address uninformative error for set_engine(NULL) (closes #1199)

Author: simonpcouch

R/engines.R

@@ -124,7 +124,7 @@ set_engine.model_spec <- function(object, engine, ...) {
     check_spec_mode_engine_val(mod_type, object$engine, object$mode)
   }
 
-  if (object$engine == "liquidSVM") {
+  if (!is.null(object$engine) && object$engine == "liquidSVM") {
     lifecycle::deprecate_warn(
       "0.1.6",
       "set_engine(engine = 'cannot be liquidSVM')",

tests/testthat/_snaps/nearest_neighbor.md

@@ -23,14 +23,6 @@
       Error in `nearest_neighbor()`:
       ! "reallyunknown" is not a known mode for model `nearest_neighbor()`.
 
----
-
-    Code
-      nearest_neighbor() %>% set_engine(NULL)
-    Condition
-      Error in `if (object$engine == "liquidSVM") ...`:
-      ! argument is of length zero
-
 # check_args() works
 
     Code

tests/testthat/_snaps/rand_forest.md

@@ -18,10 +18,9 @@
 # bad input
 
     Code
-      translate(rand_forest(mode = "classification") %>% set_engine(NULL))
-    Condition
-      Error in `if (object$engine == "liquidSVM") ...`:
-      ! argument is of length zero
+      res <- translate(rand_forest(mode = "classification") %>% set_engine(NULL))
+    Message
+      Used `engine = 'ranger'` for translation.
 
 ---
 

tests/testthat/_snaps/surv_reg.md

@@ -31,10 +31,9 @@
 ---
 
     Code
-      translate(surv_reg() %>% set_engine(NULL))
-    Condition
-      Error in `if (object$engine == "liquidSVM") ...`:
-      ! argument is of length zero
+      res <- translate(surv_reg() %>% set_engine(NULL))
+    Message
+      Used `engine = 'survival'` for translation.
 
 # deprecation warning
 

tests/testthat/_snaps/svm_linear.md

@@ -20,8 +20,8 @@
     Code
       translate(svm_linear(mode = "regression") %>% set_engine(NULL))
     Condition
-      Error in `if (object$engine == "liquidSVM") ...`:
-      ! argument is of length zero
+      Error in `translate.default()`:
+      ! Please set an engine.
 
 ---
 

tests/testthat/_snaps/svm_poly.md

@@ -26,8 +26,8 @@
 ---
 
     Code
-      svm_poly() %>% set_engine(NULL)
+      svm_poly() %>% set_engine(NULL) %>% translate()
     Condition
-      Error in `if (object$engine == "liquidSVM") ...`:
-      ! argument is of length zero
+      Error in `translate.default()`:
+      ! Please set an engine.
 

tests/testthat/_snaps/svm_rbf.md

@@ -48,6 +48,6 @@
     Code
       translate(svm_rbf(mode = "regression") %>% set_engine(NULL))
     Condition
-      Error in `if (object$engine == "liquidSVM") ...`:
-      ! argument is of length zero
+      Error in `translate.default()`:
+      ! Please set an engine.
 

tests/testthat/test-nearest_neighbor.R

@@ -8,18 +8,17 @@ test_that('updating', {
 
 test_that('bad input', {
   expect_snapshot(error = TRUE, nearest_neighbor(mode = "reallyunknown"))
-  expect_snapshot(error = TRUE, nearest_neighbor() %>% set_engine( NULL))
 })
 
 test_that('check_args() works', {
   skip_if_not_installed("kknn")
 
   hpc <- hpc_data[1:150, c(2:5, 8)]
-  
+
   expect_snapshot(
     error = TRUE,
     {
-      spec <- nearest_neighbor(neighbors = -1) %>% 
+      spec <- nearest_neighbor(neighbors = -1) %>%
         set_engine("kknn") %>%
         set_mode("classification")
       fit(spec, class ~ ., hpc)
@@ -28,7 +27,7 @@ test_that('check_args() works', {
   expect_snapshot(
     error = TRUE,
     {
-      spec <- nearest_neighbor(weight_func = 2) %>% 
+      spec <- nearest_neighbor(weight_func = 2) %>%
         set_engine("kknn") %>%
         set_mode("classification")
       fit(spec, class ~ ., hpc)

tests/testthat/test-rand_forest.R

@@ -8,7 +8,7 @@ test_that('updating', {
 })
 
 test_that('bad input', {
-  expect_snapshot(error = TRUE, translate(rand_forest(mode = "classification") %>% set_engine(NULL)))
+  expect_snapshot(res <- translate(rand_forest(mode = "classification") %>% set_engine(NULL)))
   expect_snapshot(error = TRUE, rand_forest(mode = "time series"))
   expect_snapshot(error = TRUE, translate(rand_forest(mode = "classification") %>% set_engine("wat?")))
   expect_snapshot(error = TRUE, translate(rand_forest(mode = "classification", ytest = 2)))
@@ -17,4 +17,4 @@ test_that('bad input', {
 test_that("check_args() works", {
   # Here for completeness, no checking is done
   expect_true(TRUE)
-}) 
+})

tests/testthat/test-surv_reg.R

@@ -13,7 +13,7 @@ test_that('bad input', {
 
   expect_snapshot(error = TRUE, surv_reg(mode = ", classification"))
   expect_snapshot(error = TRUE, translate(surv_reg() %>% set_engine("wat")))
-  expect_snapshot(error = TRUE, translate(surv_reg() %>% set_engine(NULL)))
+  expect_snapshot(res <- translate(surv_reg() %>% set_engine(NULL)))
 })
 
 test_that("deprecation warning", {