We show on two examples, namely a calculation for charge symmetry breaking in
pn->d pi^0 that allows one to extract the quark mass difference induced part of
the proton--neutron mass difference and a high precision calculation for
pion--deuteron scattering and its implications for the value of the charged
pion--nucleon coupling constant, how QCD tests can be performed from low energy
hadronic observables.Comment: 9 pages; Invited talk at workshop CHIRAL'10, Valencia (Spain), June
21-24, 201
