  Nova shocks behave like scaled-down supernova remnant shocks with a lifetime
of only a few weeks or months, thereby providing a unique opportunity to study
the dynamics of non-relativistic shocks as well as the shock acceleration
physics. Recently, GeV and TeV gamma-ray emissions from an outburst of the
recurrent nova RS Ophiuchi have been observed. The light curves of the
gamma-ray emissions suggest that they arise from an external shock, which is
formed as the nova ejecta interacts with the ambient medium. The shock is
thought to transition from an adiabatic shock to a radiative one at later
times, but no such later observations are available for RS Ophiuchi. The
spectral evolution of the gamma-ray outburst of RS Ophiuchi was not well
measured, and hence the related particle acceleration mechanisms are not well
understood. T Coronae Borealis (T CrB) is another recurrent nova in Milky Way
and its last outburst was nearly ten times optically brighter than RS Ophiuchi.
Recently the optical light curve of T CrB displayed a state transition behavior
before the eruption, and it has been predicted that T CrB will undergo an
outburst in the near future. By performing a theoretical investigation, we find
that Fermi-LAT could probably capture the transition of the shock from the
adiabatic phase to the radiative phase at the GeV band if the ambient wind
medium is dense with $A_{\star}\geq1$. Due to its higher brightness, we also
find that imaging atmospheric Cherenkov telescopes such as MAGIC and VERITAS,
and extensive air shower experiments such as LHAASO could detect the nova
outburst and measure the gamma-ray spectrum in the very-high-energy
($>0.1\,{\rm TeV}$) band more precisely. This can be used to constrain the
high-energy cutoff index in the accelerated proton spectrum and the
acceleration efficiency, which will shed light on the particle acceleration
physics in nova shocks.
