diff --git a/test/array.cxx b/test/array.cxx
index 745581d..e6925ab 100644
--- a/test/array.cxx
+++ b/test/array.cxx
@@ -26,12 +26,14 @@
 # endif
 
 # define ARRAY_EMPTY (0, ())
+# define ARRAY_ONE (1, ())
 # define ARRAY (3, (0, 1, 2))
 # define ARRAY_LARGE (33, (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32))
 # define ARRAY_VERY_LARGE (64, (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63))
 
 // element access
 
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_ARRAY_ELEM(0, ARRAY_ONE)) == 1 END
 BEGIN BOOST_PP_ARRAY_ELEM(1, ARRAY) == 1 END
 BEGIN BOOST_PP_ARRAY_ELEM(2, (5, (0, 1, 2, 3, 4))) == 2 END
 BEGIN BOOST_PP_ARRAY_ELEM(28, ARRAY_LARGE) == 28 END
@@ -48,6 +50,7 @@ BEGIN BOOST_PP_ARRAY_SIZE((33, (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
 BEGIN BOOST_PP_ARRAY_SIZE(ARRAY_VERY_LARGE) == 64 END
 BEGIN BOOST_PP_ARRAY_SIZE((64, (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63))) == 64 END
 BEGIN BOOST_PP_ARRAY_SIZE(ARRAY_EMPTY) == 0 END
+BEGIN BOOST_PP_ARRAY_SIZE(ARRAY_ONE) == 1 END
 
 // enum
 
@@ -63,7 +66,7 @@ BEGIN BOOST_PP_VARIADIC_SIZE(BOOST_PP_ARRAY_ENUM((5, (0, 1, 2, 3, 4)))) == 5 END
 BEGIN BOOST_PP_VARIADIC_SIZE(BOOST_PP_ARRAY_ENUM(ARRAY_LARGE)) == 33 END
 BEGIN BOOST_PP_VARIADIC_SIZE(BOOST_PP_ARRAY_ENUM(ARRAY_VERY_LARGE)) == 64 END
 BEGIN BOOST_PP_VARIADIC_SIZE(BOOST_PP_ARRAY_ENUM((64, (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63)))) == 64 END
-BEGIN BOOST_PP_VARIADIC_SIZE(BOOST_PP_ARRAY_ENUM(ARRAY_EMPTY)) == 1 END
+BEGIN BOOST_PP_VARIADIC_SIZE(BOOST_PP_ARRAY_ENUM(ARRAY_ONE)) == 1 END
 
 # endif
 
@@ -74,9 +77,11 @@ BEGIN BOOST_PP_LIST_AT(BOOST_PP_ARRAY_TO_LIST((5, (0, 1, 2, 3, 4))), 4) == 4 END
 BEGIN BOOST_PP_LIST_AT(BOOST_PP_ARRAY_TO_LIST((33, (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32))), 26) == 26 END
 BEGIN BOOST_PP_LIST_AT(BOOST_PP_ARRAY_TO_LIST(ARRAY_VERY_LARGE), 60) == 60 END
 BEGIN BOOST_PP_LIST_SIZE(BOOST_PP_ARRAY_TO_LIST(ARRAY_EMPTY)) == 0 END
+BEGIN BOOST_PP_LIST_SIZE(BOOST_PP_ARRAY_TO_LIST(ARRAY_ONE)) == 1 END
 
 // to_seq
 
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_SEQ_ELEM(0, BOOST_PP_ARRAY_TO_SEQ(ARRAY_ONE))) == 1 END
 BEGIN BOOST_PP_SEQ_ELEM(0, BOOST_PP_ARRAY_TO_SEQ(ARRAY)) == 0 END
 BEGIN BOOST_PP_SEQ_ELEM(3, BOOST_PP_ARRAY_TO_SEQ((5, (0, 1, 2, 3, 4)))) == 3 END
 BEGIN BOOST_PP_SEQ_ELEM(17, BOOST_PP_ARRAY_TO_SEQ(ARRAY_LARGE)) == 17 END
@@ -86,6 +91,7 @@ BEGIN BOOST_PP_SEQ_ELEM(42, BOOST_PP_ARRAY_TO_SEQ((64, (0, 1, 2, 3, 4, 5, 6, 7,
 
 # if BOOST_PP_VARIADICS
 
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_TUPLE_ELEM(0, BOOST_PP_ARRAY_TO_TUPLE(ARRAY_ONE))) == 1 END
 BEGIN BOOST_PP_TUPLE_ELEM(2, BOOST_PP_ARRAY_TO_TUPLE(ARRAY)) == 2 END
 BEGIN BOOST_PP_TUPLE_ELEM(1, BOOST_PP_ARRAY_TO_TUPLE((5, (0, 1, 2, 3, 4)))) == 1 END
 BEGIN BOOST_PP_TUPLE_ELEM(26, BOOST_PP_ARRAY_TO_TUPLE(ARRAY_LARGE)) == 26 END
@@ -93,6 +99,7 @@ BEGIN BOOST_PP_TUPLE_ELEM(37, BOOST_PP_ARRAY_TO_TUPLE((64, (0, 1, 2, 3, 4, 5, 6,
 
 # else
 
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_TUPLE_ELEM(1, 0, BOOST_PP_ARRAY_TO_TUPLE(ARRAY_ONE))) == 1 END
 BEGIN BOOST_PP_TUPLE_ELEM(3, 2, BOOST_PP_ARRAY_TO_TUPLE(ARRAY)) == 2 END
 BEGIN BOOST_PP_TUPLE_ELEM(5, 1, BOOST_PP_ARRAY_TO_TUPLE((5, (0, 1, 2, 3, 4)))) == 1 END
 BEGIN BOOST_PP_TUPLE_ELEM(33, 26, BOOST_PP_ARRAY_TO_TUPLE(ARRAY_LARGE)) == 26 END
@@ -102,6 +109,7 @@ BEGIN BOOST_PP_TUPLE_ELEM(64, 37, BOOST_PP_ARRAY_TO_TUPLE((64, (0, 1, 2, 3, 4, 5
 
 // insert
 
+BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_INSERT(ARRAY_ONE,0,63)) == 63 END
 BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_INSERT(ARRAY,2,40)) == 0 END
 BEGIN BOOST_PP_ARRAY_ELEM(1, BOOST_PP_ARRAY_INSERT(ARRAY,1,40)) == 40 END
 BEGIN BOOST_PP_ARRAY_ELEM(2, BOOST_PP_ARRAY_INSERT(ARRAY,1,40)) == 1 END
@@ -136,21 +144,26 @@ BEGIN BOOST_PP_ARRAY_ELEM(55, BOOST_PP_ARRAY_POP_FRONT(ARRAY_VERY_LARGE)) == 56
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_PUSH_BACK(ARRAY, 3)) == 4 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_PUSH_BACK(ARRAY_LARGE, 33)) == 34 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_PUSH_BACK(ARRAY_EMPTY, 10)) == 1 END
+BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_PUSH_BACK(ARRAY_ONE, 44)) == 2 END
 BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_PUSH_BACK(ARRAY, 3)) == 0 END
 BEGIN BOOST_PP_ARRAY_ELEM(33, BOOST_PP_ARRAY_PUSH_BACK(ARRAY_LARGE, 33)) == 33 END
 BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_PUSH_BACK(ARRAY_EMPTY, 136)) == 136 END
+BEGIN BOOST_PP_ARRAY_ELEM(1, BOOST_PP_ARRAY_PUSH_BACK(ARRAY_ONE, 245)) == 245 END
 
 // push_front
 
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_PUSH_FRONT(ARRAY, 555)) == 4 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_PUSH_FRONT(ARRAY_LARGE, 666)) == 34 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_PUSH_FRONT(ARRAY_EMPTY, 10)) == 1 END
+BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_PUSH_FRONT(ARRAY_ONE, 131)) == 2 END
 BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_PUSH_FRONT(ARRAY, 555)) == 555 END
 BEGIN BOOST_PP_ARRAY_ELEM(33, BOOST_PP_ARRAY_PUSH_FRONT(ARRAY_LARGE, 33)) == 32 END
 BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_PUSH_FRONT(ARRAY_EMPTY, 136)) == 136 END
+BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_PUSH_FRONT(ARRAY_ONE, 56)) == 56 END
 
 // remove
 
+BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REMOVE(ARRAY_ONE, 0)) == 0 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REMOVE(ARRAY, 1)) == 2 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REMOVE(ARRAY_LARGE, 17)) == 32 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REMOVE(ARRAY_VERY_LARGE, 27)) == 63 END
@@ -160,7 +173,9 @@ BEGIN BOOST_PP_ARRAY_ELEM(62, BOOST_PP_ARRAY_REMOVE(ARRAY_VERY_LARGE, 48)) == 63
 
 // replace
 
+BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REPLACE(ARRAY_ONE, 0, 3)) == 1 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REPLACE(ARRAY_VERY_LARGE, 27, 1000)) == 64 END
+BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_REPLACE(ARRAY_ONE, 0, 68)) == 68 END
 BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_REPLACE(ARRAY, 1, 44)) == 0 END
 BEGIN BOOST_PP_ARRAY_ELEM(29, BOOST_PP_ARRAY_REPLACE(ARRAY_LARGE, 29, 999)) == 999 END
 BEGIN BOOST_PP_ARRAY_ELEM(38, BOOST_PP_ARRAY_REPLACE(ARRAY_VERY_LARGE, 37, 1)) == 38 END
@@ -169,7 +184,9 @@ BEGIN BOOST_PP_ARRAY_ELEM(28, BOOST_PP_ARRAY_REPLACE(ARRAY_VERY_LARGE, 28, 1)) =
 // reverse
 
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REVERSE(ARRAY_VERY_LARGE)) == 64 END
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_REVERSE(ARRAY_ONE))) == 1 END
 BEGIN BOOST_PP_ARRAY_ELEM(0, BOOST_PP_ARRAY_REVERSE(ARRAY)) == 2 END
 BEGIN BOOST_PP_ARRAY_ELEM(29, BOOST_PP_ARRAY_REVERSE(ARRAY_LARGE)) == 3 END
 BEGIN BOOST_PP_ARRAY_ELEM(38, BOOST_PP_ARRAY_REVERSE(ARRAY_VERY_LARGE)) == 25 END
 BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REVERSE(ARRAY_EMPTY)) == 0 END
+BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_ARRAY_REVERSE(ARRAY_ONE)) == 1 END
diff --git a/test/seq.cxx b/test/seq.cxx
index ae37291..bcda829 100644
--- a/test/seq.cxx
+++ b/test/seq.cxx
@@ -13,6 +13,7 @@
 #
 # include <boost/preprocessor/arithmetic/add.hpp>
 # include <boost/preprocessor/arithmetic/sub.hpp>
+# include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/comparison/equal.hpp>
 # include <boost/preprocessor/comparison/less.hpp>
 # include <boost/preprocessor/control/iif.hpp>
@@ -25,6 +26,7 @@
 # include <boost/preprocessor/list/at.hpp>
 # include <boost/preprocessor/list/size.hpp>
 # include <boost/preprocessor/variadic/elem.hpp>
+# include <boost/preprocessor/variadic/size.hpp>
 # include <libs/preprocessor/test/test.h>
 
 # define SEQ_NONE ()
@@ -34,21 +36,30 @@
 # define REVERSAL(s, x, y) BOOST_PP_SUB(y, x)
 # define SUB_S(s, x, y) BOOST_PP_SUB(x, y)
 # define ADD_S(s, x, y) BOOST_PP_ADD(x, y)
+# define CAT_S(s, x, y) BOOST_PP_CAT(x, BOOST_PP_IS_EMPTY(y))
 
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_SEQ_HEAD(SEQ_NONE)) == 1 END
 BEGIN BOOST_PP_SEQ_HEAD(SEQ) == 4 END
 
+BEGIN BOOST_PP_SEQ_FOLD_LEFT(CAT_S, 1, SEQ_NONE) == 11 END
 BEGIN BOOST_PP_SEQ_FOLD_LEFT(SUB_S, 22, SEQ) == 10 END
+BEGIN BOOST_PP_SEQ_FOLD_RIGHT(CAT_S, 2, SEQ_NONE) == 21 END
 BEGIN BOOST_PP_SEQ_FOLD_RIGHT(ADD_S, 0, SEQ) == 12 END
 BEGIN BOOST_PP_SEQ_FOLD_RIGHT(REVERSAL, 0, SEQ) == 4 END
 
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REVERSE(SEQ_NONE))) == 1 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REVERSE(SEQ)) == 2514 END
 
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REST_N(2, SEQ)) == 52 END
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_FIRST_N(1, SEQ_NONE))) == 1 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_FIRST_N(2, SEQ)) == 41 END
 
+BEGIN BOOST_PP_IS_EMPTY(BOOST_PP_SEQ_ELEM(0, SEQ_NONE)) == 1 END
+BEGIN BOOST_PP_SEQ_SIZE(SEQ_NONE) == 1 END
 BEGIN BOOST_PP_SEQ_ELEM(2, SEQ) == 5 END
 BEGIN BOOST_PP_SEQ_SIZE(SEQ) == 4 END
 
+BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_TRANSFORM(CAT_S, 13, SEQ_NONE)) == 131 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_TRANSFORM(ADD_S, 2, SEQ)) == 6374 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_TAIL(SEQ) SEQ) == 1524152 END
 
@@ -74,6 +85,7 @@ BEGIN BOOST_PP_ARRAY_SIZE(BOOST_PP_SEQ_TO_ARRAY(SEQ_NONE)) == 1 END
 # define LESS_S(s, x, y) BOOST_PP_LESS(x, y)
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_FILTER(LESS_S, 3, SEQ)) == 45 END
 
+BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_INSERT(SEQ_NONE, 0, 7)) == 7 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_INSERT(SEQ, 0, 3)) == 34152 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_INSERT(SEQ, 2, 3)) == 41352 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_INSERT(SEQ, 4, 3)) == 41523 END
@@ -81,13 +93,16 @@ BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_INSERT(SEQ, 4, 3)) == 41523 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_POP_BACK(SEQ)) == 415 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_POP_FRONT(SEQ)) == 152 END
 
+BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_PUSH_FRONT(SEQ_NONE, 145))  == 145 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_PUSH_FRONT(SEQ, 3))  == 34152 END
+BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_PUSH_BACK(SEQ_NONE, 79))  == 79 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_PUSH_BACK(SEQ, 3))  == 41523 END
 
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REMOVE(SEQ, 0))  == 152 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REMOVE(SEQ, 2))  == 412 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REMOVE(SEQ, 3))  == 415 END
 
+BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REPLACE(SEQ_NONE, 0, 22))  == 22 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REPLACE(SEQ, 0, 3))  == 3152 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REPLACE(SEQ, 1, 3))  == 4352 END
 BEGIN BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_REPLACE(SEQ, 3, 3))  == 4153 END
@@ -119,6 +134,7 @@ BEGIN BOOST_PP_LIST_SIZE(BOOST_PP_SEQ_TO_LIST(SEQ_NONE)) == 1 END
 
 #if BOOST_PP_VARIADICS
 
+BEGIN BOOST_PP_VARIADIC_SIZE(BOOST_PP_SEQ_ENUM(SEQ_NONE)) == 1 END
 BEGIN BOOST_PP_VARIADIC_ELEM(0,BOOST_PP_SEQ_ENUM(SEQ)) == 4 END
 BEGIN BOOST_PP_TUPLE_ELEM(2,BOOST_PP_SEQ_ELEM(0,BOOST_PP_VARIADIC_SEQ_TO_SEQ(SEQVAR))) == 8 END