What is the difference between let and let RSpec?
(:let) is lazily evaluated and will never be instantiated if you don’t call it, while (:let!) is forcefully evaluated before each method call.
What is let in RSpec?
What does let do? let generates a method whose return value is memoized after the first call. This is known as lazy loading because the value is not loaded into memory until the method is called. Here is an example of how let is used within an RSpec test.
What is assigns RSpec?
assigns relates to the instance variables created within a controller action (and assigned to the view).
How do I run a specific test in RSpec?
Running tests by their file or directory names is the most familiar way to run tests with RSpec. RSpec can take a file name or directory name and run the file or the contents of the directory. So you can do: rspec spec/jobs to run the tests found in the jobs directory.
Where can a let Block be defined in RSpec?
The let method should be called inside an example group. The first argument is the name of a variable to define. The let method is passed a block that computes the value of the variable, and the block will be called if the value of the variable is ever needed. In other words, let variables are lazily evaluated.
What is double in RSpec?
A Double is an object which can “stand in” for another object. You’re probably wondering what that means exactly and why you’d need one. This is a simple class, it has one method list_student_names, which returns a comma delimited string of student names.
How do I set an instance variable in RSpec?
If you want to set a controller or view’s instance variables in your RSpec test, then call assign either in a before block or at the start of an example group. The first argument is the name of the instance variable while the second is the value you want to assign to it.
What is Instance_variable_get in Ruby?
instance_variable_get is a method defined on Object that works much the same way as const_get . It allows you to retrieve the value of an instance variable defined on your class or module. Example Code: class Monk def initialize @zen = 42 end end p Monk.new.instance_variable_get(“@zen”)
How do I run a single test case in Rspec?
- You can run your tests like bundle exec rspec ./spec/controllers/groups_controller_spec.rb:6, it runs this specific test only. More info here: kolosek.com/rails-rspec-setup. – Nesha Zoric. Feb 21, 2018 at 11:22.
- bundle exec rspec spec –help wil give you the answer: – Thomas Decaux. May 9, 2018 at 19:17.
How do I debug in Rspec?
4 tips on debugging rspec unit tests
- 1) Format Your RSpec Test Results. If this is your first time running rspec, the first thing you’ll probably do is run rake spec.
- 2) Use pry To Set Breakpoints. The next thing you should do is download the wildly popular gem pry here.
- 3) Print Out Everything!
- 4) Isolate Your Tests.
Where can a let Block be defined?
What is mocking in Ruby?
Mocking is a technique in test-driven development (TDD) that involves using fake dependent objects or methods in order to write a test.
How do I mock an instance variable in RSpec?
You can’t mock an instance variable. You can only mock methods. One option is to define a method inside OneClass that wraps the another_member , and mock that method. However, you don’t have to, there is a better way to write and test your code.
What is {} in Ruby?
As well as hashes, the general style is that curly braces {} are often used for blocks that can fit all onto one line, instead of using do / end across several lines. Square brackets [] are used as class methods in lots of Ruby classes, including String, BigNum, Dir and confusingly enough, Hash.
What is ||= in Ruby?
a ||= b is a conditional assignment operator. It means: if a is undefined or falsey, then evaluate b and set a to the result. Otherwise (if a is defined and evaluates to truthy), then b is not evaluated, and no assignment takes place.
Is RSpec TDD or BDD?
RSpec is a testing tool for Ruby, created for behavior-driven development (BDD). It is the most frequently used testing library for Ruby in production applications. Even though it has a very rich and powerful DSL (domain-specific language), at its core it is a simple tool which you can start using rather quickly.
Is readapt included in your Gemfile?
Note that readapt must be included in your Gemfile for useBundler to work.
How do I debug a Ruby script?
To help deal with bugs, the standard distribution of Ruby includes a debugger. In order to start the Ruby debugger, load the debug library using the command-line option -r debug. The debugger stops before the first line of executable code and asks for the input of user commands.
Why is let better than VAR?
let allows you to declare variables that are limited to the scope of a block statement, or expression on which it is used, unlike the var keyword, which declares a variable globally, or locally to an entire function regardless of block scope.
Can I Redeclare let and const variables?
Constants are block-scoped, much like variables declared using the let keyword. The value of a constant can’t be changed through reassignment (i.e. by using the assignment operator), and it can’t be redeclared (i.e. through a variable declaration).
What is stubbing in RSpec?
In RSpec, a stub is often called a Method Stub, it’s a special type of method that “stands in” for an existing method, or for a method that doesn’t even exist yet. Here is the code from the section on RSpec Doubles − class ClassRoom def initialize(students) @students = students End def list_student_names @students.
What is a stub vs mock?
Stub: a dummy piece of code that lets the test run, but you don’t care what happens to it. Substitutes for real working code. Mock: a dummy piece of code that you verify is called correctly as part of the test. Substitutes for real working code.
What is instance double?
An instance_double is the most common type of verifying double. It takes a class name or. object as its first argument, then verifies that any methods being stubbed would be present. on an instance of that class.
What is :: in Ruby?
The :: is a unary operator that allows: constants, instance methods and class methods defined within a class or module, to be accessed from anywhere outside the class or module. Remember in Ruby, classes and methods may be considered constants too.
Do vs {} Ruby?
do-end is usually used for blocks that span through multiple lines while {} is used for single line blocks. Blocks can have arguments which should be defined between two pipe | characters.