def METHOD_NAME(self):
    """Test qqplot()"""
    np.random.seed(123)
    x = np.random.normal(size=50)
    x_ln = np.random.lognormal(size=50)
    x_exp = np.random.exponential(size=50)
    ax = qqplot(x, dist="norm")
    assert isinstance(ax, matplotlib.axes.Axes)
    _, (ax1, ax2) = plt.subplots(1, 2, figsize=(9, 4))
    qqplot(x_exp, dist="expon", ax=ax2, color="black", marker="+")
    mean, std = 0, 0.8
    qqplot(x, dist=stats.norm, sparams=(mean, std), confidence=False)
    # For lognormal distribution, the shape parameter must be specified
    ax = qqplot(x_ln, dist="lognorm", sparams=(1))
    assert isinstance(ax, matplotlib.axes.Axes)
    # Error: required parameters are not specified
    with pytest.raises(ValueError):
        qqplot(x_ln, dist="lognorm", sparams=())
    plt.close("all")