isMinimumSpanningForest = (
    suspect,
    graph,
    minimumCost,
    connectivity
  ) => {
    assert(!graph.directed);
    return (
      isForest(suspect, connectivity || 1) &&
      spans(suspect, graph) &&
      graphCost(suspect) === minimumCost
    );
  }
Test whether one graph is the minimum spanning forest of the other.

@param {Graph} suspect
@param {Graph} graph - Undirected graph.
@param {?number} minimumCost
@param {number} [connectivity=1]
@return {boolean}