These are assertions (or matchers) for SUnit written for cuis Smalltalk inspired by some of the marchers of RSpec.
Just import it, these matchers extends TestCase.
self assert: [ aCollection add: 1 ] changes: [ aCollection size ]
Also the opposite is included:
self assert: [ aCollection sum ] doesNotChange: [ aCollection size ]
And the parametric versions:
self assert: [ aCollection add: 1; add: 2 ] changes: [ aCollection size ] by: 2
aCollection := OrderedCollection with: 1.
self assert: [ aCollection add: 2 ] changes: [ aCollection size ] from: 1 to: 2
self assert: (0.3) isNearTo: (0.1 + 0.2)
self assert: originalNumber isNearTo: newValue withPrecision: precision
Also you have the negative assertions:
self assert: originalNumber isNotNearTo: newValue
self assert: originalNumber isNotNearTo: newValue withPrecision: precision
self assert: #() includes: 1
Will raise a nice error message