Difference between :each and :all

I’m having a hard time grasping the difference between :each and :all.

If I have a bunch of stuff inside a “before :each” block. Everytime I
try to run an example that block of code will be run before the example.

Now if I had the same code inside a “before :all” block. Everytime an
example is run, that block will still be run. Yielding the same results.
At least in my mind.

The RSpec book says something like “before :each” defines a state for
each example. “before :all” defines a state for all the examples. But
what’s the difference?

Here’s an illustrative example that should clear things up:

require ‘spec_helper’

describe “behavior of before-each and before-all” do
before(:all) { puts “-- running :all” }
before(:each) { puts “-- running :each” }

describe “addition” do
it “should add two and two” do
(2 + 2).should == 4
end

it "should add three and three" do
  (3 + 3).should == 6
end

it "should add four and four" do
  (4 + 4).should == 8
end

end

describe “multiplication” do
it “should raise two to two” do
(2 ** 2).should == 4
end

it "should raise three to three" do
  (3 ** 3).should == 27
end

it "should raise four to four" do
  (4 ** 4).should == 256
end

end
end

And here’s the result:

behavior of before-each and before-all
– running :all
addition
– running :each
should add two and two
– running :each
should add three and three
– running :each
should add four and four
multiplication
– running :each
should raise two to two
– running :each
should raise three to three
– running :each
should raise four to four

Finished in 0.0034 seconds
6 examples, 0 failures

Notice how :each runs before each spec, but :all runs once, before
_any_spec.

John F.
Principal Consultant, BitsBuilder
LI: http://www.linkedin.com/in/fjsquared
SO: http://stackoverflow.com/users/75170/

That’s not quite right. :each runs before each spec, while :all runs
once, before any spec.

John F.
Principal Consultant, BitsBuilder
LI: http://www.linkedin.com/in/fjsquared
SO: http://stackoverflow.com/users/75170/

On Jan 27, 2011, at 5:11 PM, John F. wrote:

That’s not quite right. :each runs before each spec, while :all runs
once, before any spec.

Perhaps :any is a better name? We could add it as an alternative for the
same as :all. WDYT?

Perhaps :any is a better name? We could add it as an alternative for the same as
:all. WDYT?

I think that’s an interesting idea, David. I whipped up a quick pull
request, which you can see here:

https://github.com/rspec/rspec-core/pull/293

~ jf

John F.
Principal Consultant, BitsBuilder
LI: http://www.linkedin.com/in/fjsquared
SO: http://stackoverflow.com/users/75170/

That does clear it. Thank you =]

On Thu, Jan 27, 2011 at 6:16 PM, David C. [email protected]
wrote:

On Jan 27, 2011, at 5:11 PM, John F. wrote:

That’s not quite right. :each runs before each spec, while :all runs
once, before any spec.

Perhaps :any is a better name? We could add it as an alternative for the same as
:all. WDYT?

Speaking for myself, I never was confused between before(:each) and
before(:all). The first always meant before each OF the examples, and
the latter before all the examples.

As a devil’s advocate, while before(:any) might evoke the current
meaning of before(:all) for some people, after(:any) to me evokes the
curent meaning of after(:each) more than it does after(:all), i.e.
after any OF the examples rather than after all the examples, because
I’d never say after any the examples.

But that might just be me.


Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Github: http://github.com/rubyredrick
Twitter: @RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale

My understanding is that the before :each block runs before every
example.
While before :all blocks run once for the entire example group.

Any side effects in the examples will be persist for objects if you use
a
before :all block. But if you were to use before :each, you guarantee
the
state before every example is run.

Stupid code example.

describe “stuff”
before :all do
puts “done one time”
end

before :each do
puts “done once for every example”
end

describe “one thing stuff does” do
end

describe “second thing stuff does” do
end
end

You’d see something like this in the output:
done one time
done once for every example
done once for every example

Again, this is just my understanding. Could be wrong.
Jon Homan

Not to shoot my own patch in the foot, but my personal opinion is to
have only one way to do it. I think whatever ambiguity there may be in
before(:all) isn’t adequately compensated by the additional confusion
of having before(:any), which sounds like it would do something subtly
different.

John F.
Principal Consultant, BitsBuilder
LI: http://www.linkedin.com/in/johnxf
SO: http://stackoverflow.com/users/75170/

El 28/01/2011, a las 03:53, Rick DeNatale escribi:

before(:all).
Same. When you look at them side by side like that, it is pretty clear
what “before each” and “before all” must refer to. Adding a third term
to the mix would actually increase the chance of confusion, IMO.

Cheers,
Wincent

On Thu, Jan 27, 2011 at 8:53 PM, Rick DeNatale [email protected]
wrote:

before(:all). The first always meant before each OF the examples, and
the latter before all the examples.

As a devil’s advocate, while before(:any) might evoke the current
meaning of before(:all) for some people, after(:any) to me evokes the
curent meaning of after(:each) more than it does after(:all), i.e.
after any OF the examples rather than after all the examples, because
I’d never say after any the examples.

But that might just be me.

You’re absolutely right that it would be confusing for after, and
given that, I think we should probably not add it.

On Jan 27, 2011, at 6:53 PM, Rick DeNatale [email protected]
wrote:

before(:all). The first always meant before each OF the examples, and

http://rubyforge.org/mailman/listinfo/rspec-users
I feel like a third option will cause more confusion, especially if it’s
just an alias of an existing option!

Pat

Btw. there is also before(:suite), and working from there wouldn’t it
make sense to have

  1. before(:suite)
  2. before(:group)
  3. before(:example)

which would reflect the hierarchy of RSpec run (i.e. suite > group >
example).

Anyway likely it’s too late to introduce something like this, just my 2
cents, because I’m from
these folks which were always confused about :each/:all and what is the
default, etc. when
I just started speccing.

On Jan 31, 2011, at 3:38 AM, Evgeniy D. wrote:

Btw. there is also before(:suite), and working from there wouldn’t it make sense
to have

  1. before(:suite)
  2. before(:group)
  3. before(:example)

which would reflect the hierarchy of RSpec run (i.e. suite > group > example).

That or :once and :always

SR

On Jan 31, 2011, at 3:38 AM, Evgeniy D. wrote:

Btw. there is also before(:suite), and working from there wouldn’t it make sense
to have

  1. before(:suite)
  2. before(:group)
  3. before(:example)

which would reflect the hierarchy of RSpec run (i.e. suite > group > example).

I really, really like this. It maps well to the afters as well, and
therefore does not add to confusion the way :any would.

Anyway likely it’s too late to introduce something like this, just my 2 cents,
because I’m from
these folks which were always confused about :each/:all and what is the default,
etc. when
I just started speccing.

I don’t think it’s too late for this. I’m not convinced to do it yet,
but I think this is a solid, clear direction.

More opinions on this?

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