add midline/cline support to collapse_rows
diff --git a/tests/visual_tests/collapse_rows_pdf.Rmd b/tests/visual_tests/collapse_rows_pdf.Rmd
index a2f1138..deb4f39 100644
--- a/tests/visual_tests/collapse_rows_pdf.Rmd
+++ b/tests/visual_tests/collapse_rows_pdf.Rmd
@@ -1,17 +1,18 @@
 ---
 title: "Untitled"
-output: pdf_document
+output: 
+  pdf_document:
+    keep_tex: true
 ---
 
 ```{r}
 library(knitr)
 library(kableExtra)
 collapse_rows_dt <- data.frame(C1 = c(rep("aaaaaa aaaaaa", 10), rep("bbbbb bbbbbb", 5)),
-                 C2 = c(rep("c", 7), rep("d", 3), rep("c", 2), rep("d", 3)),
+                 C2 = c(rep("c", 7), rep("d", 4), rep("c", 2), rep("d", 2)),
                  C3 = 1:15,
                  C4 = sample(c(0,1), 15, replace = TRUE))
 kable(collapse_rows_dt, "latex", align = "c", booktabs = T) %>%
-  kable_styling() %>%
-  column_spec(1, bold=T, width = "2em") %>%
-  collapse_rows(1)
+  column_spec(1, bold = T, width = "5em") %>%
+  collapse_rows(1:2)
 ```