diff --git a/ostap/math/tests/test_math_valerrors.py b/ostap/math/tests/test_math_valerrors.py
new file mode 100644
index 00000000..e36eafd1
--- /dev/null
+++ b/ostap/math/tests/test_math_valerrors.py
@@ -0,0 +1,158 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# ============================================================================= 
+# Copyright (c) Ostap developpers.
+# ============================================================================= 
+## @file ostap/math/tests/test_math_valerrors.py
+#  Test module for the file ostap/utils/valerrors.py
+#
+#  - These objects are *NOT* for math!
+#  - The objects are used for graphs 
+#
+# ============================================================================= 
+""" Test module for ostap/utils/valerrors.py
+- These objects are *NOT* for math!
+"""
+# ============================================================================= 
+from   ostap.utils.valerrors import VE , VAE , VME, AE  
+import ostap.io.zipshelve    as     DBASE
+import pickle 
+# ============================================================================= 
+# logging 
+# =============================================================================
+from ostap.logger.logger import getLogger
+if '__main__' ==  __name__ : logger = getLogger ( 'test_math_valerros' ) 
+else                       : logger = getLogger ( __name__             )
+# ============================================================================= 
+
+# =============================================================================
+## test asymmetric errors:
+def test_asymerr () :
+
+    logger = getLogger( 'test_asymerr')
+    logger.info ( 'Test AsymErrors' )
+
+    
+    ae1 = AE ( -0.5 ,  1.0 )
+    ae2 = AE (  1.0 , -0.5 )
+    ae3 = AE (  0.5 ,  1.0 )
+
+    logger.info ( '%s %s %s' % ( ae1 , ae2 , ae3 ) )
+    
+    assert ae1 == ae2 , ' %s != %s ' % ( ae1 , ae2 )
+    assert ae1 == ae3 , ' %s != %s ' % ( ae1 , ae3 )
+    assert ae2 == ae3 , ' %s != %s ' % ( ae2 , ae3 )
+
+    ae1_  = pickle.loads ( pickle.dumps ( ae1 ) )
+    ae2_  = pickle.loads ( pickle.dumps ( ae2 ) )
+    ae3_  = pickle.loads ( pickle.dumps ( ae3 ) )
+
+    assert ae1_ == ae2 , ' %s != %s ' % ( ae1_ , ae2 )
+    assert ae1_ == ae3 , ' %s != %s ' % ( ae1_ , ae3 )
+    assert ae2_ == ae3 , ' %s != %s ' % ( ae2_ , ae3 )
+
+    
+# =============================================================================
+## test asymmetric errors:
+def test_valasymerr () :
+
+    logger = getLogger( 'test_valasymerr')
+    logger.info ( 'Test ValWithErrors' )
+
+    ae1 = VAE ( 1.0              , -0.5 ,  1.0 )
+    ae2 = VAE ( VE ( 1.0 , 0.0 ) , -0.5 ,  1.0 )
+    ae3 = VAE ( VE ( 1.0 , 0.0 ) , AE ( -0.5 , 1.0 ) )
+    
+    logger.info ( '%s %s %s' % ( ae1 , ae2 , ae3 ) )
+
+    assert ae1 == ae2 , ' %s != %s ' % ( ae1 , ae2 )
+    assert ae1 == ae3 , ' %s != %s ' % ( ae1 , ae3 )
+    assert ae2 == ae3 , ' %s != %s ' % ( ae2 , ae3 )
+
+    ae1_  = pickle.loads ( pickle.dumps ( ae1 ) )
+    ae2_  = pickle.loads ( pickle.dumps ( ae2 ) )
+    ae3_  = pickle.loads ( pickle.dumps ( ae3 ) )
+
+    assert ae1_ == ae2 , ' %s != %s ' % ( ae1_ , ae2 )
+    assert ae1_ == ae3 , ' %s != %s ' % ( ae1_ , ae3 )
+    assert ae2_ == ae3 , ' %s != %s ' % ( ae2_ , ae3 )
+
+    ## conversion to VE without bias 
+    ve1 = ae1.asVE ( bias = False ) 
+    ve2 = ae2.asVE ( bias = False ) 
+    ve3 = ae3.asVE ( bias = False ) 
+
+    logger.info ( 'asVE ( bias = False ) : %s %s %s' % ( ve1.toString ( '( %+-.3f +/- %-.3f )' ) ,
+                                                         ve2.toString ( '( %+-.3f +/- %-.3f )' ) ,
+                                                         ve3.toString ( '( %+-.3f +/- %-.3f )' ) ) )
+    
+    ## conversion to VE without bias 
+    ve1 = ae1.asVE ( bias = True ) 
+    ve2 = ae2.asVE ( bias = True ) 
+    ve3 = ae3.asVE ( bias = True ) 
+
+    logger.info ( 'asVE ( bias =  True ) : %s %s %s' % ( ve1.toString ( '( %+-.3f +/- %-.3f )' ) ,
+                                                         ve2.toString ( '( %+-.3f +/- %-.3f )' ) ,
+                                                         ve3.toString ( '( %+-.3f +/- %-.3f )' ) ) )
+    
+# =============================================================================
+## test multiple asymmetric errors:
+def test_valmulterr () :
+    
+    logger = getLogger( 'test_valmulterr')
+    logger.info ( 'Test ValWithMultiErrors' )
+
+    me1 = VME ( 1.0 ,     0.5 , 0.5   ,      -0.6 , 1.0   ,      0.7 , -0.3   ) 
+    me2 = VME ( 1.0 , AE( 0.5 , 0.5 ) , AE ( -0.6 , 1.0 ) , AE ( 0.7 , -0.3 ) ) 
+    me3 = VME ( VE ( 1 , 0.5 **2 )    , AE ( -0.6 , 1.0 ) , AE ( 0.7 , -0.3 ) ) 
+
+    ae1 = me1.asVAE()
+
+    logger.info ( '%s %s %s' % ( me1 , me2 , me3 ) )
+    
+    assert me1 == me2 , ' %s != %s ' % ( me1 , me2 )
+    assert me1 == me3 , ' %s != %s ' % ( me1 , me3 )
+    assert me2 == me3 , ' %s != %s ' % ( me2 , me3 )
+    
+    me1_  = pickle.loads ( pickle.dumps ( me1 ) )
+    me2_  = pickle.loads ( pickle.dumps ( me2 ) )
+    me3_  = pickle.loads ( pickle.dumps ( me3 ) )
+
+    assert me1_ == me2 , ' %s != %s ' % ( me1_ , me2 )
+    assert me1_ == me3 , ' %s != %s ' % ( me1_ , me3 )
+    assert me2_ == me3 , ' %s != %s ' % ( me2_ , me3 )
+
+    ae1 = me1.asVAE()
+    ae2 = me2.asVAE()
+    ae3 = me3.asVAE()
+    
+    logger.info ( 'as VAE                : %s %s %s' % ( ae1 , ae2 , ae3 ) )
+    
+    ## conversion to VE without bias 
+    ve1 = me1.asVE ( bias = False ) 
+    ve2 = me2.asVE ( bias = False ) 
+    ve3 = me3.asVE ( bias = False ) 
+
+    logger.info ( 'asVE ( bias = False ) : %s %s %s' % ( ve1.toString ( '( %+-.3f +/- %-.3f )' ) ,
+                                                         ve2.toString ( '( %+-.3f +/- %-.3f )' ) ,
+                                                         ve3.toString ( '( %+-.3f +/- %-.3f )' ) ) )
+    
+    ## conversion to VE without bias 
+    ve1 = me1.asVE ( bias = True ) 
+    ve2 = me2.asVE ( bias = True ) 
+    ve3 = me3.asVE ( bias = True ) 
+
+    logger.info ( 'asVE ( bias =  True ) : %s %s %s' % ( ve1.toString ( '( %+-.3f +/- %-.3f )' ) ,
+                                                         ve2.toString ( '( %+-.3f +/- %-.3f )' ) ,
+                                                         ve3.toString ( '( %+-.3f +/- %-.3f )' ) ) )
+
+# =============================================================================
+if '__main__' == __name__ :
+
+    test_asymerr    ()
+    test_valasymerr ()
+    test_valmulterr ()
+
+# =============================================================================
+##                                                                      The END 
+# =============================================================================