diff --git a/man/assert.Rd b/man/assert.Rd
new file mode 100644
index 0000000..bb5f212
--- /dev/null
+++ b/man/assert.Rd
@@ -0,0 +1,20 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/helper.r
+\name{assert}
+\alias{assert}
+\title{Simple function to assert given conditions}
+\usage{
+assert(statement, err_message = NULL)
+}
+\arguments{
+\item{statement}{vector of comparison to proof}
+
+\item{err_message}{string of error message when not all comparison are TRUE}
+}
+\value{
+character string used as error message or nothing if all TRUE
+}
+\description{
+Simple function to assert given conditions
+}
+\keyword{internal}
diff --git a/man/detect_reference.Rd b/man/detect_reference.Rd
index fb5de45..4a0b7d8 100644
--- a/man/detect_reference.Rd
+++ b/man/detect_reference.Rd
@@ -1,5 +1,5 @@
 % Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/helper.r
+% Please edit documentation in R/backend.r
 \name{detect_reference}
 \alias{detect_reference}
 \title{Detect variable of input data used as 'reference'}
diff --git a/man/in_range.Rd b/man/in_range.Rd
new file mode 100644
index 0000000..fc78115
--- /dev/null
+++ b/man/in_range.Rd
@@ -0,0 +1,22 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/helper.r
+\name{in_range}
+\alias{in_range}
+\title{Check if value(s) is in specific range}
+\usage{
+in_range(x, min_, max_)
+}
+\arguments{
+\item{x}{single value or vector to test}
+
+\item{min_}{minimal allowed value}
+
+\item{max_}{maximal allowed value}
+}
+\value{
+boolean value of all values are in range
+}
+\description{
+Check if value(s) is in specific range
+}
+\keyword{internal}
diff --git a/man/prepare.Rd b/man/prepare.Rd
index 16cbfee..5c11fae 100644
--- a/man/prepare.Rd
+++ b/man/prepare.Rd
@@ -1,5 +1,5 @@
 % Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/helper.r
+% Please edit documentation in R/backend.r
 \name{prepare}
 \alias{prepare}
 \title{Prepare input data}
diff --git a/tests/testthat/test_backend.R b/tests/testthat/test_backend.R
index 60678b4..7b00b2c 100644
--- a/tests/testthat/test_backend.R
+++ b/tests/testthat/test_backend.R
@@ -29,3 +29,14 @@ test_that("prepare() works", {
     df$efficiency <- 40
     expect_equal(unique(prepare(df)$E), 1.4)
 })
+
+test_that("conflate works()", {
+    run <- get_reference_group(qpcR(dat, hkg = "HKG", reference = "control", groups = "dpi", aggregate = FALSE))
+    control_groups <- aggregate(rexpr ~ gene + dpi, data = run, FUN = mean)
+    expect_equal(unique(control_groups$rexpr), c(1, 1))
+
+    run2 <- get_reference_group(qpcR(dat, hkg = c("HKG", "HKG2"), reference = "control", groups = "dpi", aggregate = FALSE))
+    control_groups2 <- aggregate(rexpr ~ gene + dpi, data = run2, FUN = mean)
+    expect_equal(unique(control_groups2$rexpr), c(1, 1))
+
+})
\ No newline at end of file
diff --git a/tests/testthat/test_qpcr.R b/tests/testthat/test_qpcr.R
index 3b1f894..a1c256c 100644
--- a/tests/testthat/test_qpcr.R
+++ b/tests/testthat/test_qpcr.R
@@ -1,14 +1,6 @@
 dat <- read.table("example2.tsv", sep = "\t", head = TRUE)
 
 test_that("qpcR() works", {
-    run <- get_reference_group(qpcR(dat, hkg = "HKG", reference = "control", groups = "dpi", aggregate = FALSE))
-    control_groups <- aggregate(rexpr ~ gene + dpi, data = run, FUN = mean)
-    expect_equal(unique(control_groups$rexpr), c(1, 1))
-
-    run2 <- get_reference_group(qpcR(dat, hkg = c("HKG", "HKG2"), reference = "control", groups = "dpi", aggregate = FALSE))
-    control_groups2 <- aggregate(rexpr ~ gene + dpi, data = run2, FUN = mean)
-    expect_equal(unique(control_groups2$rexpr), c(1, 1))
-
     expect_no_error(qpcR(dat, hkg = "HKG", groups = "dpi", outlier.method = "interquartile"))
     expect_no_error(qpcR(dat, hkg = "HKG", groups = "dpi", outlier.method = "z-score"))
     expect_no_error(qpcR(dat, hkg = "HKG", groups = "dpi", outlier.method = "hampel"))
@@ -18,6 +10,11 @@ test_that("qpcR() works", {
     expect_no_error(qpcR(dat, hkg = c("HKG", "HKG2"), groups = "dpi", outlier.method = "hampel"))
 })
 
+test_that("expression values of reference group equals 1", {
+    res <- qpcR(dat, hkg = "HKG", reference = "control", groups = "dpi", aggregate = TRUE)
+    expect_equal(unique(res[res == "control", ]$rexpr.mean, ), c(1, 1))
+})
+
 test_that("output equals data.frame", {
     expect_type(qpcR(dat, hkg = "HKG", groups = "dpi"), "list")
     expect_type(qpcR(dat, hkg = c("HKG", "HKG2"), groups = "dpi"), "list")