9 Testing Servlets

▼ |  | Web Applications in Racket

1 | Running Web Servlets
2 | Stateful Servlets
3 | Stateless Servlets
4 | HTTP: Hypertext Transfer Protocol
5 | URL-Based Dispatch
6 | Formlets: Functional Form Abstraction
7 | Templates: Separation of View
8 | Page: Short-hand for Common Patterns
9 | Testing Servlets
10 | Troubleshooting and Tips
| Index

On this page:

tester/ c
make-servlet-tester
make-dispatcher-tester

Racket
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## 9 Testing Servlets🔗ℹ

(require web-server/test) | package: web-server-lib

The Web Server provides a simple facility for writing tests for Web servlets and dispatchers.

The core functionality allows a request to be sent to the servlet and the response captured:

> value tester/c : contract?

This contract is equivalent to

> (->* ()
> ((or/c string? url? request? false/c)
> (listof binding?)
> #:raw? boolean?
> #:headers? boolean?)
> (or/c bytes?
> xexpr?
> (cons/c bytes?
> (or/c bytes?
> xexpr?))))

It represents a function that accepts a request and returns the answer the servlet for that request. This interaction function has many possible calling patterns:

- No arguments: a call to the root URL path with no bindings.

- At least one argument: this may be a string, URL, or a request data structure.

- Two arguments: the first argument must be a string or a URL, but the second argument can specify the request bindings.

- The optional #:raw? keyword controls whether an X-expression or a byte string is returned as a result.

- The optional #:headers? keyword controls whether the headers are included in the return value as a byte string. When this is used, the two returns are returned in a cons.

> procedure (make-servlet-tester servlet) → tester/c
> | servlet |  | : |  |
> (-> request?
> can-be-response?)

This function accepts a servlet function and provides a tester function as described above. It is equivalent to (make-dispatcher-tester (dispatch/servlet servlet)), so if you need custom arguments to dispatch/servlet, use make-dispatcher-tester.

> procedure (make-dispatcher-tester d) → tester/c
> d : dispatcher/c

This function accepts a dispatcher and provides a tester function as described above.

This facility is designed to be used in concert with a technique of extracting continuation URLs and relevant values; xml/path is one way to do this. Here is an extended example that tests an Add-Two-Numbers.com:

> (define (test-add-two-numbers -s>)
> (define x (random 500))
> (define xs (string->bytes/utf-8 (number->string x)))
> (define y (random 500))
> (define ys (string->bytes/utf-8 (number->string y)))
> (define r0 (-s>))
> (define k0 (se-path* '(form #:action) r0))
> (define i0 (se-path* '(form input #:name) r0))
> (define r1
> (-s> (format "~a?~a=~a" k0 i0 xs)
> (list (make-binding:form (string->bytes/utf-8 i0) xs))))
> (define k1 (se-path* '(form #:action) r1))
> (define i1 (se-path* '(form input #:name) r1))
> (define r2
> (-s> (format "~a?~a=~a" k1 i1 ys)
> (list (make-binding:form (string->bytes/utf-8 i1) ys))))
> (define n (se-path* '(p) r2))
> (check-equal? n
> (format "The answer is ~a" (+ x y))))
> (require
> (prefix-in ex:add1: web-server/default-web-root/htdocs/servlets/examples/add)
> (prefix-in ex:add2: web-server/default-web-root/htdocs/servlets/examples/add-v2))
> (test-add-two-numbers
> (make-servlet-tester ex:add1:start))
> (test-add-two-numbers
> (make-servlet-tester ex:add2:start))

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