Improve xgboost test. (#949)

- Add assertion.
- Stopped using deprecated label encoder (removes the following warning: https://paste.googleplex.com/6273615185051648)

Author: rosbo

tests/test_xgboost.py

@@ -1,9 +1,9 @@
 import unittest
 
+import numpy as np
 import xgboost
 
 from distutils.version import StrictVersion
-from sklearn import datasets
 from xgboost import XGBClassifier
 
 class TestXGBoost(unittest.TestCase):
@@ -12,8 +12,15 @@ def test_version(self):
         self.assertGreaterEqual(StrictVersion(xgboost.__version__), StrictVersion("1.2.1"))
 
     def test_classifier(self):
-        boston = datasets.load_boston()
-        X, y = boston.data, boston.target
+        X_train = np.random.random((100, 28))
+        y_train = np.random.randint(10, size=(100, 1))
+        X_test = np.random.random((100, 28))
+        y_test = np.random.randint(10, size=(100, 1))
 
-        xgb1 = XGBClassifier(n_estimators=3)
-        xgb1.fit(X[0:70],y[0:70])
+        xgb1 = XGBClassifier(n_estimators=3, use_label_encoder=False)
+        xgb1.fit(
+            X_train, y_train,
+            eval_set=[(X_train, y_train), (X_test, y_test)],
+            eval_metric='mlogloss',
+        )
+        self.assertIn("validation_0", xgb1.evals_result())