vaadin-framework/uitest/src/test/java/com/vaadin/tests/themes/ThemeChangeOnTheFlyTest.java

package com.vaadin.tests.themes;

import static org.hamcrest.CoreMatchers.containsString;
import static org.hamcrest.MatcherAssert.assertThat;

import java.io.IOException;

import org.junit.Test;
import org.openqa.selenium.By;
import org.openqa.selenium.WebElement;

import com.vaadin.testbench.elements.ButtonElement;
import com.vaadin.tests.tb3.MultiBrowserTest;

public class ThemeChangeOnTheFlyTest extends MultiBrowserTest {

    @Test
    public void injectedStyleAndThemeChange() throws IOException {
        openTestURL();
        $(ButtonElement.class).caption("Inject blue background").first()
                .click();
        changeTheme("runo");
        compareScreen("runo-blue-background");
    }

    @Test
    public void reindeerToOthers() throws IOException {
        openTestURL();
        compareScreen("reindeer");

        changeThemeAndCompare("runo");
        changeThemeAndCompare("chameleon");
        changeThemeAndCompare("base");

    }

    @Test
    public void runoToReindeer() throws IOException {
        openTestURL("theme=runo");
        compareScreen("runo");
        changeThemeAndCompare("reindeer");
    }

    @Test
    public void reindeerToNullToReindeer() throws IOException {
        openTestURL();

        changeTheme("null");
        changeThemeAndCompare("reindeer");
    }

    private void changeThemeAndCompare(String theme) throws IOException {
        changeTheme(theme);
        compareScreen(theme);
    }

    private void changeTheme(String theme) {
        $(ButtonElement.class).id(theme).click();
        if (theme.equals("null")) {
            waitForThemeToChange("");
            assertOverlayTheme("");
        } else {
            waitForThemeToChange(theme);
            assertOverlayTheme(theme);
        }
    }

    private void assertOverlayTheme(String theme) {
        final WebElement overlayContainerDiv = findElement(
                By.xpath("//div[contains(@class,'v-overlay-container')]"));
        String overlayClass = overlayContainerDiv.getAttribute("class").trim();

        assertThat(overlayClass, containsString(theme));
    }

}