Methods and systems of testing for a gas leak between an inlet zone and an outlet zone of a gas flow component in a shut state are provided. Different tracer and carrier gases are used. The carrier gas is circulated through the outlet zone of the gas flow component to purge the tracer gas from this outlet zone. A spectroscopic emission from the carrier gas indicative of an amount of the purged tracer gas is monitored. A test flow of the tracer gas is introduced in the inlet zone of the gas flow component, and the inlet pressure is increased for successive pressure increments. The presence of a gas leak is determined upon detecting an intensity step variation in the monitored spectroscopic emission following one of the pressure increments in the inlet pressure.