[BP] Fix early stopping with linear model. (#7554) (#7562)

R-package/tests/testthat/test_glm.R

@@ -46,3 +46,31 @@ test_that("gblinear works", {
   expect_equal(dim(h), c(n, ncol(dtrain) + 1))
   expect_s4_class(h, "dgCMatrix")
 })
+
+test_that("gblinear early stopping works", {
+  data(agaricus.train, package = 'xgboost')
+  data(agaricus.test, package = 'xgboost')
+  dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label)
+  dtest <- xgb.DMatrix(agaricus.test$data, label = agaricus.test$label)
+
+  param <- list(
+    objective = "binary:logistic", eval_metric = "error", booster = "gblinear",
+    nthread = 2, eta = 0.8, alpha = 0.0001, lambda = 0.0001,
+    updater = "coord_descent"
+  )
+
+  es_round <- 1
+  n <- 10
+  booster <- xgb.train(
+    param, dtrain, n, list(eval = dtest, train = dtrain), early_stopping_rounds = es_round
+  )
+  expect_equal(booster$best_iteration, 5)
+  predt_es <- predict(booster, dtrain)
+
+  n <- booster$best_iteration + es_round
+  booster <- xgb.train(
+    param, dtrain, n, list(eval = dtest, train = dtrain), early_stopping_rounds = es_round
+  )
+  predt <- predict(booster, dtrain)
+  expect_equal(predt_es, predt)
+})