It is not always obvious the root cause of errors in Selenium.
The most common Selenium-related error is a result of poor synchronization.
Read about Waiting Strategies. If you aren’t sure if it
is a synchronization strategy you can try temporarily hard coding a large sleep
where you see the issue, and you’ll know if adding an explicit wait can help.
Note that many errors that get reported to the project are actually caused by
issues in the underlying drivers that Selenium sends the commands to. You can rule
out a driver problem by executing the command in multiple browsers.
If you have questions about how to do things, check out the Support options
for ways get assistance.
If you think you’ve found a problem with Selenium code, go ahead and file a
Bug Report
on GitHub.
1 - Understanding Common Errors
How to get deal with various problems in your Selenium code.
Invalid Selector Exception
CSS and XPath Selectors are sometimes difficult to get correct.
Likely Cause
The CSS or XPath selector you are trying to use has invalid characters or an invalid query.
An element goes stale when it was previously located, but can not be currently accessed.
Elements do not get relocated automatically; the driver creates a reference ID for the element and
has a particular place it expects to find it in the DOM. If it can not find the element
in the current DOM, any action using that element will result in this exception.
Common Causes
This can happen when:
You have refreshed the page, or the DOM of the page has dynamically changed.
You have navigated to a different page.
You have switched to another window or into or out of a frame or iframe.
Common Solutions
The DOM has changed
When the page is refreshed or items on the page have moved around, there is still
an element with the desired locator on the page, it is just no longer accessible
by the element object being used, and the element must be relocated before it can be used again.
This is often done in one of two ways:
Always relocate the element every time you go to use it. The likelihood of
the element going stale in the microseconds between locating and using the element
is small, though possible. The downside is that this is not the most efficient approach,
especially when running on a remote grid.
Wrap the Web Element with another object that stores the locator, and caches the
located Selenium element. When taking actions with this wrapped object, you can
attempt to use the cached object if previously located, and if it is stale, exception
can be caught, the element relocated with the stored locator, and the method re-tried.
This is more efficient, but it can cause problems if the locator you’re using
references a different element (and not the one you want) after the page has changed.
The Context has changed
Element objects are stored for a given context, so if you move to a different context —
like a different window or a different frame or iframe — the element reference will
still be valid, but will be temporarily inaccessible. In this scenario, it won’t
help to relocate the element, because it doesn’t exist in the current context.
To fix this, you need to make sure to switch back to the correct context before using the element.
The Page has changed
This scenario is when you haven’t just changed contexts, you have navigated to another page
and have destroyed the context in which the element was located.
You can’t just relocate it from the current context,
and you can’t switch back to an active context where it is valid. If this is the reason
for your error, you must both navigate back to the correct location and relocate it.
1.1 - Unable to Locate Driver Error
Troubleshooting missing path to driver executable.
Historically, this is the most common error beginning Selenium users get
when trying to run code for the first time:
The path to the driver executable must
be set by the webdriver.chrome.driver system property;
for more information, see https://chromedriver.chromium.org/.
The latest version can be downloaded from https://chromedriver.chromium.org/downloads
The executable chromedriver needs to be available in the path.
The file geckodriver does not exist. The driver can be downloaded at https://github.com/mozilla/geckodriver/releases"
Unable to locate the chromedriver executable;
Likely cause
Through WebDriver, Selenium supports all major browsers.
In order to drive the requested browser, Selenium needs to
send commands to it via an executable driver.
This error means the necessary driver could not be
found by any of the means Selenium attempts to use.
Possible solutions
There are several ways to ensure Selenium gets the driver it needs.
Use the latest version of Selenium
As of Selenium 4.6, Selenium downloads the correct driver for you.
You shouldn’t need to do anything. If you are using the latest version
of Selenium and you are getting an error,
please turn on logging
and file a bug report with that information.
If you want to read more information about how Selenium manages driver downloads for you,
you can read about the Selenium Manager.
This is a flexible option to change location of drivers without having to update your code,
and will work on multiple machines without requiring that each machine put the
drivers in the same place.
You can either place the drivers in a directory that is already listed in PATH,
or you can place them in a directory and add it to PATH.
To see what directories are already on PATH, open a Terminal and execute:
echo$PATH
If the location to your driver is not already in a directory listed,
you can add a new directory to PATH:
You can test if it has been added correctly by checking the version of the driver:
chromedriver --version
To see what directories are already on PATH, open a Command Prompt and execute:
echo %PATH%
If the location to your driver is not already in a directory listed,
you can add a new directory to PATH:
setx PATH "%PATH%;C:\WebDriver\bin"
You can test if it has been added correctly by checking the version of the driver:
chromedriver.exe --version
Specify the location of the driver
If you cannot upgrade to the latest version of Selenium, you
do not want Selenium to download drivers for you, and you can’t figure
out the environment variables, you can specify the location of the driver in the Service object.
Specifying the location in the code itself has the advantage of not needing
to figure out Environment Variables on your system, but has the drawback of
making the code less flexible.
Driver management libraries
Before Selenium managed drivers itself, other projects were created to
do so for you.
If you can’t use Selenium Manager because you are using
an older version of Selenium (please upgrade),
or need an advanced feature not yet implemented by Selenium Manager,
you might try one of these tools to keep your drivers automatically updated:
Nota: O Opera driver já não inclui as funcionalidades mais recentes do Selenium e oficialmente deixou de ser suportado.
2 - Logging Selenium commands
Getting information about Selenium execution.
Turning on logging is a valuable way to get extra information that might help you determine
why you might be having a problem.
Getting a logger
Java logs are typically created per class. You can work with the default logger to
work with all loggers. To filter out specific classes, see Filtering
Java Logging is not exactly straightforward, and if you are just looking for an easy way
to look at the important Selenium logs,
take a look at the Selenium Logger project
Python logs are typically created per module. You can match all submodules by referencing the top
level module. So to work with all loggers in selenium module, you can do this:
.NET logger is managed with a static class, so all access to logging is managed simply by referencing Log from the OpenQA.Selenium.Internal.Logging namespace.
If you want to see as much debugging as possible in all the classes,
you can turn on debugging globally in Ruby by setting $DEBUG = true.
For more fine-tuned control, Ruby Selenium created its own Logger class to wrap the default Logger class.
This implementation provides some interesting additional features.
Obtain the logger directly from the #loggerclass method on the Selenium::WebDriver module:
Things get complicated when you use PyTest, though. By default, PyTest hides logging unless the test
fails. You need to set 3 things to get PyTest to display logs on passing tests.
To always output logs with PyTest you need to run with additional arguments.
First, -s to prevent PyTest from capturing the console.
Second, -p no:logging, which allows you to override the default PyTest logging settings so logs can
be displayed regardless of errors.
So you need to set these flags in your IDE, or run PyTest on command line like:
pytest -s -p no:logging
Finally, since you turned off logging in the arguments above, you now need to add configuration to
turn it back on:
logging.basicConfig(level=logging.WARN)
.NET has 6 logger levels: Error, Warn, Info, Debug, Trace and None. The default level is Info.
Things are logged as warnings if they are something the user needs to take action on. This is often used
for deprecations. For various reasons, Selenium project does not follow standard Semantic Versioning practices.
Our policy is to mark things as deprecated for 3 releases and then remove them, so deprecations
may be logged as warnings.
Java logs actionable content at logger level WARN
Example:
May 08, 2023 9:23:38 PM dev.selenium.troubleshooting.LoggingTest logging
WARNING: this is a warning
Python logs actionable content at logger level — WARNING
Details about deprecations are logged at this level.
Example:
WARNING selenium:test_logging.py:23 this is a warning
.NET logs actionable content at logger level Warn.
Example:
11:04:40.986 WARN LoggingTest: this is a warning
Ruby logs actionable content at logger level — :warn.
Details about deprecations are logged at this level.
For example:
2023-05-08 20:53:13 WARN Selenium [:example_id] this is a warning
Because these items can get annoying, we’ve provided an easy way to turn them off, see filtering section below.
Content Help
Note:
This section needs additional and/or updated content
This is the default level where Selenium logs things that users should be aware of but do not need to take actions on.
This might reference a new method or direct users to more information about something
Java logs useful information at logger level INFO
Example:
May 08, 2023 9:23:38 PM dev.selenium.troubleshooting.LoggingTest logging
INFO: this is useful information
Python logs useful information at logger level — INFO
Example:
INFO selenium:test_logging.py:22 this is useful information
.NET logs useful information at logger level Info.
Example:
11:04:40.986 INFO LoggingTest: this is useful information
Ruby logs useful information at logger level — :info.
Example:
2023-05-08 20:53:13 INFO Selenium [:example_id] this is useful information
Logs useful information at level: INFO
Content Help
Note:
This section needs additional and/or updated content
Java logging is managed on a per class level, so
instead of using the root logger (Logger.getLogger("")), set the level you want to use on a per-class
basis:
Ruby’s logger allows you to opt in (“allow”) or opt out (“ignore”) of log messages based on their IDs.
Everything that Selenium logs includes an ID. You can also turn on or off all deprecation notices by
using :deprecations.
These methods accept one or more symbols or an array of symbols:
Interessado no Selenium 4? Veja este guia para realizar o upgrade para a ultima versão!
Atualizar para o Selenium 4 deve ser um processo sem dificuldades se você estiver usando uma das linguagens oficialmente suportadas
(Ruby, JavaScript, C#, Python, and Java). Pode haver alguns casos em que alguns problemas podem acontecer,
este guia irá ajudar você a resolvê-los. Vamos passar as etapas para atualizar as dependências do seu
projeto e entender as depreciações e também as mudanças trazidas pela versão atualizada.
Estas são as etapas que seguiremos para atualizar para o Selenium 4:
Preparando nosso código de teste
Atualizando as dependências
Possíveis erros e mensagens de suspensão de uso
Nota: enquanto as versões do Selenium 3.x estavam sendo desenvolvidas, foi implementado o suporte padrão para W3C WebDriver.
Este novo protocolo e o legado JSON Wire Protocol foram suportados. Através da versão 3.11, o código do Selenium passou a ser compátivel com o nível 1 da especificação W3C.
A compatibilidade do código W3C na ultima versão do Selenium 3 irá funcionar como esperado na versão 4.
Preparando nosso código de teste
Selenium 4 remove suporte para protocolos legados e usa o W3C Webdriver por padrão.
Para a maioria das coisas, essa implementação não irá afetar usuários finais.
As maiores exeções são Capabilities e a classe Actions.
Recursos
Se os recursos de teste não forem estruturados para serem compatíveis com W3C, pode fazer com que uma sessão não
seja iniciada. Aqui está a lista de recursos padrão do W3C WebDriver:
browserName
browserVersion (replaces version)
platformName (replaces platform)
acceptInsecureCerts
pageLoadStrategy
proxy
timeouts
unhandledPromptBehavior
Uma lista atualizada de recursos padrão pode ser encontrada aqui:
W3C WebDriver.
Qualquer recurso que não esteja incluido na lista acima, precisa ser incluido um prefixo de fornecedor.
Isso se aplica aos recursos específicos do navegador, bem como aos recursos específicos do fornecedor da nuvem.
Por exemplo, se o seu fornecedor de nuvem usa os recursos build e name para seus testes, você precisa
envolvê-los em um bloco cloud: options (verifique com seu fornecedor de nuvem o prefixo apropriado).
O utilitário para localizar elementos no Java (interfaces FindsBy) foram removidos
visto que se destinavam apenas a uso interno. Os exemplos de código a seguir explicam isso melhor.
Verifique as subseções abaixo para isntalar o Selenium 4 e atualizar as dependências do seu projeto
Java
O processo de atualização do Selenium depende de qual ferramenta de compilação está sendo usada. Vamos mostrar as mais comuns para Java, como Maven e Gradle. A versão minínma do Java ainda é 8.
Maven
Antes
<dependencies><!-- more dependencies ... --><dependency><groupId>org.seleniumhq.selenium</groupId><artifactId>selenium-java</artifactId><version>3.141.59</version></dependency><!-- more dependencies ... --></dependencies>
Depois
<dependencies><!-- more dependencies ... --><dependency><groupId>org.seleniumhq.selenium</groupId><artifactId>selenium-java</artifactId><version>4.4.0</version></dependency><!-- more dependencies ... --></dependencies>
Após realizar a mudança, você pode executar mvn clean compile no mesmo diretório, onde o
arquivo pom.xml está.
Gradle
Antes
plugins {
id 'java'
}
group 'org.example'
version '1.0-SNAPSHOT'
repositories {
mavenCentral()
}
dependencies {
testImplementation 'org.junit.jupiter:junit-jupiter-api:5.7.0'
testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.7.0'
implementation group: 'org.seleniumhq.selenium', name: 'selenium-java', version: '3.141.59'
}
test {
useJUnitPlatform()
}
Depois
plugins {
id 'java'
}
group 'org.example'
version '1.0-SNAPSHOT'
repositories {
mavenCentral()
}
dependencies {
testImplementation 'org.junit.jupiter:junit-jupiter-api:5.7.0'
testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.7.0'
implementation group: 'org.seleniumhq.selenium', name: 'selenium-java', version: '4.4.0'
}
test {
useJUnitPlatform()
}
Após realizar a mudança, você pode executar ./gradlew clean build no mesmo diretório onde o arquivo build.gradleestá.
Para verifica todas as versões do Java, você pode ir até MVNRepository.
C#
O local para obter atualizações para Selenium 4 em C# é NuGet
Dentro do pacaote Selenium.WebDriver você pode seguir as instruções para atualizar para ultima versão.
Dentro do Visual Studio, através do NuGet Package Manager você pode executar:
A mudança mais importante para usar o Python é a versão minima requerida. Para Selenium 4 a versão miníma requerida será Python3.7 ou superior.
Mais detalhes podem ser encontrados aqui:Python Package Index.
Para atualizar através da linha de comando, você pode executar:
pip install selenium==4.4.3
Ruby
Detalhes para atualizar para o Selenium 4 podem ser vistos aqui:
selenium-webdriver gem in RubyGems
Para instalar a ultima versão, você pode executar:
gem install selenium-webdriver
Para adicioná-lo ao seu Gemfile:
gem 'selenium-webdriver', '~> 4.4.0'
JavaScript
O pacote selenium-webdriver pode ser encontrado pelo Node package manager,
npmjs. Selenium 4 pode ser encontrado aqui.
Para instalar, você pode executar:
npm install selenium-webdriver
Ou, atualize o seu package.json e execute npm install:
Aqui temos um conjunto de exemplos de código que o ajudarão a superar as mensagens de descontinuação, que você pode
encontrar após atualizar para o Selenium 4.
Java
Waits e Timeout
Os parametros que eram esperados de ser recebidos em um Timeout trocaram de (long time, TimeUnit unit) para
o (Duration duration).
As esperas(waits) também esperam parâmetros diferentes agora. O WebDriverWait
agora espera uma Duration em vez de um tempo limite long em segundos e milissegundos.
Os métodos utilitários withTimeout e pollingEvery do FluentWait passaram do
(long time, TimeUnit unit) para o (Duration duration).
A fusão de recursos não estã mais alterando o objeto de invocação
Antes era possível fundir um conjunto diferente de recursos em outro counjunto, e isso
alterava o objeto de chamada. Agora, o resultado da operação de fusão precisa ser atribuído.
Antes
MutableCapabilitiescapabilities=newMutableCapabilities();capabilities.setCapability("platformVersion","Windows 10");FirefoxOptionsoptions=newFirefoxOptions();options.setHeadless(true);options.merge(capabilities);//Como resultado, o objeto `options` estava sendo modificado.
Depois
MutableCapabilitiescapabilities=newMutableCapabilities();capabilities.setCapability("platformVersion","Windows 10");FirefoxOptionsoptions=newFirefoxOptions();options.setHeadless(true);options=options.merge(capabilities);// O resultado da chamada `merge` precisa ser atribuído a um objeto.
Firefox Legacy
Antes do GeckoDriver existir, o projeto Selenium tinha uma implementação de driver para automatizar
o Firefox(versão<48). Entretanto, esta implementação não é mais necessária, pois não funciona
nas versões mais recentes do Firefox. Para evitar graves problemas ao atualizar para o Selenium 4,
a opção setLegacy será mostrada como obsoleta. A recomendação é parar de utilizar a implementação
antiga e depender apenas do GeckoDriver. O código a seguir mostrará a linha setLegacy obsoleta após
atualizar.
Em vez dela, AddAdditionalOption é recomendada. Aqui está um exemplo mostrando isso:
Antes
var browserOptions = new ChromeOptions();
browserOptions.PlatformName = "Windows 10";
browserOptions.BrowserVersion = "latest";
var cloudOptions = new Dictionary<string, object>();
browserOptions.AddAdditionalCapability("cloud:options", cloudOptions, true);
Depois
var browserOptions = new ChromeOptions();
browserOptions.PlatformName = "Windows 10";
browserOptions.BrowserVersion = "latest";
var cloudOptions = new Dictionary<string, object>();
browserOptions.AddAdditionalOption("cloud:options", cloudOptions);
Python
executable_path foi descontinuada, por favor, passe um Service object
No Selenium 4, você precisara definir o executable_path a partir de um objeto Service para evitar avisos de depreciação.
(Ou não defina o caminho e, em vez disso, certifique-se de que o driver que você precisa esteja no System PATH.)
Passamos pelas principais mudanças a serem levadas em consideração ao atualizar para o Selenium 4.
Cobrimos os diferentes aspectos a serem cobertos quando o código de teste é preparado para a atualização, incluindo
sugestões sobre como evitar possíveis problemas que podem aparecer ao usar a nova versão do
Selenium. Para finalizar, também abordamos um conjunto de possíveis problemas com os quais você pode se deparar depois
da atualização e compartilhamos possíveis correções para esses problemas.
