Test Support

6.8

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Test Support

Kathryn Gray

1 Using Check Forms

2 GUI Interface

1 Using Check Forms

(require test-engine/racket-tests)

package: htdp-lib

This module provides test forms for use in Racket programs, as well as parameters to configure the behavior of test reports.

Each check form may only occur at the top-level; results are collected and reported by the test function. Note that the check forms only register checks to be performed. The checks are actually run by the test function.

syntax
(check-expect expr expected-expr)

Checks whether the value of the expr expression is equal? to the value produced by the expected-expr.

It is an error for expr or expected-expr to produce a function value or an inexact number.

syntax
(check-random expr expected-expr)

Checks whether the value of the expr expression is equal? to the value produced by the expected-expr.

The form supplies the same random-number generator to both parts. If both parts request random numbers from the same interval in the same order, they receive the same random numbers.

Examples:

> (check-random (random 10) (random 10))
> (check-random
(begin (random 100) (random 200))
(begin (random 100) (random 200)))
> (test)
Both tests passed!

If the two parts call random for different intervals, they are likely to fail:

Examples:

> (check-random
    (begin (random 100) (random 200))
    (begin (random 200) (random 100)))
> (test)
Ran 1 check.
0 checks passed.
Actual value differs from the expected value.
    Actual value: 25
  Expected value: 12
At line 2 column 0

It is an error for expr or expected-expr to produce a function value or an inexact number.

syntax
(check-satisfied expr property?)

Checks whether the value of the expr expression satisfies the property? predicate (which must evaluate to a function of one argument).

Examples:

> (check-satisfied 1 odd?)
> (check-satisfied 1 even?)
> (test)
Ran 2 checks.
1 of the 2 checks failed.
Actual value 1 does not satisfy "even?".
At line 3 column 0

Changed in version 1.1 of package htdp-lib: allow the above examples to run in BSL and BSL+

syntax
(check-within expr expected-expr delta-expr)

delta-expr : number?

Checks whether the value of the test expression is structurally equal to the value produced by the expected expression; every number in the first expression must be within delta of the corresponding number in the second expression.

It is an error for expr or expected to produce a function value.

syntax
(check-error expr)
(check-error expr msg-expr)

msg-expr : string?

Checks that evaluating expr signals an error, where the error message matches the string (if any).

syntax
(check-member-of expr expected-expr ...)

Checks whether the value of the expr expression is equal? to any of the values produced by the expected-exprs.

It is an error for expr or any of the expected-exprs to produce a function value or an inexact number.

syntax
(check-range expr min-expr max-expr)

   expr : number?
   min-expr : number?
   max-expr : number?

Checks whether value of expr is between the values of min-expr and max-expr inclusive.

syntax
(test)

Runs all of the tests specified by check forms in the current module and reports the results. When using the gui module, the results are provided in a separate window, otherwise the results are printed to the current output port.

parameter
(test-format)
→
(or/c (-> any/c (or/c (is-a?/c snip%) string?))
      (-> any/c output-port? void?))
(test-format format) → void?
   format :
(or/c (-> any/c (or/c (is-a?/c snip%) string?))
      (-> any/c output-port? void?))

A parameter that stores the formatting function for the values tested by the check forms.

If the parameter is a function of two arguments, then it is supplied the value and an output port to render the value to. Otherwise, if it is a function of one argument, then the resulting string is used to render the value.

The default value accepts two arguments and prints the any/c argument to the given port.

parameter
(test-silence) → boolean?
(test-silence silence?) → void?
silence? : any/c

A parameter that stores a boolean, defaults to #f, that can be used to suppress the printed summary from test.

parameter
(test-execute) → boolean?
(test-execute execute?) → void?
execute? : any/c

A parameter that stores a boolean, defaults to #t, that can be used to suppress evaluation of test expressions.

2 GUI Interface

(require test-engine/racket-gui)

package: htdp-lib

This module requires produces an independent window when displaying test results. It provides the same bindings as test-engine/racket-tests.

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