Change to desiredCapabilities in beforeEach not reflecting - nightwatch.js

Question

I am trying to record all browser request and responses. This can be done via browsermob-proxy api's.
For this, I have to change desired capabilities and change httpProxy for browser.
In beforeEach at global or file level, I am trying to change this. Though it reflects in browser object, actual browser is not initiated with those settings.
Simple example:
globalhook file
module.exports = {
before : function (done) {
},
beforeEach: function(browser, done){
browser.options.desiredCapabilities = {
"browserName": "chrome",
"proxy": {
"proxyType": "manual",
"httpProxy": "127.0.0.1:" + someport,
"sslProxy": "127.0.0.1:" + someport
},
"javascriptEnabled": true,
"acceptSslCerts": true,
}
done()
},
afterEach: function(browser, done){
//some code
}
after : function (done) {
//some code
},
}
If i change desired capabilities in before hook, chrome browser is taking those changes. Problem is with beforeEach [global, file level].
Further debugging, I've found setCapabilities function is run just before beforeEach Hook.
Could anyone please have a look or suggest if I am doing something wrong.

Answer 1

Thanks for moving the issue here.
The issue is that the desiredCapabilities are applied to a browser session.
beforeEach and afterEach run on the same browser session therefore any change in the desiredCapabilities won't be applied unless the session is restarted.
If you need to dynamically change the desiredCapabilities you have to structure your tests in the different way, e.g. split your tests in separate test classes

Answer 2

First of all, you probably want to use before() hook instead of beforeEach(), since beforeEach() will run before each test case and you won't be able to modify already started browser session. before() will run before browser session is initiated.
To solve your issue you need to define desiredCapabilities property on your test run module and in case you need to set some dynamic values, use before() hook to modify that object:
module.exports = {
desiredCapabilities: {
"browserName": "chrome",
"proxy": {
"proxyType": "manual",
"httpProxy": "127.0.0.1",
"sslProxy": "127.0.0.1"
},
"javascriptEnabled": true,
"acceptSslCerts": true,
},
before: function(client, done) {
this.desiredCapabilities.proxy.sslProxy = '127.0.0.1' + someport;
done();
}
}
I've searched official docs on this feature but couldn't find anything, though we used this in our tests and it worked well.
Update:
Since you only need to change proxy on desiredCapabilities object, there is a little hack:
// global hooks file:
module.exports = {
beforeEach: function(client, done) {
client.options.desiredCapabilities.proxy = {
"proxyType": "manual",
"httpProxy": "127.0.0.1:" + someport,
"sslProxy": "127.0.0.1:" + someport
};
done(client);
}
};
Changing desiredCapabilities object won't work, since reference to original object is already stored somewhere under the hood of Nightwatch. But nothing stops you from overriding proxy property on that object.
After checking sources and tests in Nightwatch I believe this is the only solution for your case.