solid_assert
solid_assert is a simple implementation of an assert
utility in Ruby. It let you write tests for your assumptions while coding.
Assertions are meant to test conditions about the integrity of your code. You should use them for testing assumptions like the following:
- If the flow reaches here, then this variable has to have this value.
- This line of code should never be executed.
- At this point, this list should contain one entry for each key in this hash.
Notice that assertions shouldn't be used for handling error situations. Use Ruby built-in exception handling for that.
Assertions are typically used in development mode. You might want to disable them in production for performance reasons.
Installation
In your Gemfile
gem "solid_assert"
Usage
You can enable assertions with
SolidAssert.enable_assertions
Assertions are disabled by default.
Use assert
for testing conditions. You can optionally provide a message
assert some_string != "some value"
assert clients.empty?, "Isn't the clients list empty?"
Use invariant
for testing blocks of code. This comes handy when testing your assumptions requires several lines of code. You can provide an optional message if you want
invariant do
one_variable = calculate_some_value
other_variable = calculate_some_other_value
one_variable > other_variable
end
invariant "Lists with different sizes?" do
one_variable = calculate_some_value
other_variable = calculate_some_other_value
one_variable > other_variable
end
Rails
Create a file named solid_assert.rb
in the config/initializers
dir with the following content:
SolidAssert.enable_assertions if !Rails.env.production?
This way assertions will be disabled in production and enabled in the rest of environments
References
- Programming with assertions. A great article on assertions. It is about the Java language, but the concepts apply to any programming language.
- There are good references to assertive programming in some classic books like The Pragmatic Programmer From Journeyman to Master, Code Complete and Writing solid code