▼Expect:   First Class Assertions
On this page:
check-expect
check-eq?
check-eqv?
check-equal?
check-not-eq?
check-not-eqv?
check-not-equal?
check-pred
check-=
check-true
check-false
check-not-false
check-exn
check-not-exn
check
test-subject
fail-check/  expect
8.12
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2 Using Expectations with RackUnit🔗ℹ

 (require expect/rackunit) package: expect

This module defines how to use expectations with the rackunit testing framework. Included are custom checks and test forms that test values using expectations, as well as expectation-using replacements for the various built in checks provided by rackunit.

If you have an existing set of RackUnit tests, simply change (require rackunit) to (require expect/rackunit). Only checks are exported by expect/rackunit; if your tests use other exports of rackunit you’ll need to use only-in to import them from RackUnit.

procedure

(check-expect v exp [message]) → void?

  v : any/c
  exp : any/c
  message : string? = ""
Checks that v has no faults according to exp, with message added to the check info stack in the event of failure. The given exp is converted to an expectation with ->expectation.

Examples:
> (check-expect 1 (expect-pred number?))
> (check-expect 'foo (expect-pred number?))

--------------------

FAILURE

name:       check-expect

location:   eval:2:0

actual:     'foo

expected:   number?

Expected a different kind of value

--------------------

> (check-expect #hash((a . (1 WRONG 3)) (b . (4 5 WRONG)))
                #hash((a . (1 2 3)) (b . (4 5 6))))

--------------------

FAILURE

name:       check-expect

location:   eval:3:0

actual:     '#hash((a . (1 WRONG 3)) (b . (4 5 WRONG)))

fault:

  summary:    expected a different value

  actual:     'WRONG

  expected:   equal? to 2

  context:

    in:         value for key 'a

    in:         item at position 1

fault:

  summary:    expected a different value

  actual:     'WRONG

  expected:   equal? to 6

  context:

    in:         value for key 'b

    in:         item at position 2

Multiple faults found

--------------------

value

check-eq? : procedure?

value

check-eqv? : procedure?

value

check-equal? : procedure?

value

check-not-eq? : procedure?

value

check-not-eqv? : procedure?

value

check-not-equal? : procedure?

value

check-pred : procedure?

value

check-= : procedure?

value

check-true : procedure?

value

check-false : procedure?

value

check-not-false : procedure?

value

check-exn : procedure?

value

check-not-exn : procedure?

value

check : procedure?

Custom checks that are equivalent to their corresponding rackunit checks except that they are defined in terms of expectations, and provide better error messages for most failures. None of these checks accept expectations as arguments.

Example:
> (check-equal? '(1 2 3 foo 5) '(1 2 3 4 5))

--------------------

FAILURE

name:       check-equal?

location:   eval:1:0

subject:    (1 2 3 foo 5)

actual:     'foo

expected:   equal? to 4

context:

  in:         item at position 3

Expected a different value

--------------------

syntax

(test-subject maybe-name
  #:subject subject-expr
  expectation-expr ...)
 
maybe-name = 
  | name-str
 
  subject-expr : any/c
  expectation-expr : any/c
Creates a test-case or test-begin form containing one check-expect expression for each expectation-expr. The subject-expr is evaluated once and the resulting value is passed as the value to test by each check-expect expression. If name-str is provided, it must be a string and the resulting test is a test-case with name-str as its name, otherwise it is a test-begin form. Note that each expectation-expr is converted to an expectation by check-expect.

Example:
> (test-subject "addition" #:subject +
    (expect-call (arguments 1 2 3) (expect-return 6))
    (expect-call (arguments) (expect-return 0))
    (expect-call-exn (arguments 'foo) #rx"contract")
    (expect-call (arguments 5 10) (expect-return 16)))

--------------------

addition

FAILURE

name:       test-expect

location:   eval:1:0

subject:    #<procedure:+>

actual:     15

expected:   equal? to 16

context:

  in:         call with (arguments 5 10)

  in:         the return value

Expected a different value

--------------------

procedure

(fail-check/expect v exp) → void?

  v : any/c
  exp : any/c
Essentially equivalent to (check-expect v exp), except as an ordinary function that raises an exn:test:check exception. Check infos containing the faults raised by exp are added to the exception, but no other infos (such as 'expression) are included. Like check-expect, if exp is not an expectation it is converted to one with ->expectation.

Example:
> (fail-check/expect 'foo (expect-pred number?))

Expected a different kind of value

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