  Macrorealism is a classical world view asserting that the properties of
macro-objects exist independently and irrespective of observation. One
practical approach to test this view in quantum theory is to observe the
quantum coherence for macro-object in an interference experiment. An elegant
and conceptually appealing approach for testing the notion of macrorealism in
quantum theory is through the violation of Leggett-Garg inequality. However, a
conclusive Leggett-Garg test hinges on how the non-invasive measurability
criteria is guaranteed in an experiment and remains a debated issue till date.
In this work, we connect the practical and the conceptual approaches for
testing the macrorealism through the weak value. We argue that whenever quantum
effect is observed in an interference experiment there is an existence of
anomalous weak value. Further, we demonstrate that whenever such weak value
exists, one obtains the violation of a Leggett-Garg inequality in any
interference experiment. Since the system itself serves as apparatus in a
path-only interference experiment, one cannot salvage the macrorealism by
abandoning the non-invasive measurability assumption. We provide a rigorous
discussion about the assumptions involved in Leggett-Garg scenario and how our
scheme fits into it. Further, using the quasiprobability approach we explain
how non-invasive measurability condition is satisfied in our scheme.
