where does selenium run? - selenium

Question

I am super confused with selenium.
Completely new to automated testing and struggling to get a foothold with selenium.
http://www.seleniumhq.org/projects/webdriver/
I get the concept of writing tests and have done a few with in angular with protractor, but i need to use selenium for a particular project and not sure where to start.
To start with I just want to be able to write some simple client side tests, but i have no idea where to start with on Selenium, i read their docs but not really any the wiser..

Answer 1

A webdriver test is just a script, written in one of many compatible languages (java, python, etc). The script runs on any machine. During development it will typically run on your local machine, but eventually your test could run on a continuous integration server.
Webdriver has two modes of operation: it can open a browser on the same machine that the script is running, or it can send a request to a selenium grid hub, which will open a browser on one of its nodes.
As a simple example, here is a complete working example of a selenium test in python (taken from python selenium bindings Getting Started page):
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
driver = webdriver.Firefox()
driver.get("http://www.python.org")
assert "Python" in driver.title
elem = driver.find_element_by_name("q")
elem.send_keys("pycon")
elem.send_keys(Keys.RETURN)
assert "No results found." not in driver.page_source
driver.close()
If you have python and the selenium libraries installed, you can save this file to "example_test.py" and then run it from a command prompt with python example_test.py
Here's a similar test, this one in javascript, taken from the WebDriverJS User's Guide. You would run it the same way you run any javascript program.
var webdriver = require('selenium-webdriver');
var driver = new webdriver.Builder().
withCapabilities(webdriver.Capabilities.chrome()).
build();
driver.get('http://www.google.com');
driver.findElement(webdriver.By.name('q')).sendKeys('webdriver');
driver.findElement(webdriver.By.name('btnG')).click();
driver.wait(function() {
return driver.getTitle().then(function(title) {
return title === 'webdriver - Google Search';
});
}, 1000);
driver.quit();

Answer 2

To give you an organic answer to your question, when you run a selenium Firefox browser test, it starts a local ad-hoc "Selenium grid hub listener" on a port like 30005 or something at the start of the test. Then, the code that you write talks to that local port in JSON format by sending local http requests to localhost:30005 . The "Grid hub" listening on that port knows how to talk to your local web browser and controls it by answering commands passed through that port. At the end of the test, the "selenium grid hub listener port" closes.
If you do some reading and try to understand how the "Selenium Grid Hub" works and also learn about "WebDriver Wire Protocol", then it might help you start understanding what I explained above.

Answer 3

Always read the official Selenium docs for references, but if you are using Java, you can get a head-start by using the Conductor framework
It's a Java specific DSL, so won't work with any other.
A test would look like this:
#Config(url="http://google.com", browser=Browsers.CHROME)
public class MyTest {
#Test
public void testGoogle() {
// a quick google search
setText(By.name("q"), "something")
.click("[name='btnG']");
}
}