Create assert_equal to make it easy to write tests

!macOS-11.1!ruby-2.7.2p137

Preface (Introduction)

In Test Driven Development (TDD), it is basic to repeat simple tests over and over again.

In this article, I'll create a function assert \ _equal that checks if an expression or value is the same as expected, and use it to create simple test code.

Assert

Equal

First, make sure that the values ​​of expected and result are equal.

assert_equal.rb

def assert_equal(expected, result)
  return expected == result
end

p assert_equal(1, 1)

> ruby assert_equal.rb
-> true

Then use the colorize library to color the output for visual clarity.

assert_equal.rb

require 'colorize'

def assert_equal(expected, result)
  if expected == result
    puts 'true'.green
  else
    puts 'false'.red
  end
end

assert_equal(1, 1)
assert_equal(1, 2)

The result should be green true for the first and red false for the second.

Make a few improvements.

--Output the expected and result values ​​of the arguments --Changed the processing of assert \ _equal to the following - true: print "succeeded in assert_equal.\n".green - false: print "failed in assert_equal.\n".red

assert_equal.rb

require 'colorize'

def puts_vals(expected, result)
  puts "expected :: #{expected}"
  puts "result   :: #{result}"
end
def assert_equal(expected, result)
  puts_vals(expected, result)
  print  case expected == result
     when true  ; "succeeded in #{__method__}.\n".green
     when false ; "failed in #{__method__}.\n".red
     end
end

assert_equal(1, 1)
assert_equal(1, 2)

The output is

> ruby assert_equal.rb

expected :: 1
result   :: 1
succeeded in assert_equal.
expected :: 1
result   :: 2
failed in assert_equal.

(The color has not changed on Qiita.)

Not Equal

Now create an assert \ _not \ _equal function that returns false if expected and result are equal, and true if they are different.

assert_equal.rb

require 'colorize'

def puts_vals(expected, result)
  puts "expected :: #{expected}"
  puts "result   :: #{result}"
end
def assert_not_equal(expected, result)
  puts_vals(expected, result)
  print expected != result ?
  "succeeded in #{__method__}.\n".green :
    "failed in #{__method__}.\n".red
end
def assert_equal(expected, result)
  puts_vals(expected, result)
  print  case expected == result
     when true  ; "succeeded in #{__method__}.\n".green
     when false ; "failed in #{__method__}.\n".red
     end
end

assert_equal(1, 1)
assert_equal(1, 2)
assert_not_equal(1, 2)
assert_not_equal(1, 1)

The output is

> ruby assert_equal.rb

expected :: 1
result   :: 1
succeeded in assert_equal.
expected :: 1
result   :: 2
failed in assert_equal.
expected :: 1
result   :: 2
succeeded in assert_not_equal.
expected :: 1
result   :: 1
failed in assert_not_equal.

Since this assert \ _equal and assert \ _not \ _equal are convenient, I would like to use them for other code as well. However, as it is, the tests in the code will also be executed, so

assert_equal.rb

if $PROGRAM_NAME == __FILE__
  assert_equal(1, 1)
  assert_equal(1, 2)
  assert_not_equal(1, 2)
  assert_not_equal(1, 1)
end

Change the test part like this. By writing like this, if the file name (FILE) where the code is written matches the file name ($ PROGRAM \ _FILE) where PROGRAM is running, the contents can be executed.

Reference material

Chart type ruby-IV (assert \ _equal)