add reproducibility test

tests/testthat/test_reproducibility.R

@@ -0,0 +1,20 @@
+## Tests for cross-platform reproducibility
+
+library(ranger)
+context("ranger_repro")
+
+test_that("returns same predictions as before, R seed", {
+  set.seed(2023)
+  rf <- ranger(Species ~ ., iris, probability = TRUE)
+  pred <- predict(rf, iris)
+
+  expect_equal(pred$predictions[148:150, 3], c(1.0, 0.9940865, 0.9197802), tolerance = 1e-5)
+})
+
+test_that("returns same predictions as before, cpp seed", {
+  set.seed(2023)
+  rf <- ranger(Species ~ ., iris, probability = TRUE, seed = 2023)
+  pred <- predict(rf, iris, seed = 2023)
+
+  expect_equal(pred$predictions[148:150, 3], c(1.0000000, 0.9919810, 0.9377452), tolerance = 1e-5)
+})