Jasmine is a behavior-driven development framework for testing JavaScript code. It uses a syntax that is very similar to RSpec, with describe blocks to group specs and expectations, and hooks like beforeEach, afterEach, beforeAll and afterAll. Both frameworks support expectations, stubbing, mocking, and error handling in a comparable way. The document provides examples of common testing patterns in Jasmine and compares them side-by-side to their RSpec equivalents to illustrate how Rubyists can easily transition to testing JavaScript with Jasmine.

1. Javascript Specs
with Jasmine
A Primer for Rubyists

2. Why Test Javascript?

3. Seems like a
lot of work
just for some lousy
regression tests...

4. Enforces Good Design
•Object Oriented-er
• Modular and Namespaced
• Flexible, Updatable, Reusable

5. Focus and Process
• Driven by Business
Requirements
• Red, Green, Refactor
• Know When You’re Done

6. “Free” Documentation
•Legible Output
• Expresses Object Behavior
• Get Devs Up to Speed

7. Oh yeah...
plus you get a
regression test suite

8. Why Use Jasmine?

9. Friends with RSpec
•Very Similar Syntax
• “BDD” Approach
• Continuous Integration
• Borrows Directory Structure
• Generative Fixture Support

10. Pals with Ruby / Rails
$ gem install jasmine
$ script/generate jasmine
$ rake jasmine

11. Jasmine / RSpec
Comparisons
Let’s get cookin’...

12. Spec Suites
describe Cook do
describe “baking a pie” do
# ...
end
end
RSpec
describe(“Cook”, function() {
describe(“baking pie”, function() {
// ...
});
});
Jasmine

13. Before / After
before(:each) do
@pie = Pie.new
end
after(:each) { @pie.cleanup }
RSpec
Jasmine
var pie;
beforeEach(function(){
pie = new Pie();
});
afterEach(function() {pie.cleanup()});

14. Before All / After All
before(:all) { setup_code }
after(:all) { cleanup_code }
describe “something” do
# ... tests here
end
RSpec
setupCode();
describe(“something”, function() {
// ... tests here
});
cleanupCode();
Jasmine

15. Examples / Expectations
it “should be tasty” do
pie = Pie.new
pie.should be_tasty
end
RSpec
it(“should be tasty”, function() {
var pie = new Pie();
expect(pie).toBeTasty();
});
Jasmine

16. Negative Expectations
it “should not be burned” do
pie = Pie.new
pie.bake!
pie.should_not be_burned
end
RSpec
it(“should not be burned”, function(){
var pie = new Pie();
pie.bake();
expect(pie).not.toBeBurned();
});
Jasmine

17. Custom Matchers
Spec::Matchers.define :be_burned do
match do |actual|
actual.color == “black”
end
end
RSpec
beforeEach(function() {
this.addMatchers({
toBeBurned: function() {
return this.actual.color == ‘black’;
}
});
});
Jasmine

18. Stubbing Values
it “should cook until 160 degrees” do
pie = Pie.new
pie.stub!(:temperature).and_return(160)
pie.done_baking?.should be_true
end
RSpec
it(“should cook until 160 degrees”, function() {
var pie = new Pie();
spyOn(pie, ‘temperature’).andReturn(160);
expect(pie.doneBaking()).toBeTruthy();
});
Jasmine

19. Message Expectations
it “should bake a pie for dinner” do
cook = Cook.new
cook.should_receive(:bake_a_pie!)
cook.make_dinner!
end
RSpec
it(“should bake a pie”, function() {
var cook = new Cook();
spyOn(cook, ‘bakePie’);
cook.makeDinner();
expect(cook.bakePie).toHaveBeenCalled();
});
Jasmine

20. Expectations w/ Args
it “should bake a TASTY pie” do
cook = Cook.new
cook.should_receive(:bake_a_pie!).with(‘TASTY’)
cook.make_dinner!
end
RSpec
it(“should bake a TASTY pie”, function() {
var cook = new Cook();
spyOn(cook, ‘bakePie’);
cook.makeDinner();
expect(cook.bakePie)
.toHaveBeenCalledWith(‘TASTY’);
});
Jasmine

21. Stub Call-Through
RSpec
it(“should bake a TASTY pie”, function() {
var cook = new Cook();
spyOn(cook, ‘bakePie’).andCallThrough();
cook.makeDinner();
expect(cook.bakePie)
.toHaveBeenCalledWith(‘TASTY’);
});
Jasmine

22. Number of Times
it “should check the pie twice” do
cook = Cook.new
cook.should_receive(:check_the_pie).twice
cook.bake_a_pie!
end
RSpec
it(“should check the pie twice”, function() {
var cook = new Cook();
spyOn(cook, ‘checkThePie’);
cook.bakePie();
expect(cook.checkThePie.callCount).toEqual(2);
});
Jasmine

23. Error Expectations
it “should refuse to bake a pie” do
cook = Cook.new(“cranky”)
lambda do
cook.bake_a_pie!
end.should raise_error(MakeYourOwnDamnPie)
end
RSpec
it(“should refuse to bake a pie”, function() {
var cook = new Cook(‘cranky’);
var msg = “Make Your Own Damn Pie!”;
expect(cook.bakePie).toThrow(msg);
});
Jasmine

24. Simulating Errors
it “should catch errs & retry with sudo” do
cook = Cook.new
cook.stub!(:bake_a_pie!).
and_raise(MakeYourOwnDamnPie)
cook.should_receive(:sudo_bake_a_pie!)
cook.make_dinner!
end
RSpec

25. Simulating Errors
it(“should retry with sudo”, function() {
var cook = new Cook();
spyOn(cook, ‘bakePie’)
.andThrow(“Make Your Own Damn Pie!”);
spyOn(cook, ‘sudoBakePie’);
expect(cook.sudoBakePie).toHaveBeenCalled();
});
Jasmine

26. Well now that I’m
HUNGRY
let’s write some code...