  In the subgraph-freeness problem, we are given a constant-size graph $H$, and
wish to determine whether the network contains $H$ as a subgraph or not. The
\emph{property-testing} relaxation of the problem only requires us to
distinguish graphs that are $H$-free from graphs that are $\epsilon$-far from
$H$-free, meaning an $\epsilon$-fraction of their edges must be removed to
obtain an $H$-free graph. Recently, Censor-Hillel et. al. and Fraigniaud et al.
showed that in the property-testing regime it is possible to test $H$-freeness
for any graph $H$ of size 4 in constant time, $O(1/\epsilon^2)$ rounds,
regardless of the network size. However, Fraigniaud et. al. also showed that
their techniques for graphs $H$ of size 4 cannot test $5$-cycle-freeness in
constant time.
  In this paper we revisit the subgraph-freeness problem and show that
$5$-cycle-freeness, and indeed $H$-freeness for many other graphs $H$
comprising more than 4 vertices, can be tested in constant time. We show that
$C_k$-freeness can be tested in $O(1/\epsilon)$ rounds for any cycle $C_k$,
improving on the running time of $O(1/\epsilon^2)$ of the previous algorithms
for triangle-freeness and $C_4$-freeness. In the special case of triangles, we
show that triangle-freeness can be solved in $O(1)$ rounds independently of
$\epsilon$, when $\epsilon$ is not too small with respect to the number of
nodes and edges. We also show that $T$-freeness for any constant-size tree $T$
can be tested in $O(1)$ rounds, even without the property-testing relaxation.
Building on these results, we define a general class of graphs for which we can
test subgraph-freeness in $O(1/\epsilon)$ rounds. This class includes all
graphs over 5 vertices except the 5-clique, $K_5$. For cliques $K_s$ over $s
\geq 3$ nodes, we show that $K_s$-freeness can be tested in
$O(m^{1/2-1/(s-2)}/\epsilon^{1/2+1/(s-2)})$ rounds, where $m$ is the number of
edges.
