python/testData/inspections/PyStringFormatInspection/NewStyleMappingKeyWithSubscriptionDictArg.py

"{foo[a]}".format(foo={"a": 1})
<warning descr="Too few arguments for format string">"{foo[b]}"</warning>.format(foo={"a": 1})

"{foo[1]}".format(foo={1: 1})
<warning descr="Too few arguments for format string">"{foo[2]}"</warning>.format(foo={1: 1})