diff --git a/tests/testthat.R b/tests/testthat.R
index eae16bf..164aec2 100644
--- a/tests/testthat.R
+++ b/tests/testthat.R
@@ -1,7 +1,4 @@
 library(testthat)
 library(RClickhouse)
 
-serveraddr <- "127.0.0.1"
-tblname    <- "test"
-
 test_check("RClickhouse")
diff --git a/tests/testthat/test-array.R b/tests/testthat/test-array.R
index 5752f42..3a93404 100644
--- a/tests/testthat/test-array.R
+++ b/tests/testthat/test-array.R
@@ -1,36 +1,19 @@
 context("array")
 
 library(DBI, warn.conflicts=F)
-library(dplyr, warn.conflicts=F)
-library(dbplyr, warn.conflicts=F)
+library(dplyr, warn.conflicts=F)  # for data_frame
+
+source("utils.R")
 
 test_that("reading & writing array columns", {
-  skip_on_cran()
-  conn <- dbConnect(RClickhouse::clickhouse(), host=serveraddr)
-  df <- as.data.frame(data_frame(x=list(c(1,3,5),c(1,2))))
-  dbWriteTable(conn, tblname, df, overwrite=T)
-  r <- dbReadTable(conn, tblname)
-  expect_equal(r, df)
-  dbDisconnect(conn)
+  writeReadTest(as.data.frame(data_frame(x=list(c(1,3,5),c(1,2)))))
 })
 
 #TODO: fix bug in clickhouse-cpp first
 #test_that("nullable array columns", {
-#  conn <- dbConnect(RClickhouse::clickhouse(), host="localhost")
-#  df <- data.frame(x=I(list(c(1,3,5),c(1,2))))
-#  attributes(df$x) <- NULL
-#  dbWriteTable(conn, tblname, df, overwrite=T)
-#  r <- dbReadTable(conn, tblname)
-#  expect_equal(r, df)
-#  dbDisconnect(conn)
+#  writeReadTest(as.data.frame(data_frame(x=list(c(1,NA,3,5),c(1,2,NA)))))
 #})
 
 test_that("array columns with empty entries", {
-  skip_on_cran()
-  conn <- dbConnect(RClickhouse::clickhouse(), host=serveraddr)
-  df <- as.data.frame(data_frame(x=list(c(1,2,3),as.numeric(c()),c(4,5))))
-  dbWriteTable(conn, tblname, df, overwrite=T)
-  r <- dbReadTable(conn, tblname)
-  expect_equal(r, df)
-  dbDisconnect(conn)
+  writeReadTest(as.data.frame(data_frame(x=list(c(1,2,3),as.numeric(c()),c(4,5)))))
 })
diff --git a/tests/testthat/test-regr-15.R b/tests/testthat/test-regr-15.R
index 3e663e6..5059a5f 100644
--- a/tests/testthat/test-regr-15.R
+++ b/tests/testthat/test-regr-15.R
@@ -4,6 +4,8 @@ library(DBI, warn.conflicts=F)
 library(dplyr, warn.conflicts=F)
 library(dbplyr, warn.conflicts=F)
 
+source("utils.R")
+
 test_that("correct conversion of logical values in dplyr (#15)", {
   skip_on_cran()
   conn <- dbConnect(RClickhouse::clickhouse(), host=serveraddr)
diff --git a/tests/testthat/utils.R b/tests/testthat/utils.R
new file mode 100644
index 0000000..ce55d5c
--- /dev/null
+++ b/tests/testthat/utils.R
@@ -0,0 +1,11 @@
+serveraddr <- "127.0.0.1"
+tblname    <- "test"
+
+writeReadTest <- function(input, result = input) {
+  skip_on_cran()
+  conn <- dbConnect(RClickhouse::clickhouse(), host=serveraddr)
+  dbWriteTable(conn, tblname, input, overwrite=T)
+  r <- dbReadTable(conn, tblname)
+  expect_equal(r, result)
+  dbDisconnect(conn)
+}