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= Bacon -- small RSpec clone.
"Truth will sooner come out from error than from confusion."
---Francis Bacon
Bacon is a small RSpec clone weighing less than 350 LoC but
nevertheless providing all essential features.
== Whirl-wind tour
require 'bacon'
describe 'A new array' do
before do
@ary =
it 'should be empty' do
@ary.should.not.include 1
it 'should have zero size' do
@ary.size.should.equal 0 0.1, 0.5
it 'should raise on trying fetch any index' do
lambda { @ary.fetch 0 }.
message.should.match(/out of array/)
# Alternatively:
should.raise(IndexError) { @ary.fetch 0 }
it 'should have an object identity' do
# Custom assertions are trivial to do, they are lambdas returning a
# boolean vale:
palindrome = lambda { |obj| obj == obj.reverse }
it 'should be a palindrome' do palindrome
it 'should have super powers' do
should.flunk "no super powers found"
Now run it:
$ bacon whirlwind.rb
A new array
- should be empty
- should have zero size
- should raise on trying fetch any index
- should have an object identity
- should be a palindrome
- should have super powers [FAILED]
Bacon::Error: no super powers found
./whirlwind.rb:39: A new array - should have super powers
6 specifications (9 requirements), 1 failures, 0 errors
If you want shorter output, use the Test::Unit format:
$ bacon -q whirlwind.rb
Bacon::Error: no super powers found
./whirlwind.rb:39: A new array - should have super powers
6 tests, 9 assertions, 1 failures, 0 errors
It also supports TAP:
$ bacon -p whirlwind.rb
ok 1 - should be empty
ok 2 - should have zero size
ok 3 - should raise on trying fetch any index
ok 4 - should have an object identity
ok 5 - should be a palindrome
not ok 6 - should have super powers: FAILED
# Bacon::Error: no super powers found
# ./whirlwind.rb:39: A new array - should have super powers
# ./whirlwind.rb:38
# ./whirlwind.rb:3
# 6 tests, 9 assertions, 1 failures, 0 errors
$ bacon -p whirlwind.rb | taptap -q
Tests took 0.00 seconds.
FAILED tests 6
6) should have super powers: FAILED
Failed 1/6 tests, 83.33% okay.
(taptap is available from
== Implemented assertions
* should.<predicate> and<predicate>
* should.equal
* should.match
* /
* should.raise(*exceptions) { }
* should.change { }
* should.throw(symbol) { }
* should.satisfy { |object| }
== Added core predicates
* Object#true?
* Object#false?
* Proc#change?
* Proc#raise?
* Proc#throw?
* Numeric#close?
== before/after
before and after need to be defined before the first specification in
a context and are run before and after each specification.
== Shared contexts
You can define shared contexts in Bacon like this:
shared "an empty container" do
it "should have size zero" do
it "should be empty" do
context "A new array" do
behaves_like "an empty container"
These contexts are not executed on their own, but can be included with
behaves_like in other contexts. You can use shared contexts to
structure suites with many recurring specifications.
== Matchers
Custom matchers are simply lambdas returning a boolean value, for
def shorter_than(max_size)
lambda { |obj| obj.size < max_size }
[1,2,3] shorter_than(5)
You can use modules and extend to group matchers for use in multiple
== bacon standalone runner
-s, --specdox do AgileDox-like output (default)
-q, --quiet do Test::Unit-like non-verbose output
-p, --tap do TAP (Test Anything Protocol) output
-o, --output FORMAT do FORMAT (SpecDox/TestUnit/Tap) output
-a, --automatic gather tests from ./test/, include ./lib/
-n, --name NAME runs tests matching regexp NAME
-t, --testcase TESTCASE runs tests in TestCases matching regexp TESTCASE
If you don't want to use the standalone runner, run
Bacon.summary_on_exit to install an exit handler showing the summary.
== Object#should
You can use Object#should outside of contexts, where the result of
assertion will be returned as a boolean. This is nice for
demonstrations, quick checks and doctest tests.
>> require 'bacon'
>> (1 + 1).should.equal 2
=> true
>> (6*9).should.equal 42
=> false
== Bacon with autotest
Since version 1.0, there is autotest support. You need to tag your
test directories (test/ or spec/) by creating an .bacon file there.
Autotest then will find it. bin/bacon needs to be in PATH or RUBYPATH.
== Converting specs
spec-converter is a simple tool to convert test-unit or dust style
tests to test/spec specs.
It can be found at
== Thanks to
* Michael Fellinger, for fixing Bacon for 1.9 and various improvements.
* Gabriele Renzi, for implementing Context#should.
* James Tucker, for the autotest support
* everyone contributing bug fixes.
== History
* January 7, 2008: First public release 0.9.
* July 6th, 2008: Second public release 1.0.
* Add Context#should as a shortcut for Context#it('should ' + _).
* describe now supports multiple arguments for better organization.
* Empty specifications are now erroneous.
* after-blocks run in the case of exceptions too.
* Autotest support.
* Bug fixes.
* XXX, 2008: Third public release 1.1.
* Add -Q/--no-backtraces to not details about failed specifications.
== Contact
Please mail bugs, suggestions and patches to
Git repository (patches rebased on HEAD are most welcome):
== Copying
Copyright (C) 2007, 2008 Christian Neukirchen <>
Bacon is freely distributable under the terms of an MIT-style license.
== Links
Behavior-Driven Development:: <>
RSpec:: <>
test/spec:: <>
Christian Neukirchen:: <>
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