Expectacular¶ ↑

A small DSL to write meaningful assertions on your test/unit tests.

Usage¶ ↑

require "expectacular"

class TestFoo < Test::Unit::TestCase
  include Expectacular::TestCaseMethods

  def test_obviousness
    expect(1).to == 1

expect(5).to.be > 3 expect(nil).to.be_nil expect(5).not_to == 4

  end
end

Expectations¶ ↑

Including Expectacular::TestCaseMethods will add your test cases a single method: expect, which takes any object as an argument and returns an Expectacular::Expectation in return. You can do assertions on expectations, by calling the methods Expectation#to and Expectation#not_to.

expect(1).to == 1
expect(3).not_to == 0

to and not_to return an Assertion. In its context you can call several methods to test the behavior of your objects.

Assertions¶ ↑

Expectacular comes with some assertions bundled:

• Predicates (be_foo to check that foo? returns true)

• be_a(Foo) to test ancestorship (is_a?(Foo))

Whenever you call a method that is not one of the above, the method (and any arguments) get forwared to the object in which you set the expectation, and the result is treated as the assertion (if it returns true the test is considered to pass, if it returns false it considers the assertion to fail – unless you are using not_to, in which case it’s the other way around.)

For example, Expectacular doesn’t define any operator assertions, those are forwarded to the object you’re setting expectations on. So the following:

expect(foo).to =~ /bar/
expect(foo).not_to == "bars"

Just calls foo =~ /bar/ and !(foo == "bars") and makes an assertion for each of those.

Writing your own assertions it’s stupidly easy¶ ↑

module MyAwesomeAssertion
  THRESHOLD = 10_000

  def be_very_awesome
    assert(object.awesomeness >= THRESHOLD,

“Expected #{object} to be very awesome”)

  end
end

Expectacular::Assertion.add MyAwesomeAssertion

expect(foo).to.be_very_awesome

Assertions have access to the following two methods:

object

which returns the object on which you’re setting the expectation.

assert

which takes a boolean value and a failure message.

You can also pass a block to Assertion.add with the method definitions, so the above example could also be written as:

Expectacular::Assertion.add do
  THRESHOLD = 10_000

  def be_very_awesome
    assert(object.awesomeness >= THRESHOLD,
           "Expected #{object} to be very awesome")
  end
end

expect(foo).to.be_very_awesome

Why?¶ ↑

Mostly, as an experiment, also, I usually don’t like libraries that mess around with core classes, so this one doesn’t :)

Credits¶ ↑

Thanks to Daniel Cadenas (github) for design and syntax ideas.

Author

Nicolás Sanguinetti (github)

License

MIT. See attached LICENSE file for details.