--- a
+++ b/tests/testthat/test-tuneCluster.spca.R
@@ -0,0 +1,41 @@
+context("tuneCluster.spca")
+
+demo <- suppressWarnings(get_demo_cluster())
+X <- demo$X
+tune.spca.res <- tuneCluster.spca(X = X, ncomp = 2, test.keepX = c(2:9))
+# plot(tune.spca.res)
+
+pdf(NULL)
+test_that("tuneCluster.spca failed on invalid input - X", {
+    expect_error(tuneCluster.spca(X = ""), "X must be a numeric matrix/data.frame", fixed = TRUE)
+    expect_error(tuneCluster.spca(X = 1), "X must be a numeric matrix/data.frame", fixed = TRUE)
+    expect_error(tuneCluster.spca(X = NA), "X must be a numeric matrix/data.frame", fixed = TRUE)
+    expect_error(tuneCluster.spca(X = list()), "X must be a numeric matrix/data.frame", fixed = TRUE)
+})
+
+test_that("tuneCluster.spca failed on invalid input - ncomp", {
+    expect_error(tuneCluster.spca(X = demo$X, ncomp = ""), "'ncomp' should be an integer between 1 and 10", fixed = TRUE)
+    expect_error(tuneCluster.spca(X = demo$X, ncomp = c(1,2)), "'ncomp' should be an integer between 1 and 10", fixed = TRUE)
+    expect_error(tuneCluster.spca(X = demo$X, ncomp = 0), "'ncomp' should be an integer between 1 and 10", fixed = TRUE)
+    # ncomp < nrow(X)
+    expect_error(tuneCluster.spca(X = demo$X, ncomp = 11),"'ncomp' should be an integer between 1 and 10", fixed = TRUE)
+})
+
+test_that("tuneCluster.spca failed on invalid input - keepX", {
+    expect_error(tuneCluster.spca(X = demo$X, ncomp = 2, test.keepX = c("a",1)), "'test.keepX' should be numeric", fixed = TRUE)
+    expect_error(tuneCluster.spca(X = demo$X, ncomp = 2, test.keepX = list()), "'test.keepX' should be numeric", fixed = TRUE)
+    expect_error(tuneCluster.spca(X = demo$X, ncomp = 2, test.keepX = "abc"), "'test.keepX' should be numeric", fixed = TRUE)
+    expect_error(tuneCluster.spca(X = demo$X, ncomp = 2, test.keepX = matrix(1:9)), "'test.keepX' should be numeric", fixed = TRUE)
+})
+
+test_that("tuneCluster.spca works", {
+    expect_is(tuneCluster.spca(X = X, ncomp = 2, test.keepX = c(5:10)), "spca.tune.silhouette")
+    expect_is(tuneCluster.spca(X = X, ncomp = 2, test.keepX = NULL), "spca.tune.silhouette")
+    expect_is(tuneCluster.spca(X = as.data.frame(X), ncomp = 3, test.keepX = c(5:10)), "spca.tune.silhouette")
+})
+
+test_that("plot.spca.tune.silhouette works", {
+    #-- comp
+    expect_is(plot(tune.spca.res), "ggplot")
+})
+dev.off()
\ No newline at end of file