Trouble mocking `Resolv::DNS.open` - ruby-on-rails

I'm trying to mock the code below using MiniTest/Mocks. But I keep getting this error when running my test.
Minitest::Assertion: unexpected invocation: #<Mock:0x7fa76b53d5d0>.size()
unsatisfied expectations:
- expected exactly once, not yet invoked: #<Mock:0x7fa76b53d5d0>.getresources("_F5DC2A7B3840CF8DD20E021B6C4E5FE0.corwin.co", Resolv::DNS::Resource::IN::CNAME)
satisfied expectations:
- expected exactly once, invoked once: Resolv::DNS.open(any_parameters)
code being tested
txt = Resolv::DNS.open do |dns|
records = dns.getresources(options[:cname_origin], Resolv::DNS::Resource::IN::CNAME)
end
binding.pry
return (txt.size > 0) ? (options[:cname_destination].downcase == txt.last.name.to_s.downcase) : false
my test
::Resolv::DNS.expects(:open).returns(dns = mock)
dns.expects(:getresources)
.with(subject.cname_origin(true), Resolv::DNS::Resource::IN::CNAME)
.returns([Resolv::DNS::Resource::IN::CNAME.new(subject.cname_destination)])
.once

Right now you are testing that Resolv::DNS receives open returns your mock but
since you seem to be trying to test that the dns mock is receiving messages you need to stub the method and provide it with the object to be yielded
Try this instead:
dns = mock
dns.expects(:getresources)
.with(subject.cname_origin(true), Resolv::DNS::Resource::IN::CNAME)
.once
::Resolv::DNS.stub :open, [Resolv::DNS::Resource::IN::CNAME.new(subject.cname_destination)], dns do
# whatever code actually calls the "code being tested"
end
dns.verify
The second argument to stub is the stubbed return value and third argument to stub is what will be yielded to the block in place of the original yielded.
In RSpec the syntax is a bit simpler (and more semantic) such that:
dns = double
allow(::Resolv::DNS).to receive(:open).and_yield(dns)
expect(:dns).to receive(:getresources).once
.with(subject.cname_origin(true), Resolv::DNS::Resource::IN::CNAME)
.and_return([Resolv::DNS::Resource::IN::CNAME.new(subject.cname_destination)])
# whatever code actually calls the "code being tested"

You can write more readable integration tests with DnsMock instead of stubbing/mocking parts of your code: https://github.com/mocktools/ruby-dns-mock

Related

Project Reactor test never completes

I have created a simple Kafka consumer that returns a Flux of objects (the received messages) and I'm trying to test it using the StepVerifier.
In my test, I do something like that:
Flux<Pojo> flux = consumer.start();
StepVerifier.create(flux)
.expectNextMatches(p -> p.getList().size() == 3)
.verifyComplete();
The assertion works ok (if I change the value from 3 to something else, the test fails). But, if the assertion passes, than the test never exit.
I have also tried to use the verify method like so:
StepVerifier.create(flux)
.expectNextMatches(f -> f.getEntitlements().size() == 3)
.expectComplete()
.verify(Duration.ofSeconds(3));
In this case, I get this error:
java.lang.AssertionError: VerifySubscriber timed out on false
Any idea what I'm doing wrong?
The Kafka Flux is probably infinite, so it never emits the onComplete signal, which the test waits for. You can call .thenCancel().verify() if you're only interested in testing that first value.

How to unit test a method for timeout exception in ruby

I want to test a method which makes a call to a service, if the call to that service times out I am displaying a negative feedback to user. How to unittest the timeout use case ??
My method looks like:
def method
x = callservice()
if x[:value]
display_positve_feedback("positive")
else
display_negative_feedback("negative")
end
rescue Timeout::Error => e
display_negative_feedback("Timeout, please wait for 5 mins and check again")
end
end
I have mocked callservice but how to I make that service Timeout to check the timeout use case???
You don't use a return code. If you add it, you could test for the method result.
Example:
def method
begin
x = callservice()
if x[:value]
display_positve_feedback("positive")
return true
else
display_negative_feedback("negative")
return false
end
rescue Timeout::Error => e
display_negative_feedback("Timeout, please wait for 5 mins and check again")
return nil
end
raise "This should never happen"
end
Now you can test on true, falseor nil.
Suppressing exceptions is usually not a good practice that I would recommend to anyone.
When you catch (rescue) the timeout exception, re-raise it (or your own application-specific one) in the rescue code and have the caller (your test) check that an exception is thrown for the timeout.
You could use assert_raise or expect raise_error, for example, depending on what testing framework you use.
Using an exception, the calling code only needs to know about a potential exception rather than having to check for specific return values, which makes the code simpler and more clear.
Stub the callservice method to raise a Timeout::Error. How you'll do that depends on what testing framework you're using. For example, in RSpec it might look something like this:
my_obj.stub(:callservice) { raise Timeout::Error }
expect(my_obj).to receive(:display_negative_feedback)
.with("Timeout, please wait for 5 mins and check again")
my_obj.method

How do I get $resource to resolve its promise in test environment

I have a controller that needs to run several asynchronous methods that interact with the data on the client and make no calls to the server. I have one method working fine in the browser, but I want to drive the methods with tests and I can't get it to work in the test environment (Karma and Mocha). The reason is that the empty array that $resource.query() returns never gets populated in the test environment because the promise doesn't get resolved. Here is my beforeEach in the test suite.
beforeEach(inject(function($rootScope, $controller, scheduleService){
scope = $rootScope.$new();
sc = $controller('scheduleCtrl', {
$scope: scope, service: scheduleService
});
scope.$apply();
}));
scheduleCtrl has a property schedule that is assigned to the result of Resource.query() in it's constructor. I can see the three returned objects loaded into the MockHttpExpectation.
But when I go to run the test sc.schedule is an still an empty array, so the test fails. How do I get the Resource.query() to resolve in the test?
Resource.query() works with promisses, which is a assync process.
It happens that your test execute before the assynchronous request have completed and before array gets populated.
You could use $httpBackend so you can call expect after $httpBackend.flush().
Or you could retrieve the $promisse returned from Resource.query().$promisse on your test and do the expectation inside its implementation.
Ex:
$scope.promisse = Resource.query().$promisse;
sc.promisse(function(values) {
expect(values.length).not.toBe(0);
});

Avoid recreating the subject in RSpec

Say I have the following test
describe "bob" do
subject {
response = get "/expensive_lookup"
JSON.parse(response.body)
}
its(["transaction_id"]) { should == 1 }
its(["order_id"]) { should == 33 }
end
Then for each its() {} the subject will be reevaluated, which in my case it is a very slow lookup.
I could bundle all my tests together in one like
describe "bob" do
subject(res) {
response = get "/expensive_lookup"
JSON.parse(response.body)
}
it "returns the right stuff" do
res["transaction_id"]).should == 1
res["order_id"].should == 33
end
end
But this makes it less obvious which line of the test has failed if there is a failure.
Is there a way I can stop the subject from being reevaluated for each it block?
You can put that in to a before(:all) block. I don't know if that syntax has changed in a new rspec version, but regardless, your test would become this:
before(:all) do
response = get "/expensive_lookup"
#res = JSON.parse(response.body)
end
it "returns the right transaction ID" do
#res["transaction_id"].should == 1
end
# etc
The pro is that the code in the before-all block gets run just once for your spec. The con is that, as you can see, you can't take advantage of the subject; you need to write each more explicitly. Another gotcha is that any data saved to the test database is not part of the transaction and will not be rolled back.
There are two possible source of issues
Network request is slow/prone to fail
You should really mock all you network requests, slow or not.
The gem VCR is excellent. It makes it trivial to run your request once and persist the result for subsequent testing.
Building the immutable subject is slow
If you have multiple it blocks, the subject will be rebuild every time. Assuming you don't modify the subject, you can build it once.
You can use before(:all):
before(:all) { #cache = very_long_computation.freeze }
subject { #cache }
Note: that I call freeze to avoid modifying it by mistake, but of course that's not a deep freeze so you still need to mind what you are doing. If you are mutating your subject, your tests are no longer independent and shouldn't share the subject.

Ruby/Rails: eval doesn't seems to work

Am trying to evaluating the below code using rspec.
Given :
# book = ...
Rails.logger.info book.inspect
The above code prints the value of return type is boolean i.e {:foo=>false}
eval(book[:foo]).should be_false
but that doesn't seem to work. While trying to run rspec, it throws the following exception:
Failure/Error: eval(book[:foo]).should be_false
TypeError:
can't convert false into String
So, how can i evaluate a boolean to a method, such as my final result would be the equivalent ?
eval executes passed argument interpreting it as Ruby code. What Ruby code do you think is contained in false object?
eval(false) # cannot execute false object
eval("false") # executes a string and returns false object
see the difference?
i don't know what exactly are you testing but you could simply try
book[:foo].should be_false

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