--- a
+++ b/tests/testthat/test_sim_ctd.R
@@ -0,0 +1,28 @@
+context("Test sim_ctd")
+
+## test output format ##
+test_that("sim_ctd working as expected", {
+    ## skip on CRAN
+    skip_on_cran()
+
+    ## get data
+    data(fake_outbreak)
+    x <- fake_outbreak
+    N <- length(x$ances)
+    tTree <- data.frame(i = x$ances, j = 1:N)
+
+    ## error check
+    expect_error(sim_ctd(tTree = tTree, eps = 1.1, lambda = 0),
+                 "eps and lambda must be probabilities")
+    
+    ## for eps = 1 / lambda = 0, there should be one
+    ## contact per transmission pair
+    ctd <- sim_ctd(tTree = tTree, eps = 1, lambda = 0)
+    expect_equal(nrow(ctd), sum(!is.na(x$ances)))
+
+    ## for eps = 1 / lambda = 1, ensure all possible
+    ## contacts are reported
+    ctd <- sim_ctd(tTree = tTree, eps = 1, lambda = 1)
+    expect_equal(nrow(ctd), N*(N-1)/2)
+
+})