From a45d4f7d686aa6b57ce25f342a71eea79507f01c Mon Sep 17 00:00:00 2001
From: Andrew Johnson <andrew.johnson@arjohnsonau.com>
Date: Sat, 15 Jun 2024 18:22:33 +0300
Subject: [PATCH] Fix factor arg handling (#999)

---
 R/data.R                   | 21 +++++++++++----------
 tests/testthat/test-data.R |  3 +++
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/R/data.R b/R/data.R
index ce5b9cf6..f483ba4c 100644
--- a/R/data.R
+++ b/R/data.R
@@ -186,18 +186,19 @@ process_data <- function(data, model_variables = NULL) {
         # generating a decimal point in write_stan_json
         if (data_variables[[var_name]]$type == "int"
             && !is.integer(data[[var_name]])) {
-          if (!isTRUE(all(is_wholenumber(data[[var_name]])))) {
-            # Don't warn for NULL/NA, as different warnings are used for those
-            if (!isTRUE(any(is.na(data[[var_name]])))) {
-              warning("A non-integer value was supplied for '", var_name, "'!",
-                      " It will be truncated to an integer.", call. = FALSE)
+          if (!is.factor(data[[var_name]])) {
+            if (!isTRUE(all(is_wholenumber(data[[var_name]])))) {
+              # Don't warn for NULL/NA, as different warnings are used for those
+              if (!isTRUE(any(is.na(data[[var_name]])))) {
+                warning("A non-integer value was supplied for '", var_name, "'!",
+                        " It will be truncated to an integer.", call. = FALSE)
+              }
+            } else {
+              # Round before setting mode to integer to avoid floating point errors
+              data[[var_name]] <- round(data[[var_name]])
             }
-            mode(data[[var_name]]) <- "integer"
-          } else {
-            # Round before setting mode to integer to avoid floating point errors
-            data[[var_name]] <- round(data[[var_name]])
-            mode(data[[var_name]]) <- "integer"
           }
+          mode(data[[var_name]]) <- "integer"
         }
       }
     }
diff --git a/tests/testthat/test-data.R b/tests/testthat/test-data.R
index 61ca79e3..c7283d9b 100644
--- a/tests/testthat/test-data.R
+++ b/tests/testthat/test-data.R
@@ -383,6 +383,9 @@ test_that("process_data warns on int coercion", {
   expect_no_warning(
     process_data(list(a = c(1, 2, 3)), model_variables = mod$variables())
   )
+  expect_no_warning(
+    process_data(list(a = factor(c("a", "b", "c"))), model_variables = mod$variables())
+  )
 })
 
 test_that("Floating-point differences do not cause truncation towards 0", {