Improved tests [skip ci]

Author: ankane

test/dataset_test.rb

@@ -70,6 +70,9 @@ def test_matrix
     data = Matrix.build(3, 3) { |row, col| row + col }
     label = Vector.elements([4, 5, 6])
     dataset = LightGBM::Dataset.new(data, label: label)
+    assert_equal 3, dataset.num_data
+    assert_equal 3, dataset.num_feature
+    assert_equal 3, dataset.label.size
     assert_equal ["Column_0", "Column_1", "Column_2"], dataset.feature_name
   end
 
@@ -78,6 +81,9 @@ def test_daru
     label = data["y"]
     data = data.delete_vector("y")
     dataset = LightGBM::Dataset.new(data, label: label)
+    assert_equal 500, dataset.num_data
+    assert_equal 4, dataset.num_feature
+    assert_equal 500, dataset.label.size
     assert_equal ["x0", "x1", "x2", "x3"], dataset.feature_name
   end
 
@@ -88,6 +94,9 @@ def test_numo
     data = Numo::DFloat.new(3, 5).seq
     label = Numo::DFloat.new(3).seq
     dataset = LightGBM::Dataset.new(data, label: label)
+    assert_equal 3, dataset.num_data
+    assert_equal 5, dataset.num_feature
+    assert_equal 3, dataset.label.size
     assert_equal ["Column_0", "Column_1", "Column_2", "Column_3", "Column_4"], dataset.feature_name
   end
 
@@ -98,6 +107,9 @@ def test_rover
     data = Rover.read_csv(data_path)
     label = data.delete("y")
     dataset = LightGBM::Dataset.new(data, label: label)
+    assert_equal 500, dataset.num_data
+    assert_equal 4, dataset.num_feature
+    assert_equal 500, dataset.label.size
     assert_equal ["x0", "x1", "x2", "x3"], dataset.feature_name
   end