I can not test the Swing GUI with AssertJ

I can not test the GUI in my application using the AssertJ library. So as not to spread all the code of your program, wrote a test program to show the essence of the problem.

package AssertJ;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class SomeFrame extends JFrame {
    JFrame frame;
    JLabel label1;
    JButton button1;

    public SomeFrame() {
        createGUI();

    }

    public void createGUI() {
        frame = new JFrame("EspiaServer");
        frame.setLayout(new FlowLayout());
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        label1 = new JLabel("Random");
        button1 = new JButton("Click Me!");
        button1.setName("button");
        button1.setSize(200, 200);
        button1.addActionListener(listener);
        frame.add(label1);
        frame.add(button1);
        frame.pack();


    }

    public static void main(String[] args) {
        new SomeFrame();
    }


    ActionListener listener = new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            int i = (int) (Math.random() * 99999) + 0;
            label1.setText(String.valueOf(i));
        }
    };
}

Here's the test for it:

package AssertJ;

import org.assertj.swing.edt.GuiActionRunner;
import org.assertj.swing.fixture.FrameFixture;
import org.junit.Before;
import org.junit.Test;


public class SomeFrameTest {
    private FrameFixture window;

    @Before
    public void setUp() {
        SomeFrame frame = GuiActionRunner.execute(() -> new SomeFrame());
        window = new FrameFixture(frame);
        window.show(); // shows the frame to test
    }


    @Test
    public void createGUI() {
        window.button("button").click();
    }
}

So that's it. The essence of the application. In the frame, there is one button, when pressed, Jlabel changes its value to a random number. The application starts, everything is fine. But when I run the test. He creates the gui of this application and another window in the upper left corner that constantly flashes and twitches. Accordingly, the command window.button ("button").click(); is not satisfied.

After a few seconds, the app throws the exception :

rg.assertj.swing.exception.ComponentLookupException: Unable to find component using matcher org.assertj.swing.core.NameMatcher[name='button', type=javax.swing.JButton, requireShowing=true].

Component hierarchy:
AssertJ.SomeFrame[name='frame0', title='', enabled=true, visible=true, showing=true]
  javax.swing.JRootPane[]
    javax.swing.JPanel[name='null.glassPane']
    javax.swing.JLayeredPane[]
      javax.swing.JPanel[name='null.contentPane']


    at org.assertj.swing.core.BasicComponentFinder.componentNotFound(BasicComponentFinder.java:287)
    at org.assertj.swing.core.BasicComponentFinder.find(BasicComponentFinder.java:272)
    at org.assertj.swing.core.BasicComponentFinder.find(BasicComponentFinder.java:265)
    at org.assertj.swing.core.BasicComponentFinder.findByName(BasicComponentFinder.java:200)
    at org.assertj.swing.fixture.AbstractContainerFixture.findByName(AbstractContainerFixture.java:641)
    at org.assertj.swing.fixture.AbstractContainerFixture.button(AbstractContainerFixture.java:143)
    at AssertJ.SomeFrameTest.createGUI(SomeFrameTest.java:23)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)