tergm_MCMC_sample() now provides informative error messages on variou…

…s MCMC failures; tests have been added. (Thanks to Rodrigo Anderle and Sandra Flores Alvarado for flagging the matter.)

fixes #122

R/tergm.getMCMCsample.R

@@ -68,6 +68,14 @@ tergm_MCMC_sample <- function(nw, model, model.mon = NULL,
 
   z <- tergm_MCMC_slave(state, eta.comb, control, verbose)
 
+  if(z$status)
+    stop(switch(z$status,
+                paste0("Number of edges in a simulated network exceeds the maximum set by the ", sQuote("MCMC.maxedges"), " control parameter."), # 1: MCMCDyn_TOO_MANY_EDGES
+                "A Metropolis-Hastings proposal has failed.", # 2: MCMCDyn_MH_FAILED
+                paste0("Logging of changes in the network has been requested, and the storage capacity specified by ", sQuote("MCMC.maxchanges"), " has been exceeded.") # 3: MCMCDyn_TOO_MANY_CHANGES
+                )
+         )
+
   state <- z$state
 
   diffedgelist<-if(control$changes) {
@@ -137,7 +145,7 @@ tergm_MCMC_slave <- function(state, eta, control, verbose){
              as.integer(verbose),
              PACKAGE="tergm")
 
-  if(z$status != 0) stop("MCMCDyn failed with error code ", z$status)
+  if(z$status) return(z) # If there is an error.
 
   z$state <- update(z$state)
 

tests/testthat/helper-CMLE.R

@@ -10,7 +10,7 @@
 logit<-function(p) log(p/(1-p))
 ilogit<-function(x) 1/(1+exp(-x))
 
-o <- options(tergm.eval.loglik=FALSE)
+options(tergm.eval.loglik = FALSE, useFancyQuotes = FALSE)
 
 CMLE.tools <- new.env()
 

tests/testthat/test-simulate.R

@@ -285,6 +285,16 @@ test_that("simulate.networkDynamic behaves reasonably", {
   expect_equal(unname(summary(network.collapse(new_nwD_constr2, at = 20) ~ concurrent)), 0)
 })
 
+test_that("Dynamic simulation error messages are correct", {
+  nw <- network.initialize(100, directed = FALSE)
+
+  expect_error(simulate(nw ~ Form(~edges) + Persist(~edges), coef = c(5, 5), dynamic = TRUE, control = control.simulate.formula.tergm(MCMC.maxedges=2)),
+               "^Number of edges in a simulated network exceeds the maximum set by the 'MCMC.maxedges' control parameter.$")
+
+  expect_error(simulate(nw ~ Form(~edges) + Persist(~edges), coef = c(5, 5), dynamic = TRUE, control = control.simulate.formula.tergm(MCMC.maxchanges=2)),
+               "^Logging of changes in the network has been requested, and the storage capacity specified by 'MCMC.maxchanges' has been exceeded.$")
+})
+
 statnet.common::opttest({
 test_that("simulate.tergm behaves reasonably", {
   nw <- network.initialize(100, directed = FALSE)