A method for testing a device under test, the device under test being a measuring instrument to measure a physical parameter of a fluid, includes: performing a plurality of valid test runs, wherein a valid test run includes: exposing the device under test and a reference measuring instrument to the fluid under a set of influences, the set of influences being defined by influence parameters; monitoring the influence parameters; obtaining a reference value for the physical parameter from the reference measuring instrument; and obtaining a test value for the physical parameter from the device under test, wherein a test run is invalidated if influence parameters do not meet specified test requirements for the influence parameters; and then evaluating a plurality of test values originating from the plurality of valid test runs with respect to at least one of accuracy, repeatability and reproducibility.