Why do Selenium tests behave different on different machines? - powershell

Question

I couldn't find much information on Google regarding this topic. Below, I have provided three results from the same Selenium tests. Why am I getting different results when running the tests from different places?
INFO:
So our architecture: Bitbucket, Bamboo Stage 1 (Build, Deploy to QA), Bamboo Stage 2 (start Amazon EC2 instance "Test", run tests from Test against recently deployed QA)
Using Chrome Webdriver.
For all three of the variations I am using the same QA URL that our application is deployed on.
I am running all tests Parallelizable per fixture
The EC2 instance is running Windows Server 2012 R2 with the Chrome browser installed
I have made sure that the test solution has been properly deployed to the EC2 "test" instance. It is indeed the exact same solution and builds correctly.
First, Local:
Second, from EC2 Via SSM Script that invokes the tests:
Note that the PowerShell script calls the nunit3-console.exe just like it would be utilized in my third example using the command line.
Lastly, RDP in on EC2 and run tests from the command line:
This has me perplexed... Any reasons why Selenium is running different on different machines?

Answer 1

This really should be a comment, but I can't comment yet so...
I don't know enough about the application you are testing to say for sure, but this seems like something I've seen testing the application I'm working on.
I have seen two issues. First, Selenium is checking for the element before it's created. Sometimes it works and sometimes it fails, it just depends on how quickly the page loads when the test runs. There's no rhyme or reason to it. Second, the app I'm testing is pretty dumb. When you touch a field, enter data and move on to the next, it, effectively, posts all editable fields back to the database and refreshes all the fields. So, Selenium enters the value, moves to the next field and pops either a stale element error or can't find element error depending on when in the post/refresh cycle it attempts to interact with the element.
The solution I have found is moderately ugly, I tried the wait until, but because it's the same element name, it's already visible and is grabbed immediately which returns a stale element. As a result, the only thing that I have found is that by using explicit waits between calls, I can get it to run correctly consistently. Below is an example of what I have to do with the app I'm testing. (I am aware that I can condense the code, I am working within the style manual for my company)
Thread.Sleep(2000);
By nBaseLocator = By.XPath("//*[#id='attr_seq_1240']");
IWebElement baseRate = driver.FindElement(nBaseLocator);
baseRate.SendKeys(Keys.Home + xBaseRate + Keys.Tab);
If this doesn't help, please tell us more about the app and how it's functioning so we can help you find a solution.

Answer 2

#Florent B. Thank you!
EDIT: This ended up not working...
The tests are still running different when called remotely with a powershell script. But, the tests are running locally on both the ec2 instance and my machine correctly.
So the headless command switch allowed me to replicate my failed tests locally.
Next I found out that a headless chrome browser is used during the tests when running via script on an EC2 instance... That is automatic, so the tests where indeed running and the errors where valid.
Finally, I figured out that the screen size is indeed the culprit as it was stuck to a size of 600/400 (600/400?)
So after many tries, the only usable screen size option for Windows, C# and ChromeDriver 2.32 is to set your webDriver options when you initiate you driver:
ChromeOptions chromeOpt = new ChromeOptions();
chromeOpt.AddArguments("--headless");
chromeOpt.AddArgument("--window-size=1920,1080");
chromeOpt.AddArguments("--disable-gpu");
webDriver = new ChromeDriver(chromeOpt);
FINISH EDIT:
Just to update
Screen size is large enough.
Still attempting to solve the issue. Anyone else ran into this?
AWS SSM Command -> Powershell -> Run Selenium Tests with Start-Process -> Any test that requires an element fails because ElementNotFound or ElementNotVisible exceptions.
Using POM for tests. FindsBy filter in c# is not finding elements.
Running tests locally on EC2 run fine from cmd, powershell and Powershell ISE.
The tests do not work correctly when executing with the AWS SSM Command. Cannot find any resources to fix problem.