rspec shared examples vs shared context

Question

What is the real difference between shared_examples and shared_context ?

My observations :

1. I can test same things using both (i.e. with shared_examples or shared_context)

2. But some of my other tests fails if I use later one.

Observation #1 :

I compared shared_examples and shared_context per documentation on https://www.relishapp.com/

Syntactical differences are :

• shared_context to define a block that will be evaluated in the context of example groups by implicitly matching metadata

Example :

shared_context "shared stuff", :a => :b do   ... end 

• The way these are included or called from a test file

shared_examples

include_examples "name"      # include the examples in the current context it_behaves_like "name"       # include the examples in a nested context it_should_behave_like "name" # include the examples in a nested context 

shared_context

include_context "shared stuff" 

Observation #2

I have a test case

shared_context 'limit_articles' do |factory_name|   before do     @account = create(:account)   end    it 'should restrict 3rd article' do     create_list(factory_name, 3, account: @account)      article4 = build(factory_name, account: @account)     article4.should be_invalid   end    it 'should allow 1st article' do     ...   end    it 'should allow 2nd article' do     ...   end end 

And include the context in a spec file which already has one shared_context included, then the existing one fails. But I change the order then all my test passes

Fails

include_context 'existing_shared_context'  include_context 'limit_articles' 

Also if I replace the shared_context with shared_examples and accordingly include it in test case.

Passes

include_context 'existing_shared_context'  it_behaves_like 'limit_articles' 

Answer 1

shared_examples are tests written in a way that you can run them in multiple settings; extracting common behavior between objects.

it_behaves_like "a correct object remover" do     ... end 

shared_contexts is any setup code that you can use to prepare a test case . This allows you to include test helper methods or prepare for the tests to run.

include_context "has many users to begin with" 

Answer 2

shared_examples contain a collection of examples which you can include in other describe blocks.

A shared_context contains a collection of shared code, which you can include in your test file. Think of this like a ruby module.

You use a shared_context in your test code by including it with the include_context method.

On the other hand, you state that a certain thing behaves_like a shared example group.

It's a matter of readability I guess.

UPDATE:

If you look at the source code you'll see that they're exactly the same thing. Check out line 98 in this file:

https://github.com/rspec/rspec-core/blob/master/lib/rspec/core/shared_example_group.rb#L98

alias_method :shared_context,      :shared_examples 

You'll also see that shared_examples_for is another alias for the same method.