diff --git a/man/perf.assess.Rd b/man/perf.assess.Rd
index 914b96fa..84a7de9e 100644
--- a/man/perf.assess.Rd
+++ b/man/perf.assess.Rd
@@ -302,7 +302,8 @@ length(liver.toxicity$treatment$Treatment.Group) # 64 samples
 plsda.res <- plsda(liver.toxicity$gene, liver.toxicity$treatment$Treatment.Group, ncomp = 2)
 
 performance <- perf.assess(plsda.res, 
-                           validation = "Mfold", folds = 3, nrepeat = 10, # to make sure each fold has all classes represented
+                        # to make sure each fold has all classes represented
+                           validation = "Mfold", folds = 3, nrepeat = 10, 
                            seed = 12) # for reproducibility, remove for analysis
 
 performance$error.rate$BER
@@ -313,7 +314,7 @@ splsda.res <- splsda(liver.toxicity$gene, liver.toxicity$treatment$Treatment.Gro
                      keepX = c(25, 25), ncomp = 2)
 
 performance <- perf.assess(splsda.res,
-                           validation = "Mfold", folds = 3, nrepeat = 10, # to make sure each fold has all classes represented
+                           validation = "Mfold", folds = 3, nrepeat = 10, 
                            seed = 12)
 
 performance$error.rate$BER # can see slight improvement in error rate over PLS-DA example
@@ -325,20 +326,22 @@ ncol(liver.toxicity$clinic) # 10 Y variables as output of PLS model
 pls.res <- pls(liver.toxicity$gene, liver.toxicity$clinic, ncomp = 2)
 
 performance <- perf.assess(pls.res, 
-                           validation = "Mfold", folds = 3, nrepeat = 10, # to make sure each fold has all classes represented
+                           validation = "Mfold", folds = 3, nrepeat = 10,
                            seed = 12)
 
-performance$measures$Q2$summary # see Q2 which gives indication of predictive ability for each of the 10 Y outputs
+# see Q2 which gives indication of predictive ability for each of the 10 Y outputs
+performance$measures$Q2$summary 
 
 ## sPLS example
 
 spls.res <- spls(liver.toxicity$gene, liver.toxicity$clinic, ncomp = 2, keepX = c(50, 50))
 
 performance <- perf.assess(spls.res, 
-                           validation = "Mfold", folds = 3, nrepeat = 10, # to make sure each fold has all classes represented
+                           validation = "Mfold", folds = 3, nrepeat = 10, 
                            seed = 12)
 
-performance$measures$Q2$summary # see Q2 which gives indication of predictive ability for each of the 10 Y outputs
+# see Q2 which gives indication of predictive ability for each of the 10 Y outputs
+performance$measures$Q2$summary
 
 
 ## block PLS-DA example
diff --git a/tests/testthat/test-tune.block.plsda.R b/tests/testthat/test-tune.block.plsda.R
index 21ebdf7f..9ede1dd0 100644
--- a/tests/testthat/test-tune.block.plsda.R
+++ b/tests/testthat/test-tune.block.plsda.R
@@ -42,6 +42,8 @@ test_that("tune.block.plsda works and is the same as perf alone and in tune wrap
   .expect_numerically_close(tune.res.3$error.rate.per.class$mrna$max.dist[3,2], 0.25)
   
   # check can plot outputs
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune.res.1))
   expect_silent(plot(tune.res.2))
   expect_silent(plot(tune.res.3))
diff --git a/tests/testthat/test-tune.block.splsda.R b/tests/testthat/test-tune.block.splsda.R
index 6c24f436..a5caf1f5 100644
--- a/tests/testthat/test-tune.block.splsda.R
+++ b/tests/testthat/test-tune.block.splsda.R
@@ -159,6 +159,8 @@ test_that("tune.block.splsda works independently and in tune wrapper the same",
   expect_equal(tune11$choice.keepX, tune41$choice.keepX)
   
   # check can plot outputs
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune41))
   expect_silent(plot(tune11))
 
diff --git a/tests/testthat/test-tune.mint.plsda.R b/tests/testthat/test-tune.mint.plsda.R
index 34ee9b42..d65b575b 100644
--- a/tests/testthat/test-tune.mint.plsda.R
+++ b/tests/testthat/test-tune.mint.plsda.R
@@ -36,6 +36,8 @@ test_that("tune.mint.plsda works and is the same perf alone and in tune wrapper"
   .expect_numerically_close(tune.res.3$global.error$BER[1,1], 0.3803556)
   
   # check can plot outputs
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune.res.1))
   expect_silent(plot(tune.res.2))
   expect_silent(plot(tune.res.3))
diff --git a/tests/testthat/test-tune.mint.splsda.R b/tests/testthat/test-tune.mint.splsda.R
index 58630e7e..8719f6bf 100644
--- a/tests/testthat/test-tune.mint.splsda.R
+++ b/tests/testthat/test-tune.mint.splsda.R
@@ -21,7 +21,9 @@ test_that("tune.mint.splsda works", code = {
     expect_equal(out$choice.ncomp$ncomp, 1)
     
     # check can plot
-    expect_silent(plot(out))
+    pdf(NULL)
+    on.exit(dev.off())
+    expect_error(plot(out), NA) # makes note about not being able to plot SD bars
     
 })
 
@@ -47,7 +49,9 @@ test_that("tune.mint.splsda works with custom alpha", code = {
     expect_equal(out$choice.ncomp$ncomp, 1)
     
     # check can plot
-    expect_silent(plot(out))
+    pdf(NULL)
+    on.exit(dev.off())
+    expect_error(plot(out), NA) # makes note about not being able to plot SD bars
     
 })
 
diff --git a/tests/testthat/test-tune.pca.R b/tests/testthat/test-tune.pca.R
index 98b61e45..77e9afac 100644
--- a/tests/testthat/test-tune.pca.R
+++ b/tests/testthat/test-tune.pca.R
@@ -9,6 +9,8 @@ test_that("tune.pca and tune(method='pca') are equivalent", {
   expect_equal(object1$ncomp, object2$ncomp)
   expect_equal(object1$sdev[1], object2$sdev[1])
   # check can plot outputs without errors
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(object1))
   expect_silent(plot(object2))
 })
diff --git a/tests/testthat/test-tune.pls.R b/tests/testthat/test-tune.pls.R
index 0bdb1012..9b0fba35 100644
--- a/tests/testthat/test-tune.pls.R
+++ b/tests/testthat/test-tune.pls.R
@@ -31,6 +31,8 @@ test_that("tune.pls works and is the same as perf alone and in tune wrapper", co
   .expect_numerically_close(tune.res.3$measures$Q2$summary[1,3], -0.1304012)
   
   # check can plot outputs
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune.res.1))
   expect_silent(plot(tune.res.2))
   expect_silent(plot(tune.res.3))
diff --git a/tests/testthat/test-tune.plsda.R b/tests/testthat/test-tune.plsda.R
index d84c1e89..9ee1a112 100644
--- a/tests/testthat/test-tune.plsda.R
+++ b/tests/testthat/test-tune.plsda.R
@@ -43,6 +43,8 @@ test_that("tune.plsda works and is the same perf alone and in tune wrapper", cod
   .expect_numerically_close(tune.plsda.res.3$error.rate$overall[1,1], 0.5106383)
   
   # check can plot
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune.plsda.res.1))
   expect_silent(plot(tune.plsda.res.2))
   expect_silent(plot(tune.plsda.res.3))
diff --git a/tests/testthat/test-tune.rcc.R b/tests/testthat/test-tune.rcc.R
index 7c241f45..7cf83a5c 100644
--- a/tests/testthat/test-tune.rcc.R
+++ b/tests/testthat/test-tune.rcc.R
@@ -16,6 +16,8 @@ test_that("tune.rcc works with Mfold method", code = {
   expect_equal(tune.rcc.res$grid1, c(0.00100, 0.25075, 0.50050, 0.75025, 1.00000))
   
   # check can plot
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune.rcc.res))
 })
 
@@ -34,6 +36,8 @@ test_that("tune.rcc works with loo method", code = {
   expect_equal(tune.rcc.res$grid1, c(0.00100, 0.25075, 0.50050, 0.75025, 1.00000))
   
   # check can plot
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune.rcc.res))
 })
   
@@ -56,6 +60,8 @@ test_that("tune.rcc works in parallel same as in series", code = {
   expect_equal(tune.rcc.res$grid2, tune.rcc.res.parallel$grid2)
   
   # check can plot
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune.rcc.res))
   expect_silent(plot(tune.rcc.res.parallel))
 })
@@ -86,6 +92,8 @@ test_that("tune.rcc and tune(method='rcc') are equivalent", {
   expect_equal(tune.rcc.res.1$grid2, tune.rcc.res.2$grid2)
   
   # check can plot
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(tune.rcc.res.1))
   expect_silent(plot(tune.rcc.res.2))
   
diff --git a/tests/testthat/test-tune.spca.R b/tests/testthat/test-tune.spca.R
index 61e415db..d4fd6c75 100644
--- a/tests/testthat/test-tune.spca.R
+++ b/tests/testthat/test-tune.spca.R
@@ -20,6 +20,8 @@ test_that("tune.spca works in serial and parallel", {
   expect_equal(object_parallel$choice.keepX[[2]], 5)
   .expect_numerically_close(object_parallel$cor.comp$comp1[1,2], 0.3994544)
   # test can plot outputs
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(object_serial))
   expect_silent(plot(object_parallel))
 })
@@ -81,6 +83,8 @@ test_that("tune.spca and tune(method='spca') are equivalent", {
   expect_equal(object1$choice.keepX[[2]], object2$choice.keepX[[2]])
   .expect_numerically_close(object1$cor.comp$comp1[3,3], object2$cor.comp$comp1[3,3])
   # test can plot outputs
+  pdf(NULL)
+  on.exit(dev.off())
   expect_silent(plot(object1))
   expect_silent(plot(object2))
 })
diff --git a/tests/testthat/test-tune.splsda.R b/tests/testthat/test-tune.splsda.R
index 4abe2f18..3116f99f 100644
--- a/tests/testthat/test-tune.splsda.R
+++ b/tests/testthat/test-tune.splsda.R
@@ -31,11 +31,13 @@ test_that("tune.splsda works and is the same in parallel and when run in tune wr
                          method = "splsda")
   
   
-  # check outputs
+  # check outputs format
   expect_equal(class(tune.splsda.res.1), "tune.splsda")
   expect_equal(class(tune.splsda.res.2), "tune.splsda")
   expect_equal(class(tune.splsda.res.3), "tune.splsda")
   expect_equal(class(tune.splsda.res.4), "tune.splsda")
+  
+  # check output values
   expect_equal(unname(tune.splsda.res.1$choice.keepX), c(10,15))
   expect_equal(unname(tune.splsda.res.2$choice.keepX), c(10,15))
   expect_equal(unname(tune.splsda.res.3$choice.keepX), c(10,15))
@@ -46,10 +48,10 @@ test_that("tune.splsda works and is the same in parallel and when run in tune wr
   .expect_numerically_close(tune.splsda.res.4$error.rate[1,1], 0.3111111)
   
   # check can plot outputs
-  expect_silent(plot(tune.splsda.res.1))
-  expect_silent(plot(tune.splsda.res.2))
-  expect_silent(plot(tune.splsda.res.3))
-  expect_silent(plot(tune.splsda.res.4))
+  expect_is(plot(tune.splsda.res.1), "ggplot")
+  expect_is(plot(tune.splsda.res.2), "ggplot")
+  expect_is(plot(tune.splsda.res.3), "ggplot")
+  expect_is(plot(tune.splsda.res.4), "ggplot")
   
 })