Forking tests.

Each test file is run in a forked process to avoid shared state. Once a failure is found, you get a report detailing what failed and how to locate the error and the rest of the file is skipped.

You can use the scope command around tests: it guarantees that no instance variables are shared between tests.

There are two commands very similar in nature, but with a subtle difference that makes them easy to combine in order to satisfy different needs: prepare and setup.

The prepare blocks are executed before each test. If you call prepare many times, each passed block is appended to an array. When the test is run, all those prepare blocks are executed in order. The result of the block is discarded, so it is only useful for preparing the environment (flushing the database, removing a directory, etc.).

The setup block is executed before each test and the result is passed as a parameter to the test block. Unlike prepare, each definition of setup overrides the previous one. Even if you can declare instance variables and share them between tests, the recommended usage is to pass the result of the block as a parameter to the test blocks.

The test method executes the passed block after running prepare and setup. This is where assertions must be declared.

Three assertions are available: assert, that accepts a value and raises if it's false or nil; assert_equal, that raises if its arguments are not equal; and assert_raise, that executes a passed block and compares the raised exception to the expected one. In all cases, if the expectation is no met, an AssertionFailed exception is raised.

You can customize the output of assert by providing a second argument with a string you want to get as an error report if the assertion is not fulfilled. This can also be used as a simple building block to build custom assertions.

In your terminal:

$ cutest test/*.rb

In your tests:

setup do
  {:a => 23, :b => 43}
end

test "should receive the result of the setup block as a parameter" do |params|
  assert params == {:a => 23, :b => 43}
end

test "should evaluate the setup block before each test" do |params|
  params[:a] = nil
end

test "should preserve the original values from the setup" do |params|
  assert 23 == params[:a]
end

An example working with a prepare block:

prepare do
  Ohm.flush
end

setup do
  Ohm.redis.get("foo")
end

test do |foo|
  assert foo.nil?
end

And working with scopes:

setup do
  @foo = true
end

@bar = true

scope do
  test "should not share instance variables" do |foo|
    assert !defined?(@foo)
    assert !defined?(@bar)
    assert foo == true
  end
end

The tests in these two examples will pass.

Unlike other testing frameworks, Cutest does not compile all the tests before running them.

A simple example for adding a custom empty assertion:

def assert_empty(string)
  assert(string.empty?, "not empty")
end

test "failed custom assertion" do
  assert_empty "foo"
end

If you get an error when running the tests, this is what you will see:

Exception: assert_equal 24, params[:a] # 24 != 23
test/setup.rb +14

Using Rake:

task :test do
  exec "cutest test/*.rb"
end

task :default => :test

Using Make:

.PHONY: test

test:
  cutest test/*.rb

The tool cutest accepts a list of files and sends them to Cutest.run. If you need to require a file or library before running the tests, as is the case with test helpers, use the -r flag:

$ cutest -r ./test/helper.rb ./test/*_test.rb

If you want to check which version you are running, try the -v flag.

$ gem install cutest

Copyright (c) 2010 Damian Janowski and Michel Martens

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