minitest assert custom assertion fails - ruby

I'm using custom assertions in my minitests and I want to unit test my assertions. Of course I can test the happy path but I want to assert that a test actually fails.
module Minitest
module Assertions
def assert_exists(value, msg = nil)
assert(!value.to_s.empty?, msg)
end
end
end
In my test I want to write something like
describe 'Assertions' do
it 'is empty' do
assert_raises assert_exists('')
end
end
Is there a way to do this?

Something like this? (You need to specify the exception you are expecting, and pass the call as a block):
describe 'Assertions' do
it 'is empty' do
assert_raises(Minitest::Assertion) do
assert_exists('')
end
end
end
This will include the call to assert in your assert_raises in the summary, which may not be exactly what you expect, but otherwise works.

Related

How to write an rspec for raise, rescue block

I want to write rspec to test this method
def path_exception
begin
# #path value need to mocked/stubbed if needed.
raise if Dir[File.join(#path, '**/*.rb')].empty?
rescue
puts 'Not appropriate path found'
end
end
I have written this rspec and calling only the method but its still giving success without any expectation
context '#wrong_path_exception' do
it 'raises exception when path is not valid' do
operation.path_exception
end
end
what is the correct way to write rspec for raise if condition true/false and rescue.
Although your method calls raise, that exception isn't visible to the outside because of rescue, which turns it into output to stdout.
You could set an expectation via the output matcher, e.g.:
expect { operation.path_exception }.to output('Not appropriate path found').to_stdout
Note that you don't need exceptions to generate output. You can just use control expressions like your if expression:
def path_exception
if Dir[File.join(#path, '**/*.rb')].empty?
puts 'Not appropriate path found'
end
end
But according to the method's name (path_exception) I think you actually want to raise an exception. So the actual fix might be to remove rescue:
def path_exception
if Dir[File.join(#path, '**/*.rb')].empty?
raise 'Not appropriate path found'
end
end
along with the raise_error matcher:
expect { operation.path_exception }.to raise_error('Not appropriate path found')

Testing with Rspec - The correct way

My weakest point when it comes to coding, is using TDD & BDD methods - I tend to just write code.. but it is something that I am trying to work on.
Could anyone point out the best way to go about the following problem:
Class1:
module TempMod
class MyClass
def initalize(config)
#config = config
end
def process(xml)
if react_upon? xml.something
puts 'yeah'
else
puts 'nah'
end
end
def react_upon?(xml_code)
#code here
end
end
end
So lets say I wanted to test this class, or build it from a TDD point of view so I write my tests:
describe TempMod::MyClass do
let(:config) {double}
let(:myclass) {TempMod::MyClass.new config}
context 'Given that the xml is something we react upon' do
it 'should check that it is valid' do
myclass.process '<some><xml>here</xml></some>'
end
it 'should output yea'
end
end
How do I test that it is calling the react_upon? method. Do I even want to see it is calling it?
Is the proper way to test it, to test all the functions like the react_upon? itself independently of the other functions?
This is properly the main thing that is most confusing me with this sort of testing. Am I testing the whole class, or just individually testing the functions, and not their interactions with the other functions in that class?
Also I realize the the react_upon? might not adhere to the Single responsibility principle and I would probably move that out to its own module/class which I could test using a stub.
If anyone can shed some light on this for me that would be awesome.
edit:
describe TempMod::MyClass do
let (:valid_planning_status_xml) {
'<StatusUpdate> <TitleId>2329</TitleId> <FromStatus>Proposed</FromStatus> <ToStatus>Confirmed</ToStatus> </StatusUpdate>'
}
let(:config) { double }
let(:status_resolver) { double }
subject(:message_processor) { TempMod::MyClass.new config, status_resolver }
context 'Given that the message XML is valid' do
it 'should check the context of the message' do
expect(message_processor.process valid_planning_status_xml).to call :check_me
end
context 'Given that the message is for a planning event update' do
it 'should call something' do
pending
end
end
context 'Given that the message is for a recording job update' do
end
context 'Given that the message is for a video title update' do
end
end
end
Your question confused me a bit is this what you are asking
module TempMod
class MyClass
def initalize(config)
#config = config
end
def process(xml)
react_upon?(xml.something) ? 'yeah' : 'nah'
end
def react_upon?(xml_code)
#code here
end
end
end
Then test like
describe TempMod::MyClass do
let(:config) {double}
let(:myclass) {TempMod::MyClass.new config}
context 'Given that the xml is something we react upon' do
it "should respond to react_upon?" do
expect(myclass).to respond_to(:react_upon?)
end
it "should react_upon? valid xml" do
expect(myclass.react_upon?(YOUR VALID REACTION GOES HERE)).to be_true
end
it "should not react_upon? invalid xml" do
expect(myclass.react_upon?(YOUR INVALID REACTION GOES HERE)).to be_false
end
it "should say 'yeah' if it is valid" do
expect(myclass.process('<some><xml>here</xml></some>')).to eq('yeah')
end
it "should say 'nah' if it is invalid" do
expect(myclass.process('<some><xml>here</some>')).to eq('nah')
end
it 'should check the context of the message' do
expect(myclass).to receive(:react_upon?).with('<some><xml>here</xml></some>')
myclass.process('<some><xml>here</xml></some>')
end
end
end
Right now your tests have no expectations so I added one that expects myclass to respiond_to the react_upon? method and another that expects myclass.process(xml) to respond with a String that equals yeah.

Minitest spec custom matcher

I have a line in my test:
page.has_reply?("my reply").must_equal true
and to make it more readable I want to use a custom matcher:
page.must_have_reply "my reply"
Based on the docs for https://github.com/zenspider/minitest-matchers I expect I need to write a matcher which looks something like this:
def have_reply(text)
subject.has_css?('.comment_body', :text => text)
end
MiniTest::Unit::TestCase.register_matcher :have_reply, :have_reply
The problem is that I can't see how to get a reference to the subject (i.e. the page object). The docs say "Note subject must be the first argument in assertion" but that doesn't really help.
There is a little example, you can create a class which should responds to set of methods matches?, failure_message_for_should, failure_message_for_should_not.
In matches? method you can get the reference to the subject.
class MyMatcher
def initialize(text)
#text = text
end
def matches? subject
subject =~ /^#{#text}.*/
end
def failure_message_for_should
"expected to start with #{#text}"
end
def failure_message_for_should_not
"expected not to start with #{#text}"
end
end
def start_with(text)
MyMatcher.new(text)
end
MiniTest::Unit::TestCase.register_matcher :start_with, :start_with
describe 'something' do
it 'must start with...' do
page = 'my reply'
page.must_start_with 'my reply'
page.must_start_with 'my '
end
end
There are many ways to get what you want here. The easiest way is to not mess with assertions, expectations, or matchers at all and just use an assert. So, assuming you already have the has_reply? method defined, you could just use this:
assert page.has_reply?("my reply")
But, that doesn't get you the must_have_reply syntax you are asking for. And I doubt you really have a has_reply? method. So, let's start.
Your asked "how to get a reference to the subject (i.e. the page object)". In this case the subject is the object that the must_have_reply method is defined on. So, you should use this instead of subject. But its not as straightforward as all that. Matchers add a level of indirection that we don't have with the usual Assertions (assert_equal, refute_equal) or Expectations (must_be_equal, wont_be_equal). If you want to write a Matcher you need to implement the Matcher API.
Fortunately for you you don't really have to implement the API. Since it seems you are already intending on relying on Cabybara's have_css matcher, we can simply use Capybara's HaveSelector class and let it implement the proper API. We just need to create our own Matchers module with a method that returns a HaveSelector object.
# Require Minitest Matchers to make this all work
require "minitest/matchers"
# Require Capybara's matchers so you can use them
require "capybara/rspec/matchers"
# Create your own matchers module
module YourApp
module Matchers
def have_reply text
# Return a properly configured HaveSelector instance
Capybara::RSpecMatchers::HaveSelector.new(:css, ".comment_body", :text => text)
end
# Register module using minitest-matcher syntax
def self.included base
instance_methods.each do |name|
base.register_matcher name, name
end
end
end
end
Then, in your minitest_helper.rb file, you can include your Matchers module so you can use it. (This code will include the matcher in all tests.)
class MiniTest::Rails::ActiveSupport::TestCase
# Include your module in the test case
include YourApp::Matchers
end
Minitest Matchers does all the hard lifting. You can now you can use your matcher as an assertion:
def test_using_an_assertion
visit root_path
assert_have_reply page, "my reply"
end
Or, you can use your matcher as an expectation:
it "is an expectation" do
visit root_path
page.must_have_reply "my reply"
end
And finally you can use it with a subject:
describe "with a subject" do
before { visit root_path }
subject { page }
it { must have_reply("my reply") }
must { have_reply "my reply" }
end
Important: For this to work, you must be using 'gem minitest-matchers', '>= 1.2.0' because register_matcher is not defined in earlier versions of that gem.

Detect Rspec test failure on after each method

I am trying to run an RSpec test, and I want to detect if the test failed in the after method. I have something like this right now:
after(:each) do
cc = ConnectController.new()
cc.update(<TEST-SERVER-CONTROLLER>, <TC-RESULT-ID>, result?)
end
As you can see, the result? function is what I need to replace, to detect if the test fails or not, and to also get information about the test that failed.
In addition to Daniel's answer, in Rspec3 the example method was deleted (see here for more info).
You will have to do something like this:
after(:each) do |example|
if example.exception
# ...
end
end
EDIT: this answer is only valid for RSpec 2. for RSpec 3 see geekazoid's answer.
The after each block runs in the context of class which exposes example and you can detect failures by checking the exception method on example thusly:
after(:each) do
if example.exception != nil
# Failure only code goes here
end
end
I was looking for how to check if success for all examples in a group in a after(:context) / after(:all) block. Here's what I came up with:
after(:all) do |example_group|
all_groups = example_group.class.descendants
failed_examples = all_groups.map(&:examples).flatten.select(&:exception)
if failed_examples.empty?
# runs only if there are no failures
do('something')
end
end

How to run arbitrary object method from string in ruby?

So I'm fairly new to ruby in general, and I'm writing some rspec test cases for an object I am creating. Lots of the test cases are fairly basic and I just want to ensure that values are being populated and returned properly. I'm wondering if there is a way for me to do this with a looping construct. Instead of having to have an assertEquals for each of the methods I want to test.
For instace:
describe item, "Testing the Item" do
it "will have a null value to start" do
item = Item.new
# Here I could do the item.name.should be_nil
# then I could do item.category.should be_nil
end
end
But I want some way to use an array to determine all of the properties to check. So I could do something like
propertyArray.each do |property|
item.#{property}.should be_nil
end
Will this or something like it work? Thanks for any help / suggestions.
object.send(:method_name) or object.send("method_name") will work.
So in your case
propertyArray.each do |property|
item.send(property).should be_nil
end
should do what you want.
If you do
propertyArray.each do |property|
item.send(property).should be_nil
end
within a single spec example and if your spec fails then it will be hard to debug which attribute is not nil or what has failed. A better way to do this is to create a separate spec example for each attribute like
describe item, "Testing the Item" do
before(:each) do
#item = Item.new
end
propertyArray.each do |property|
it "should have a null value for #{property} to start" do
#item.send(property).should be_nil
end
end
end
This will run your spec as a different spec example for each property and if it fails then you will know what has failed. This also follows the rule of one assertion per test/spec example.
A couple points about Object#send()...
You can specify parameters for the method call too...
an_object.send(:a_method, 'A param', 'Another param')
I like to use this other form __send__ because "send" is so common...
an_object.__send__(:a_method)

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