Add tests for listing export bug (#227)

See insightsengineering/formatters#323

Author: edelarua

tests/testthat/_snaps/export.md

@@ -258,3 +258,45 @@
       
       foot
 
+# export_as_txt works with empty listings
+
+    Code
+      cat(res)
+    Output
+                                                                                           
+      —————————————————————————————————————————————————————————————————————————————————————
+      Null Report: No observations met the reporting criteria for inclusion in this output.
+
+# export_as_txt works with listings with all key cols
+
+    Code
+      cat(res)
+    Output
+      Categorical Level Biomarker 2   Medication Class   Standardized Medication Name
+      ———————————————————————————————————————————————————————————————————————————————
+                   LOW                    medcl A               medname A_1/3        
+                                                                medname A_2/3        
+                                                                medname A_3/3        
+                                          medcl B               medname B_1/4        
+                                                                medname B_2/4        
+                                                                medname B_3/4        
+                                                                medname B_4/4        
+                                          medcl C               medname C_1/2        
+                                                                medname C_2/2        
+                 MEDIUM                   medcl A               medname A_2/3        
+                                                                medname A_3/3        
+                                          medcl B               medname B_1/4        
+                                                                medname B_2/4        
+                                                                medname B_3/4        
+                                                                medname B_4/4        
+                                          medcl C               medname C_1/2        
+                                                                medname C_2/2        
+                  HIGH                    medcl A               medname A_1/3        
+                                                                medname A_2/3        
+                                                                medname A_3/3        
+                                          medcl B               medname B_1/4        
+                                                                medname B_2/4        
+                                                                medname B_3/4        
+                                                                medname B_4/4        
+                                          medcl C               medname C_2/2        
+

tests/testthat/test-export.R

@@ -91,3 +91,25 @@ testthat::test_that("export_as_txt works with split_into_pages_by_var", {
   pages_listings <- export_as_txt(lsting, file = NULL, paginate = TRUE, lpp = 30, cpp = 65)
   testthat::expect_snapshot(cat(pages_listings))
 })
+
+testthat::test_that("export_as_txt works with empty listings", {
+  df <- data.frame(
+    x = with_label("Null Report: No observations met the reporting criteria for inclusion in this output.", "")
+  )
+  lsting <- as_listing(df)
+
+  res <- export_as_txt(lsting)
+  testthat::expect_snapshot(cat(res))
+})
+
+testthat::test_that("export_as_txt works with listings with all key cols", {
+  lsting <- as_listing(
+    df = ex_adcm[1:50, ],
+    key_cols = c("BMRKR2", "CMCLAS", "CMDECOD"),
+    disp_cols = c("BMRKR2", "CMCLAS", "CMDECOD"),
+    unique_rows = TRUE
+  )
+
+  res <- export_as_txt(lsting)
+  testthat::expect_snapshot(cat(res))
+})