1,2]]], 1 ], [ [[[1,3]]], 2 ] ] );
+Error, inputs and outputs for <list> are not compatible
+gap> GeneralizedStraightLineProgram( "other", [[[1,2]]] );
+Error, <kind> must be one of "union", "compose"
+
+# test cases of `NrOutputsOfGeneralizedStraightLineProgram`
+gap> prg:= StraightLineProgram( [ [1,2,2,3], [3,-1] ], 2 );;
+gap> NrOutputsOfGeneralizedStraightLineProgram( prg );
+1
+
+# test `false` cases of `IsInternallyConsistent`
+gap> prg:= GeneralizedStraightLineProgram( "compose",
+>              [ [ [[[1,2]]], 1 ], [ [[[1,3]]], 1 ] ] );;
+gap> ResetFilterObj( prg, HasNrInputsOfGeneralizedStraightLineProgram );
+gap> SetNrInputsOfGeneralizedStraightLineProgram( prg, 3 );
+gap> IsInternallyConsistent( prg );
+false
+gap> data:= ShallowCopy( DataOfGeneralizedStraightLineProgram( prg ) );;
+gap> data[1]:= "other";;
+gap> ResetFilterObj( prg, HasDataOfGeneralizedStraightLineProgram );
+gap> SetDataOfGeneralizedStraightLineProgram( prg, data );
+gap> IsInternallyConsistent( prg );
+false
+
+# `ViewString` and `String`
+gap> ViewString( StraightLineProgram( [[[1,2]]], 1 ) );
+"<straight line program>"
+gap> ViewString( GeneralizedStraightLineProgram( "union", [ [[[1,2]]] ] ) );
+"<generalized straight line program>"
+gap> String( StraightLineProgram( [[[1,2]]], 1 ) );
+"StraightLineProgram( [ [ [ 1, 2 ] ] ], 1 )"
+gap> String( GeneralizedStraightLineProgram( "union", [ [[[1,2]]] ] ) );
+"GeneralizedStraightLineProgram( \"union\", [ StraightLineProgram( [ [ 1, 2 ] \
+], 1 ) ] )"
+
+#
+gap> STOP_TEST( "gslp.tst" );