Testing classes making API calls

ruby-talk
1

I am currently working on a project which gets a lot of info from the
YouTube API and does some data mining with it.
However I would really like to have the best test coverage possible. I
thought about writing a mock up class that replaces the class making all
the YouTube API calls for tests. But I still would be able to get the
class, making the calls, covered since all my results so heavily depend
on this.

Are there any best practices for these situation?

Thank you very much for all answers!

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2

Hi Alexander,

I've run into the same problem and I did exactly what you're suggesting. You don't want to slow down your tests by making external API calls and since I'm assuming that you already know the behavior of the YouTube API, it makes sense to mimic that behavior in a mock class. Also, you will get great coverage results by doing this :slight_smile:

Joseph Gutierrez
Web Developer - Inc21
jgutierrez@inc21.com

Alexander Murmann wrote:

···

I am currently working on a project which gets a lot of info from the
YouTube API and does some data mining with it.
However I would really like to have the best test coverage possible. I
thought about writing a mock up class that replaces the class making all
the YouTube API calls for tests. But I still would be able to get the
class, making the calls, covered since all my results so heavily depend
on this.

Are there any best practices for these situation?

Thank you very much for all answers!
  
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3

I've run into the same problem and I did exactly what you're suggesting.
You don't want to slow down your tests by making external API calls and
since I'm assuming that you already know the behavior of the YouTube
API, it makes sense to mimic that behavior in a mock class. Also, you
will get great coverage results by doing this :slight_smile:

When mocking an API, I often write a test like this:

  def toast_youtuber
    yt = YouTuber.new
    puts yt.fetch('some_feed')
  end

It's a "toast" - a temporary test that will toast your test run if you
accidentally integrate it. Switch it from "toast" to "test" in your editor,
run it, and inspect the output.

Switch it back to "toast", and copy the output into a sample file. Stash
that in your test/fixtures folder, and use it when you mock the wire
connection.

  def test_youtuber_fetch
     yt = YouTuber.new
     yt.expects(:fetch).returns(File.read(RAILS_ROOT +
'/test/fixtures/youtuber.xml'))
     yt.fetch('some_feed')
     assert{ yt.feed == 'some_data' }
  end

The .expects is a Mocha mock. Note we don't mock the whole object - just the
low-level part that hits the wire. (Unit tests that hit any outgoing wires
are not just slow, they are evil.)

Whenever you need to upgrade your mock data, just turn on the toast test
again and pull another real feed.

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  Phlip