def test_dt_output_shape(dummy_titanic):
    X_train, y_train, X_test, y_test = dummy_titanic
    dt = DecisionTree()
    dt.fit(X_train, y_train)
    pred_train = dt.predict(X_train)
    pred_test = dt.predict(X_test)

    assert pred_train.shape == (X_train.shape[0],), 'DecisionTree output should be same as training labels.'
    assert pred_test.shape == (X_test.shape[0],), 'DecisionTree output should be same as testing labels.'