  We study the query complexity of testing for properties defined by read once
formulas, as instances of {\em massively parametrized properties}, and prove
several testability and non-testability results. First we prove the testability
of any property accepted by a Boolean read-once formula involving any bounded
arity gates, with a number of queries exponential in $\epsilon$, doubly
exponential in the arity, and independent of all other parameters. When the
gates are limited to being monotone, we prove that there is an {\em estimation}
algorithm, that outputs an approximation of the distance of the input from
satisfying the property. For formulas only involving And/Or gates, we provide a
more efficient test whose query complexity is only quasipolynomial in
$\epsilon$. On the other hand, we show that such testability results do not
hold in general for formulas over non-Boolean alphabets; specifically we
construct a property defined by a read-once arity $2$ (non-Boolean) formula
over an alphabet of size $4$, such that any $1/4$-test for it requires a number
of queries depending on the formula size. We also present such a formula over
an alphabet of size $5$ that additionally satisfies a strong monotonicity
condition.
