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
packagedev.selenium.troubleshooting;importjava.io.IOException;importjava.nio.file.Files;importjava.nio.file.Paths;importjava.util.Arrays;importjava.util.logging.FileHandler;importjava.util.logging.Handler;importjava.util.logging.Level;importjava.util.logging.Logger;importorg.junit.jupiter.api.Assertions;importorg.junit.jupiter.api.Test;importorg.openqa.selenium.manager.SeleniumManager;importorg.openqa.selenium.remote.RemoteWebDriver;publicclassLoggingTest{@Testpublicvoidlogging()throwsIOException{Loggerlogger=Logger.getLogger("");logger.setLevel(Level.FINE);Arrays.stream(logger.getHandlers()).forEach(handler->{handler.setLevel(Level.FINE);});Handlerhandler=newFileHandler("selenium.xml");logger.addHandler(handler);Logger.getLogger(RemoteWebDriver.class.getName()).setLevel(Level.FINEST);Logger.getLogger(SeleniumManager.class.getName()).setLevel(Level.SEVERE);LoggerlocalLogger=Logger.getLogger(this.getClass().getName());localLogger.warning("this is a warning");localLogger.info("this is useful information");localLogger.fine("this is detailed debug information");byte[]bytes=Files.readAllBytes(Paths.get("selenium.xml"));StringfileContent=newString(bytes);Assertions.assertTrue(fileContent.contains("this is a warning"));Assertions.assertTrue(fileContent.contains("this is useful information"));Assertions.assertTrue(fileContent.contains("this is detailed debug information"));}}
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:
importatexitimportloggingimportosimportpytestdeftest_logging():logger=logging.getLogger('selenium')logger.setLevel(logging.DEBUG)log_path="selenium.log"handler=logging.FileHandler(log_path)logger.addHandler(handler)logging.getLogger('selenium.webdriver.remote').setLevel(logging.WARN)logging.getLogger('selenium.webdriver.common').setLevel(logging.DEBUG)logger.info("this is useful information")logger.warning("this is a warning")logger.debug("this is detailed debug information")try:withopen(log_path,'r')asfp:assertlen(fp.readlines())==3finally:atexit.register(delete_path,log_path)defdelete_path(path):os.remove(path)
You must also create and add a log handler (StreamHandler, FileHandler, etc).
.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:
# frozen_string_literal: truerequire'spec_helper'RSpec.describe'Logging'dodescribe'Options'dolet(:file_name){File.expand_path('selenium.log')}after{FileUtils.rm_f(file_name)}it'logs things'dologger=Selenium::WebDriver.loggerlogger.level=:debuglogger.output=file_namelogger.ignore(:jwp_caps,:logger_info)logger.allow(%i[selenium_managerexample_id])logger.warn('this is a warning',id::example_id)logger.info('this is useful information',id::example_id)logger.debug('this is detailed debug information',id::example_id)expect(File.readlines(file_name).grep(/\[:example_id\]/).size).toeq3endendend
packagedev.selenium.troubleshooting;importjava.io.IOException;importjava.nio.file.Files;importjava.nio.file.Paths;importjava.util.Arrays;importjava.util.logging.FileHandler;importjava.util.logging.Handler;importjava.util.logging.Level;importjava.util.logging.Logger;importorg.junit.jupiter.api.Assertions;importorg.junit.jupiter.api.Test;importorg.openqa.selenium.manager.SeleniumManager;importorg.openqa.selenium.remote.RemoteWebDriver;publicclassLoggingTest{@Testpublicvoidlogging()throwsIOException{Loggerlogger=Logger.getLogger("");logger.setLevel(Level.FINE);Arrays.stream(logger.getHandlers()).forEach(handler->{handler.setLevel(Level.FINE);});Handlerhandler=newFileHandler("selenium.xml");logger.addHandler(handler);Logger.getLogger(RemoteWebDriver.class.getName()).setLevel(Level.FINEST);Logger.getLogger(SeleniumManager.class.getName()).setLevel(Level.SEVERE);LoggerlocalLogger=Logger.getLogger(this.getClass().getName());localLogger.warning("this is a warning");localLogger.info("this is useful information");localLogger.fine("this is detailed debug information");byte[]bytes=Files.readAllBytes(Paths.get("selenium.xml"));StringfileContent=newString(bytes);Assertions.assertTrue(fileContent.contains("this is a warning"));Assertions.assertTrue(fileContent.contains("this is useful information"));Assertions.assertTrue(fileContent.contains("this is detailed debug information"));}}
Python has 6 logger levels: CRITICAL, ERROR, WARNING, INFO, DEBUG, and NOTSET.
The default is WARNING
importatexitimportloggingimportosimportpytestdeftest_logging():logger=logging.getLogger('selenium')logger.setLevel(logging.DEBUG)log_path="selenium.log"handler=logging.FileHandler(log_path)logger.addHandler(handler)logging.getLogger('selenium.webdriver.remote').setLevel(logging.WARN)logging.getLogger('selenium.webdriver.common').setLevel(logging.DEBUG)logger.info("this is useful information")logger.warning("this is a warning")logger.debug("this is detailed debug information")try:withopen(log_path,'r')asfp:assertlen(fp.readlines())==3finally:atexit.register(delete_path,log_path)defdelete_path(path):os.remove(path)
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.
usingMicrosoft.VisualStudio.TestTools.UnitTesting;usingOpenQA.Selenium;usingOpenQA.Selenium.Internal.Logging;usingOpenQA.Selenium.Remote;usingSystem;usingSystem.IO;namespaceSeleniumDocs.Troubleshooting{ [TestClass]publicclassLoggingTest{privateconststringfilePath="Selenium.log"; [TestMethod]publicvoidLogging(){Log.SetLevel(LogEventLevel.Trace);Log.Handlers.Add(newFileLogHandler(filePath));Log.SetLevel(typeof(RemoteWebDriver),LogEventLevel.Debug);Log.SetLevel(typeof(SeleniumManager),LogEventLevel.Info);Warn("this is a warning");Info("this is useful information");Debug("this is detailed debug information");using(varfileStream=File.Open(filePath,FileMode.Open,FileAccess.Read,FileShare.ReadWrite)){using(varstreamReader=newStreamReader(fileStream)){varfileLogContent=streamReader.ReadToEnd();StringAssert.Contains(fileLogContent,"this is a warning");StringAssert.Contains(fileLogContent,"this is useful information");StringAssert.Contains(fileLogContent,"this is detailed debug information");}}} [TestCleanup]publicvoidTestCleanup(){// reset log to defaultLog.SetLevel(LogEventLevel.Info).Handlers.Clear().Handlers.Add(newConsoleLogHandler());}// logging is only for internal usage// hacking it via reflectionprivatevoidDebug(stringmessage){LogMessage("Debug",message);}privatevoidWarn(stringmessage){LogMessage("Warn",message);}privatevoidInfo(stringmessage){LogMessage("Info",message);}privatevoidLogMessage(stringmethodName,stringmessage){vargetLoggerMethod=typeof(Log).GetMethod("GetLogger",System.Reflection.BindingFlags.Static|System.Reflection.BindingFlags.NonPublic,newType[]{typeof(Type)});varlogger=getLoggerMethod.Invoke(null,newobject[]{typeof(LoggingTest)});varemitMethod=logger.GetType().GetMethod(methodName);emitMethod.Invoke(logger,newobject[]{message});}}}
Ruby logger has 5 logger levels: :debug, :info, :warn, :error, :fatal.
The default is :info.
# frozen_string_literal: truerequire'spec_helper'RSpec.describe'Logging'dodescribe'Options'dolet(:file_name){File.expand_path('selenium.log')}after{FileUtils.rm_f(file_name)}it'logs things'dologger=Selenium::WebDriver.loggerlogger.level=:debuglogger.output=file_namelogger.ignore(:jwp_caps,:logger_info)logger.allow(%i[selenium_managerexample_id])logger.warn('this is a warning',id::example_id)logger.info('this is useful information',id::example_id)logger.debug('this is detailed debug information',id::example_id)expect(File.readlines(file_name).grep(/\[:example_id\]/).size).toeq3endendend
JavaScript has 9 logger levels: OFF, SEVERE, WARNING, INFO, DEBUG, FINE, FINER, FINEST, ALL.
The default is OFF.
To change the level of the logger:
logger.setLevel(logging.Level.INFO)
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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.
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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
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packagedev.selenium.troubleshooting;importjava.io.IOException;importjava.nio.file.Files;importjava.nio.file.Paths;importjava.util.Arrays;importjava.util.logging.FileHandler;importjava.util.logging.Handler;importjava.util.logging.Level;importjava.util.logging.Logger;importorg.junit.jupiter.api.Assertions;importorg.junit.jupiter.api.Test;importorg.openqa.selenium.manager.SeleniumManager;importorg.openqa.selenium.remote.RemoteWebDriver;publicclassLoggingTest{@Testpublicvoidlogging()throwsIOException{Loggerlogger=Logger.getLogger("");logger.setLevel(Level.FINE);Arrays.stream(logger.getHandlers()).forEach(handler->{handler.setLevel(Level.FINE);});Handlerhandler=newFileHandler("selenium.xml");logger.addHandler(handler);Logger.getLogger(RemoteWebDriver.class.getName()).setLevel(Level.FINEST);Logger.getLogger(SeleniumManager.class.getName()).setLevel(Level.SEVERE);LoggerlocalLogger=Logger.getLogger(this.getClass().getName());localLogger.warning("this is a warning");localLogger.info("this is useful information");localLogger.fine("this is detailed debug information");byte[]bytes=Files.readAllBytes(Paths.get("selenium.xml"));StringfileContent=newString(bytes);Assertions.assertTrue(fileContent.contains("this is a warning"));Assertions.assertTrue(fileContent.contains("this is useful information"));Assertions.assertTrue(fileContent.contains("this is detailed debug information"));}}
By default all logs are sent to sys.stderr. To direct output somewhere else, you need to add a
handler with either a StreamHandler or a FileHandler:
importatexitimportloggingimportosimportpytestdeftest_logging():logger=logging.getLogger('selenium')logger.setLevel(logging.DEBUG)log_path="selenium.log"handler=logging.FileHandler(log_path)logger.addHandler(handler)logging.getLogger('selenium.webdriver.remote').setLevel(logging.WARN)logging.getLogger('selenium.webdriver.common').setLevel(logging.DEBUG)logger.info("this is useful information")logger.warning("this is a warning")logger.debug("this is detailed debug information")try:withopen(log_path,'r')asfp:assertlen(fp.readlines())==3finally:atexit.register(delete_path,log_path)defdelete_path(path):os.remove(path)
By default all logs are sent to System.Console.Error output. To direct output somewhere else, you need to add a handler with a FileLogHandler:
usingMicrosoft.VisualStudio.TestTools.UnitTesting;usingOpenQA.Selenium;usingOpenQA.Selenium.Internal.Logging;usingOpenQA.Selenium.Remote;usingSystem;usingSystem.IO;namespaceSeleniumDocs.Troubleshooting{ [TestClass]publicclassLoggingTest{privateconststringfilePath="Selenium.log"; [TestMethod]publicvoidLogging(){Log.SetLevel(LogEventLevel.Trace);Log.Handlers.Add(newFileLogHandler(filePath));Log.SetLevel(typeof(RemoteWebDriver),LogEventLevel.Debug);Log.SetLevel(typeof(SeleniumManager),LogEventLevel.Info);Warn("this is a warning");Info("this is useful information");Debug("this is detailed debug information");using(varfileStream=File.Open(filePath,FileMode.Open,FileAccess.Read,FileShare.ReadWrite)){using(varstreamReader=newStreamReader(fileStream)){varfileLogContent=streamReader.ReadToEnd();StringAssert.Contains(fileLogContent,"this is a warning");StringAssert.Contains(fileLogContent,"this is useful information");StringAssert.Contains(fileLogContent,"this is detailed debug information");}}} [TestCleanup]publicvoidTestCleanup(){// reset log to defaultLog.SetLevel(LogEventLevel.Info).Handlers.Clear().Handlers.Add(newConsoleLogHandler());}// logging is only for internal usage// hacking it via reflectionprivatevoidDebug(stringmessage){LogMessage("Debug",message);}privatevoidWarn(stringmessage){LogMessage("Warn",message);}privatevoidInfo(stringmessage){LogMessage("Info",message);}privatevoidLogMessage(stringmethodName,stringmessage){vargetLoggerMethod=typeof(Log).GetMethod("GetLogger",System.Reflection.BindingFlags.Static|System.Reflection.BindingFlags.NonPublic,newType[]{typeof(Type)});varlogger=getLoggerMethod.Invoke(null,newobject[]{typeof(LoggingTest)});varemitMethod=logger.GetType().GetMethod(methodName);emitMethod.Invoke(logger,newobject[]{message});}}}
By default, logs are sent to the console in stdout. To store the logs in a file:
# frozen_string_literal: truerequire'spec_helper'RSpec.describe'Logging'dodescribe'Options'dolet(:file_name){File.expand_path('selenium.log')}after{FileUtils.rm_f(file_name)}it'logs things'dologger=Selenium::WebDriver.loggerlogger.level=:debuglogger.output=file_namelogger.ignore(:jwp_caps,:logger_info)logger.allow(%i[selenium_managerexample_id])logger.warn('this is a warning',id::example_id)logger.info('this is useful information',id::example_id)logger.debug('this is detailed debug information',id::example_id)expect(File.readlines(file_name).grep(/\[:example_id\]/).size).toeq3endendend
JavaScript does not currently support sending output to a file.
To send logs to console output:
logging.installConsoleHandler()
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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:
Assertions.assertTrue(fileContent.contains("this is a warning"));
packagedev.selenium.troubleshooting;importjava.io.IOException;importjava.nio.file.Files;importjava.nio.file.Paths;importjava.util.Arrays;importjava.util.logging.FileHandler;importjava.util.logging.Handler;importjava.util.logging.Level;importjava.util.logging.Logger;importorg.junit.jupiter.api.Assertions;importorg.junit.jupiter.api.Test;importorg.openqa.selenium.manager.SeleniumManager;importorg.openqa.selenium.remote.RemoteWebDriver;publicclassLoggingTest{@Testpublicvoidlogging()throwsIOException{Loggerlogger=Logger.getLogger("");logger.setLevel(Level.FINE);Arrays.stream(logger.getHandlers()).forEach(handler->{handler.setLevel(Level.FINE);});Handlerhandler=newFileHandler("selenium.xml");logger.addHandler(handler);Logger.getLogger(RemoteWebDriver.class.getName()).setLevel(Level.FINEST);Logger.getLogger(SeleniumManager.class.getName()).setLevel(Level.SEVERE);LoggerlocalLogger=Logger.getLogger(this.getClass().getName());localLogger.warning("this is a warning");localLogger.info("this is useful information");localLogger.fine("this is detailed debug information");byte[]bytes=Files.readAllBytes(Paths.get("selenium.xml"));StringfileContent=newString(bytes);Assertions.assertTrue(fileContent.contains("this is a warning"));Assertions.assertTrue(fileContent.contains("this is useful information"));Assertions.assertTrue(fileContent.contains("this is detailed debug information"));}}
Because logging is managed by module, instead of working with just "selenium", you can specify
different levels for different modules:
importatexitimportloggingimportosimportpytestdeftest_logging():logger=logging.getLogger('selenium')logger.setLevel(logging.DEBUG)log_path="selenium.log"handler=logging.FileHandler(log_path)logger.addHandler(handler)logging.getLogger('selenium.webdriver.remote').setLevel(logging.WARN)logging.getLogger('selenium.webdriver.common').setLevel(logging.DEBUG)logger.info("this is useful information")logger.warning("this is a warning")logger.debug("this is detailed debug information")try:withopen(log_path,'r')asfp:assertlen(fp.readlines())==3finally:atexit.register(delete_path,log_path)defdelete_path(path):os.remove(path)
.NET logging is managed on a per class level, set the level you want to use on a per-class basis:
usingMicrosoft.VisualStudio.TestTools.UnitTesting;usingOpenQA.Selenium;usingOpenQA.Selenium.Internal.Logging;usingOpenQA.Selenium.Remote;usingSystem;usingSystem.IO;namespaceSeleniumDocs.Troubleshooting{ [TestClass]publicclassLoggingTest{privateconststringfilePath="Selenium.log"; [TestMethod]publicvoidLogging(){Log.SetLevel(LogEventLevel.Trace);Log.Handlers.Add(newFileLogHandler(filePath));Log.SetLevel(typeof(RemoteWebDriver),LogEventLevel.Debug);Log.SetLevel(typeof(SeleniumManager),LogEventLevel.Info);Warn("this is a warning");Info("this is useful information");Debug("this is detailed debug information");using(varfileStream=File.Open(filePath,FileMode.Open,FileAccess.Read,FileShare.ReadWrite)){using(varstreamReader=newStreamReader(fileStream)){varfileLogContent=streamReader.ReadToEnd();StringAssert.Contains(fileLogContent,"this is a warning");StringAssert.Contains(fileLogContent,"this is useful information");StringAssert.Contains(fileLogContent,"this is detailed debug information");}}} [TestCleanup]publicvoidTestCleanup(){// reset log to defaultLog.SetLevel(LogEventLevel.Info).Handlers.Clear().Handlers.Add(newConsoleLogHandler());}// logging is only for internal usage// hacking it via reflectionprivatevoidDebug(stringmessage){LogMessage("Debug",message);}privatevoidWarn(stringmessage){LogMessage("Warn",message);}privatevoidInfo(stringmessage){LogMessage("Info",message);}privatevoidLogMessage(stringmethodName,stringmessage){vargetLoggerMethod=typeof(Log).GetMethod("GetLogger",System.Reflection.BindingFlags.Static|System.Reflection.BindingFlags.NonPublic,newType[]{typeof(Type)});varlogger=getLoggerMethod.Invoke(null,newobject[]{typeof(LoggingTest)});varemitMethod=logger.GetType().GetMethod(methodName);emitMethod.Invoke(logger,newobject[]{message});}}}
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:
# frozen_string_literal: truerequire'spec_helper'RSpec.describe'Logging'dodescribe'Options'dolet(:file_name){File.expand_path('selenium.log')}after{FileUtils.rm_f(file_name)}it'logs things'dologger=Selenium::WebDriver.loggerlogger.level=:debuglogger.output=file_namelogger.ignore(:jwp_caps,:logger_info)logger.allow(%i[selenium_managerexample_id])logger.warn('this is a warning',id::example_id)logger.info('this is useful information',id::example_id)logger.debug('this is detailed debug information',id::example_id)expect(File.readlines(file_name).grep(/\[:example_id\]/).size).toeq3endendend
# frozen_string_literal: truerequire'spec_helper'RSpec.describe'Logging'dodescribe'Options'dolet(:file_name){File.expand_path('selenium.log')}after{FileUtils.rm_f(file_name)}it'logs things'dologger=Selenium::WebDriver.loggerlogger.level=:debuglogger.output=file_namelogger.ignore(:jwp_caps,:logger_info)logger.allow(%i[selenium_managerexample_id])logger.warn('this is a warning',id::example_id)logger.info('this is useful information',id::example_id)logger.debug('this is detailed debug information',id::example_id)expect(File.readlines(file_name).grep(/\[:example_id\]/).size).toeq3endendend
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