Selenium: wait for server response just long enough? - selenium

Question

We have large suites of selenium scripts and some of the tests are "unstable": On the CI-builds they fail but on the dev-machines they are ok.
We assume that the reason is in performance: the CI-builds are slower than the dev-machines and our application blocks any interaction with the web-app directly after an action until the server response comes back.
This brings me to the question:
How can the client know how long the server might take?
We can wait after each click for a long time -> but this will slow down the test-suite heavily.
Is there a trick to wait just long enough ?
Since our suites are so large, I do not want to maintain/treat this in each and every test-case but generically in test-framework or on server side.
I dont have much technical experience with selenium, but this sounds more like a conceptual problem.

Answer 1

This is what you can do (at a high level).
On the client you can call your API. When the API completes (whether success or fail) you can set a global variable stating that the API has completed.
$.getJSON('/some/endpoint.xhtml', {
someParam: someVar
})
.done(function (data) {
// do work
})
.fail(function (data) {
// do error handling
})
.always(function(data) {
// window.testVars will need to be initialized earlier
// like so : window.testVars = { completedEndoint = 0 };
window.testVars.completedEndpoint++;
});
Then in the Java Selenium code you have access to those variables through a JavascriptExecutor driver.
private static Map<String, Object> getState(WebDriver driver)
{
Map<String, Object> map = (Map<String,Object>)((JavascriptExecutor)driver).executeScript("return window.testVars");
return map;
}
Then in your test you can use:
Map<String,Object> defState = initializeState(driver);
performUseCaseToCallTheEndpoint();
ExpectedCondition<Boolean> condition = new ExpectedCondition<Boolean>()
{
#Override
public Boolean apply(WebDriver driver)
{
Map<String,Object> curState = getState(driver);
if(curState.get("completedEndpoint") > defState get("completedEndpoint"))
{
return true;
}
else
{
return false;
}
}
};
WebDriverWait wait = new WebDriverWait(driver, 60);
wait.until(condition);
This should get you started.

Answer 2

In the class, you could have fields
public int startTime;
public int stopTime;
public int averageResponseTime = 2000;
Here, set averageResponseTime to the maximum time you are willing to wait for a response (in this example, 2000 milliseconds)
In your #Before/testSetup method:
// set the startime for the test
startTime = new Date();
In your #After/tearDown method:
// set the stopTime
stopTime = new Date();
// calculate how long it took
int duration = stopTime - startTime;
// average out the response time
averageResponseTime = (averageResponseTime + duration)/2;
In your test, instantiate a new wait, passing in averageResponseTime as the waitTimeout
WebDriverWait wait = new WebDriverWait(driver, averageResponseTime); wait.until(expectedCondition);
After the first test (or so) the timeout will get closer and closer to the average time the server actually takes to respond.