--- a
+++ b/tests/testthat/test-get_grn.R
@@ -0,0 +1,38 @@
+context("get_grn")
+
+#' data(HeLa)
+#' #' # grn only on gene
+#' cluster.mRNA <- HeLa$getCluster %>% dplyr::filter(block == "mRNA")
+#' X <- HeLa$raw$mRNA
+#' #grn.res <- get_grn(X = HeLa$raw$mRNA, cluster = cluster.mRNA, method = "aracne")
+#' 
+data("hmp_T2D")
+cluster.mRNA <- hmp_T2D$getCluster.res %>% dplyr::filter(block == "RNA")
+X <- hmp_T2D$raw$RNA
+
+test_that("get_grn fails on invalid input - X", {
+    # X
+    expect_error(get_grn(X = ""), "'X' must be a numeric matrix/data.frame", fixed = TRUE)
+    expect_error(get_grn(X = 1), "'X' must be a numeric matrix/data.frame", fixed = TRUE)
+    expect_error(get_grn(X = NA), "'X' must be a numeric matrix/data.frame", fixed = TRUE)
+    expect_error(get_grn(X = list()), "'X' must be a numeric matrix/data.frame", fixed = TRUE)
+    
+})
+
+
+test_that("get_grn fails on invalid input - X", {
+    expect_error(get_grn(X = X, cluster = ""), "cluster must be NULL or a result from getCluster()", fixed = TRUE)
+})
+
+test_that("get_grn fails on invalid input - method", {
+    expect_error(get_grn(X = X, cluster = NULL, method = ""))
+})
+
+test_that("get_grn works", {
+    # expect_is(get_grn(X = X, cluster = cluster.mRNA, method = "aracne"), "list.igraph")
+    expect_warning(get_grn(X = X, cluster = cluster.mRNA, method = "aracne"))
+    
+    # expect_is(get_grn(X = X, method = "aracne"), "igraph")
+    expect_warning(get_grn(X = X, method = "aracne"))
+    
+})