FluentList leads to StaleElementReferenceException

[fedotxxl]

Hello. I've got a table with rows.

        @FindBy(css = ".t-collaborator")
        private FluentList<Collaborator> collaborators;

My test does the following:

1. Check rows content
2. Add one more row
3. Check rows content

On step 3 I've got org.openqa.selenium.StaleElementReferenceException exception. I tried to use reset() with no luck. How can I reset fluent list state?

[slawekradzyminski]

Hi fedotxxl. Do you use the latest version? If yes can you please share piece of code which triggers it?

[fedotxxl]

I use version 3.8.1 because of Java 8.

Here is sample code:

public class Main {
    public static class RepoCollaborationsTabComponent extends FluentWebElement {

        @FindBy(css = "table.t-collaborators")
        private RepoCollaborationsTabComponent.Table table;

        public void assertCollaborators(List<RepoCollaborationsTabComponent.Collaborator> collaborators) {
            assertThat(table.getCollaboratorsData()).isEqualTo(collaborators);
        }
    }

    public static class Table extends FluentWebElement {

        @FindBy(css = ".t-collaborator")
        private FluentList<RepoCollaborationsTabComponent.Table.Collaborator> collaborators;

        public List<RepoCollaborationsTabComponent.Collaborator> getCollaboratorsData() {
            return collaborators.stream()
                    .map(RepoCollaborationsTabComponent.Table.Collaborator::getData)
                    .collect(Collectors.toList());
        }

        public static class Collaborator extends FluentWebElement {

            @FindBy(css = ".t-collaborator--email")
            private FluentWebElement email;

            @FindBy(css = ".t-collaborator--invite-not-accepted")
            private FluentWebElement inviteNotAcceptedIcon;
        }
    }

}

When I call assertCollaborators the first time it works as expected. When I call it after table change (adding new collaborator) table.collaborators contains the previous list of collaborators and org.openqa.selenium.StaleElementReferenceException is thrown.

[slawekradzyminski]

Thanks @fedotxxl for report. Improving stream() may not be easy, but I'll try in free time.

Probably the same root cause as #787

[famoser]

Failing test case which exposes the root cause (to be placed within WaitComponentsListTest):

@Test
void shouldReturnActualValueFromTheInternalChangedList() {
	goTo(ELEMENT_REPLACE_URL);
	await().until(rowsListPage.getComponentsList()).size(2);
	assertThat(rowsListPage.getComponentsList().size()).isEqualTo(2);
	await().until(rowsListPage.getComponentsList()).size(4);
	assertThat(rowsListPage.getComponentsList().size()).isEqualTo(4);
}

The issue seems to be that FluentList maintains internal list state (within DelegatingList) which is resolved once, but then not updated. Using any method which uses the internal FluentList state (instead of going over LocatorProxies) may return an outdated result.

This leads to the following failing use cases:

• Access list.textContents(), navigate, access list.textContents() again -> StaleElementReferenceException
• Using list.size(), navigate, list.size() -> the second call may returns a wrong result

For a list of affected use cases see the methods implemented in the interface FluentList using stream() (as stream will always access the internal FluentList state, instead of using the LocatorProxies).