Test Driven JavaScript Development- P25

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Test Driven JavaScript Development- P25:This book is about programming JavaScript for the real world, using the techniques and workflow suggested by Test-Driven Development. It is about gaining confidence in your code through test coverage, and gaining the ability to fearlessly refactor and organically evolve your code base. It is about writing modular and testable code. It is about writing JavaScript that works in a wide variety of environments and that doesn’t get in your user’s way.

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  1. 17.3 Fighting Bugs in Tests 473 17.3 Fighting Bugs in Tests Developers who are unfamiliar with unit testing often ask “how do you test your tests?” The answer, of course, is that we don’t. That does not imply that we do not take measures to reduce defects in tests. The most important way to reduce the chance of bugs in tests is to never implement logic in tests. A unit test should be a sim- ple sequence of assignments and function calls followed by one or more assertions. Apart from keeping tests stupid, the most important tool to catch erroneous tests is to write and run them before implementing the passing code. 17.3.1 Run Tests before Passing Them When tests are written before the required production code, they should also be run before passing it. Doing so allows us to verify that the test fails for the expected reasons, thus giving us a chance to catch errors in the test itself. Failing a test with an articulated expectation as to how and why the test should fail is in fact the most effective means with which we can fight buggy tests. Skipping this point, we might move on to pass the test immediately. As soon as we have started writing production code, we are a lot less likely to discover faulty testing logic and might as well end up passing the test, thus sneaking the wrong behavior into production code without having tests that can tell us as much. 17.3.2 Write Tests First To be able to run tests before passing them we obviously need to write them first as well. Because this book has given some insight into the test-driven development cycle and how it can apply to JavaScript, the recommendation to write tests first should not come as a surprise. Writing tests upfront has benefits beyond making it easier to catch faulty tests. Tests first ensure that code is inherently testable. If you have ever attempted to retrofit unit tests onto code that was not originally written with testability in mind, you will appreciate the importance of testable code. Writing testable code is not useful only to test it. Unit tests are secluded sample uses of production code, and if writing a test for any given behavior is hard, well, then using that particular behavior is hard. If using a small part of the code base requires half an application’s worth of setup, then the design might not be optimal. For example, requiring a DOM element and its CSS API in order to transition a color from red to green is a good example of code that is hard to use for the same reasons as why it is hard to test. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  2. 474 Writing Good Unit Tests Ensuring that code is testable means ensuring it is loosely coupled and well factored, thus flexible and easy to use, both as a whole and in parts. Writing tests upfront as we do in test-driven development builds testability into the code. 17.3.3 Heckle and Break Code Sometimes a test suite will be all green, yet the production code clearly exhibits defects. The source to these kinds of errors are often found in the integration between moving parts of the application, but sometimes they can be the result of edge cases not catered for, or worse, bugs in tests. A great way to smoke out errors in tests and generally assess the quality of a test suite, is to intentionally introduce errors in production code and then make sure the tests fail, and for the right reasons. The following “attacks” can prove useful to find deficiencies in tests. • Flip the value of boolean expressions. • Remove return values. • Misspell or null variables and function arguments. • Introduce off-by-one errors in loops. • Mutate the value of internal variables. For each intentional deficiency you introduce, run the tests. If they all pass, you know that you have either stumbled upon untested code or code that simply doesn’t do anything. Either capture the bug with a new unit test or remove the offending code, and continue. 17.3.4 Use JsLint JsLint1 is a “JavaScript Code Quality Tool.” Inspired by lint for C, it detects syntac- tical errors, bad practices, and generally provides many more warnings than most JavaScript runtimes do today. Syntax errors can cause weird problems in test cases. A misplaced semicolon or comma can cause only some of your tests to run. Mak- ing matters worse, the test runner may not be able to warn you about some tests not being run. Using JsLint both on production code and tests alike will help you remove typos and other syntax errors, making sure the tests run as expected. 1. http://www.jslint.com/ Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  3. 17.4 Summary 475 17.4 Summary In this final chapter we have reviewed some simple guidelines that can help improve the quality of unit tests. Tests, when done right are a great asset, but bad tests can be worse than no tests because they introduce a significant overhead in maintenance and complicate working with code without providing any real value. The guidelines presented throughout this chapter were divided into three groups: techniques to improve readability, an important quality of a good unit test; techniques to generate true unit tests that stay at the unit level; and last, techniques that help avoid buggy tests. By working through the example projects in Part III, Real-World Test-Driven Development in JavaScript, and viewing them from a wider angle both in this chapter and the previous, you should have gained a good understanding of what unit testing and test-driven development is—and isn’t. Now it is up to you. The only way to get better is to gain as much experience as possible, and I urge you to start practicing immediately. Create your own learning tests, add features to the example projects from the book, or start new projects of your own using TDD. Once you have grown comfortable within the process that is test-driven development, you won’t go back—you will become a happier and more productive developer. Good luck! Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
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  5. Bibliography [1] Martin Fowler. Refactoring: Improving the Design of Existing Code. Addison-Wesley, 1999. [2] Hamlet D’Arcy. Forgotten refactorings. http://hamletdarcy.blogspot.com/2009/06/ forgotten-refactorings.html, June 2009. [3] Kent Beck. Test-Driven Development By Example. Addison-Wesley, 2002. [4] Wikipedia. You ain’t gonna need it. http://en.wikipedia.org/wiki/You ain’t gonna need it. [5] Douglas Crockford. JavaScript: The Good Parts. O’Reilly Media, 2008. [6] Douglas Crockford. Durable objects. http://yuiblog.com/blog/2008/05/24/durable- objects/, May 2008. [7] Gerard Meszaros. xUnit Test Patterns: Refactoring Test Code. Addison-Wesley, 2007. 477 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
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  7. Index A error handling with, 325–327 acceptance test-driven development, 34 event data looping with, 327 access tokens, 381–382, 385–386 expectations for, 323 embeds for, 385–386 notifications with, 324–325 updates for, 385 observers with, 325–329 ActionScript, 159 public objects with, 326 activateTab method, 190–192 server connections with, 329–338 event delegation in, 190 setup for, 323 implementation of, 192 ajax.loadFragment method, 94 tag name in, 190 ajax.poll, 453 testing for, 190–191 Ajax Push, 314 activation object, 82 anonymous closures, 146 Active X objects, 252 anonymous function expression, 74, 101–107. identificators for, 252 See also namespaces addEventHandler method, 206 ad hoc scopes, 101–103 custom event handlers, 212–213 immediately called, 101–107 addMessage, 361–363 namespaces, 103–107 as asynchronous, 365–366 anonymous mocks, 454 callbacks with, 361–362 anonymous proxy function, 95 event emitters with, 374 APIs. See application programming interfaces promise refactoring with, 367–371 application programming interfaces (APIs), testing implementation for, 366 247–249, 269–277. See also DOM UIDs for, 362–363 manipulation updating of, 369 AJAX, 269–277 ad hoc scopes, 101–103 integration test for, 269–271 avoiding the global scope, 101–102 local requests for, 273–274 lightboxes and, 101–102 send method and, 271 with nested closures, 103 status testing for, 274–277 simulation of, 102–103 TDD and, 247 AJAX. See Asynchronous JavaScript testing results for, 270–271 and XML apply method, 75, 77 ajax.cometClient, 323–338 summing numbers with, 91 data delegation with, 324–325 this keyword and, 90 data dispatching with, 323–327 arbitrary events, 241–246 479 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  8. 480 Index arbitrary events (Continued ) testing for, 10 notify method, 243–245 in unit tests, 465–466 observe method, 241–242 Asynchronous JavaScript and XML (AJAX), arbitrary objects, 235–241 247–292. See also GET requests; POST inheritance motivations, 235 Requests observable behavior for, 235–236 Ajax Push, 314 renaming methods and, 240–241 APIs, 247–249, 269–277 arguments, 97–99 baseline interfaces for, 290 binding functions with, 97–99 browser inconsistencies with, 248 bind method and, 97–99 development strategy for, 248 formal parameters v., 173 directions for, 291 in memoization, 114 directory layout for, 249 passing, 231–232 duplication with, 292 setTimeout method and, 97 GET requests, 255–268 arguments object, 77–80, 153 goals of, 248–249 accessing properties in, 79 implementation review for, 290 array methods and, 78–79 JsTestDriver and, 249–250 dynamic mapping of, 79–80 namespaces for, 256, 290 formal parameters, 78–80 onreadystatechangehandler and, modifications of, 79 266–267 structure of, 78 POST requests, 277–287 array literals, 118 refactoring with, 292 Array.prototype, 121–122 request APIs and, 247–249, 288–292 Enumerable module in, 157 request interfaces and, 249–250 method addition to, 122 restoring of, 258 native object extension for, 122 Reverse Ajax, 314 Array.prototype.splice method, source files for, 256 56–58 stubbing and, 248–249 arrays, 56 TDD and, 292 browser consoles, 57 tddjs.ajax.create method and, programming, 58 253–254 removed item returns, 57 test cases for, 292 traditional testing, 56 XMLHttpRequest object and, 247–249 arrays asynchronous tests, 35 addObserver method and, 229 sleep function in, 35 arguments object and, 78–79 unit tests and, 35 Array.prototype.splice method, 56 automated stubbing, 258–260, 262–263 in ECMAScript 5, 175–176 helper method extraction with, 258–259 enumerable properties, 123 open method, 259–260 hard-coding, 225 stub helper and, 259 in observer patterns, 224–225 automated testing, 3–19. See also unit tests with obsolete constructors, 238 assertions, 9–10 for refactoring, 226 debugging with, 3 spliced, 57 development of, 3–4 for this keyword, 88 functions, 11–12 assert function, 74 green, as symbol for success, 10 assertions, 9–10, 36 integration tests, 14–16 for controllers, 347 JsUnit, 4 functions of, 9 red, as symbol for failure in, 10 JsTestDriver, 51–52 setUp method, 13–14 in POST requests, 283 TDD, 30 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  9. Index 481 tearDown method, 13–14 exceptions for, 233 unit tests, 4–10, 16–18 non-callable arguments and, 232 preconditions for, 233 B bootstrap scripts BDD. See behavior-driven development in chat client model, 430 Beck, Kent, 21 message lists and, 421 behavior-driven development (BDD), 33–34 static files and, 410–411 TDD, 34 bottlenecks, in performance tests, 68–69 user stories in, 34 DOM implementation in, 69 xUnits and, 33 Firebug, 68 behavior verification, of test doubles, 442–443 locating, 68–69 inspection of, 443 profiling, 68–69 isolation of behavior from, 470–472 box-shadow property, 209 by mocks, 457, 470–472 browser sniffing, 199–207. See also object stubbing and, 451–452, 470–472 detection, in browser sniffing tailored asserts for, 451 event listening fixes in, 198–199 unit tests as, 465–466, 468–472 libraries and, 200 benchmarks, 60–69 object detection in, 199–206 binding functions and, 98 problems with, 200 definition of, 60 state of, 200 DOM manipulation in, 68 testing in, 207 Function.prototype in, 65–66 updating of, 200 functions for, 65 user agent sniffing and, 198–199 highlighting in, 67–68 integration of, 64 C loops for, 61–63, 66 cache issues, with long polling, measuring of, 67–68 319–320 reformatting of, 66 buster additions, 319–320 runners for, 61 URLs and, 319–320 setup for, 64 callable host objects, 203–204 tools for, 64–65 callbacks, 308–311 use of, 66–67 with addMessage, 361–362 in Windows Vista, 61 complete, 300–302, 311 binding functions, 93–100 defaults, 310 anonymous proxy functions and, 95 in domain models, for Node.js, 358 with arguments, 97–99 failure, 310–311 benchmarks and, 97 nested, 367 bind method, 95–97 for onreadystatechangehandler, currying and, 99–100 266–268 Function.prototype.bind, 95–96 polling, for data, 308–311 lightbox examples of, 93–95 with server connections, 333 setTimout method, 97 static files and, 409 this keyword and, 93–96 success, 309–310 bind method, 95–97 tddjs.ajax.poller and, 300–302 arguments and, 97–99 calling, of functions, 77–80 closure and, 96 arguments object, 77–79 implementation of, 96 direct, 77–80 optimized, 98–99 call method, 75, 77 use of, 96 this keyword and, 89 bogus headers, 308 call order documentation, 234–235 bogus observers, 232–233 as feature, 234 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  10. 482 Index cascading style sheets (CSS), 208–210 format messaging with, 321–322 box-shadow property in, 209 HTML5 streaming, 315 feature testing of, 208–210 JSON response with, 322 static files and, 410 limitations of, 314, 321 style properties in, 209–210 with observable objects, 321 support detection of, 209 server connections with, 329–338 chat client model, for DOM manipulation, XMLHttpRequest streaming, 315 429–434 command line productivity, 51 application styling of, 430–431 CommonJs modules, 341, 345 bootstrapping script in, 430 CommonJs testing frameworks, 40–41 compression in, 434 complete callbacks, 300–302, 311 deployment notes in, 433–434 scheduling of, 302 design of, 430–431 specifications of, 301–302 input field clearance in, 432–433 console.log method, 76 message forms in, 429 constructors, 130–136. See also prototypes scrolling in, 431–432 broken properties of, 134 user testing of, 430–433 circle object, 139 chatRoom, 372–375 ECMA-262 and, 136 property descriptors for, 373 instanceof operators, 136 Circle hybrid, 168–169 missing properties for, 134–135 circle objects, 88, 152 misuse of, 135–136 Circle.prototype, 132–134, 136–137, 143 objects from, 130–132, 239–240 assignments for, 133 in observer patterns, 223 failing assertions for, 133–134 private methods for, 146–147 Sphere.prototype and, 138 problems with, 135–136 _super method, 143 prototypes, 130–135 testing for, 133 continuous integration, 34–35 circular references for JavaScript, 34–35 assertions of, 272 minifying code with, 35 breaking of, 272–273 controllers, 345–357, 378–386 with XMLHttpRequest object, 271–272 access tokens and, 381–382, 385–386 clean code, in TDD, 28 application testing, 356–357 closure application testing for, 386 ad hoc scopes, 103 assertions for, 347 anonymous, 146 body of, 386 in anonymous proxy function, 95 closing connections for, 355–356 bind method and, 96 closing responses for, 356 functions and, 84 CommonJs modules, 345 for onreadystatechangehandler, 267 creation of, 346–347 private methods and, 145 done method, 346 code paths, from stubbing, 444–445 duplications with, 350, 353 Comet, 314–315, 321–338. See also event handlers and, 352 ajax.cometClient; server expectations for, 345 connections formatting messages with, 383–385 ajax.cometClient, 323–338 GET requests and, 380–386 browsers with, 321 JSON and, 347–350 client interface with, 322 malicious data with, 354 data publishing with, 338 message extraction with, 351–354 drawbacks to, 314 message filters, 381–382 feature tests for, 338 with message lists, 411–412 forever frames and, 314–315 module definition, 345–346 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  11. Index 483 MVC, 391 debugging with Node.js, 345–357, 378–386 assertions and, 9 POST messages, 347–354 with automated testing, 3 post method completion with, decoupled code, 22 378–380 decrementing functions, 84 request bodies with, 348–351 dedicated respond method, 383 request responses with, 354–356 dependencies, 37 respond method, 382–383, 386 Dojo libraries, 40 response codes for, 355 domain models, for Node.js, 358–366 response headers, 386 addMessage in, 361–363 servers, 356–357 asynchronous interfaces, 358 setup for, 351 bad data in, 359–361 status codes for, 354–355 callbacks in, 358 stubbing with, 348–349, 353 chart room creation, 358 tabController object, 187–190 getMessageSince method, tab controllers, 192–196 363–365 testing for, 346 I/O interface, 358 in user forms, 392–393 messages in, 359–366 Crockford, Douglas, 148, 175, 333 usernames in, 359–361 cross-browser event handling, 210–213 DOM events, 42, 207–208 addEventHandler method in, in benchmarks, 68 212–213 in bottlenecks, 69 custom events in, 211–213 feature detection in, 207–208 feature detection for, 210–211 feature testing in, 207–208 normalization in, 211 in IE, 207 cross-browsers in lightbox objects, 94 event handlers, 210–213 observer patterns and, 220 IDE, 17 DOM manipulation, 389–434. See also chat crosscheck, 42 client model, for DOM manipulation; cross site scripting (XSS) protection, 418 message forms; message lists, with DOM CSS. See cascading style sheets manipulation; user forms currying, 99–100 approaches to, 390–391 binding v., 99 chat client model with, 429–434 implementation of, 100 client display, 391 directory structure for, 390 D JsTestDriver configuration in, 390 Dahl, Ryan, 341 message forms with, 422–429 data publishing, with Comet, 338 message lists with, 411–421 data streaming, 293–339. See also Comet; MVC and, 391 polling, for data; server connections; MVP and, 391 tddjs.ajax.poller passive view and, 391 with Comet, 314–315, 321–338 static files in, 408–411 long polling for, 315–320 TDD and, 389–434 polling for, 294–313 user forms and, 392–408 server connections and, 329–338 done method, 346 with Server Push, 293 DontDelete attribute, 126 TDD and, 293 DontEnum attribute, 126–128 Date.formats.j method, 14 IE, 127 Date.prototype.strftime, 7 overriding properties for, 127 JsTestDriver, 47–48 dot notation, 118 day of year calculations, 15 dummy objects, 441 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  12. 484 Index duplication server connections and, 333 with AJAX, 292 set function, 161 with controllers, 350, 353 setters in, 166–167 status testing, for APIs, 274–275 shortcuts in, 164 in TDD, 28 standard codification for, 160 test removal, 229–230 strict mode in, 160, 171–174 with unit test, 467–468 tddjs.extend method and, 156 for XMLHttpRequest object, 253 this keyword and, 90–91 writable function, 161 encapsulation, 145–150 E private members and, 147–148 Eclipse, 49–51 private methods and, 145–147 JsTestDriver installation, 49–50 privileged methods and, 147–148 running tests, 50–51 radius property in, 148 ECMA-262, 58, 118 Enumerable module, 157–158 constructors and, 136 Array.prototype in, 157 properties and, 126 in ECMAScript 5 object models, 161 prototypal inheritance and, 138 enumerable properties, 122–126 in prototype chains, 119 looping arrays, 123 ECMAScript 5, 25, 58, 159–176. See also strict Object.prototype.hasOwnProperty, mode, in ECMAScript 5 124–126 ActionScript and, 159 running tests with, 123 additions to, 174–176 env.js library, 42 arrays in, 175–176 errback conventions, in Node.js, 358 backwards compatibility in, 159–160 error handling, 232–235 browser extensions in, 160 with ajax.cometClient, 325–327 Circle hybrid in, 168–169 bogus observer additions and, empowered properties, 162 232–233 Enumerable module and, 161 call order documentation and, 234–235 in execution contexts, 81 forever frames and, 314 Firefox and, 160 misbehaving observers and, 233–234 Function.prototype and, 95 event emitters, 372–378 Function.prototype.bind method addMessage with, 374 in, 175 chatRoom with, 372–375 get function, 161 getMessageSince method, 376 getters in, 166–167 waitForMessagesSince method, in global object, 82 375–378 Google Chrome and, 160 event handlers, 102–103 improvements to, 174–176 controllers and, 352 JScript.Net and, 159 cross-browsers, 210–213 JSON in, 175 handleSubmit method, 397–398 name/value assignment in, 161–162 in object detection, 201 Object.create method in, tabController object in, 187–188 165–168 unit tests and, 466 object models and, 161–171 in unobtrusive JavaScript, 179 Object.seal implementation in user forms, 394–395 in, 163 event listeners, 394–398 property attributes, 161–163, 167–170 application code for, 394–395 property descriptor changes in, 162 events. See arbitrary events; cross-browser event prototypal inheritance in, 164–166 handling; event handlers reserved keywords in, 170–171 execution context, 80–81 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  13. Index 485 ECMAScript specification, 81 object extension in, 149–150 this keyword and, 88 patterns, 149 variable object in, 81–82 private variables with, 150 expression, functions, 74–75, 84–87 Sphere.prototype and, 150 anonymous, 74 Function.prototype, 65–66, 75–78 conditional declarations in, 85 apply method, 75, 77 conditional definitions in, 85 binding functions and, 95–96 feature detection and, 85 call method, 75, 77 hoisting in, 85 ECMAScript 5 and, 95 named, 75, 86–87 function creation, 77 punctuation for, 75 Function.prototype.bind method, 175 String.prototype.trim method and, 85 Function.prototype.inherit functions, 152–153 F functions, 73–91. See also anonymous function Facebook, 294 expression; arguments object; binding failure callbacks, 310–311 functions; expression, of functions; stateful fake objects, 440–441 functions; this keyword feature detection, 85, 197–215 activation object and, 82 Browser sniffing, 199–207 anonymous proxy, 95 for Comet, 338 arguments object and, 77–80 for cross-browser event handling, 210–213 assert, 74 in DOM events, 207–208 binding, 93–100 IE browsers and, 213 calling of, 77–80 for long polling, 320 closure and, 84 for message forms, 428–429 declarations of, 73–74 for message lists, 420 decrementing, 84 script production in, 215 definitions of, 73–77 self-testing code, 215 execution contexts, 80–81 in strftime, 214 expression of, 74–75, 84–87 stubbing and, 263 formal parameters of, 74 undetectable features, 214 free variables, 84 uses of, 213–214 Function.prototype, 75–78 for XMLHttpRequest object, 254 global object and, 82–83 Fibonacci sequence, 112–114 hoisting of, 82, 85 alternative versions of, 113 incrementing, 84 Firebug, 68–69 length property, 76 console.log method in, 76 Object.prototype, 75 profiler for, 69 scope, 80–84 Firefox stateful, 107–112 ECMAScript 5 and, 160 this keyword, 87–91 integration tests with, 270–271 function scope, 80 for, as enumerable property, 123 forever frames, 314–315 G error handling and, 314 Geisendorfer, Felix, 408 ¨ for-in, as enumerable property, 123–124 getMessageSince method, 363–365 format specifiers, 15–16 addition of, 364 Fowler, Martin, 17, 391 message retrieval testing with, 363–365 functional inheritance, 148–150 with promises, 372 definition of, 148 proxy for, 376 durable objects and, 149 getPanel function, 193–195 implementation of, 148–149 toggles in, 193–194 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  14. 486 Index GET requests, 255–268 in IE, 202 automated stubbing and, 258–260, 262–263 unfriendly, 203 controllers and, 380–386 HTML5 streaming, 315 formatting messages with, 383–385 Hypertext Markup Language (HTML), 269–271 improved stubbing and, 261–263 in Comet, streaming for, 315 manual stubbing and, 257–258 integration testing, 269–271 onreadystatechangehandler, 263–268 in JsTestDriver, 400 POST requests and, 285–287 in static files, 409–410 respond method, 382–384 in unobtrusive JavaScript, 177 stubbing, 257–263 user form embedding with, 400–401 tddjs.ajax.create object and, 255 URL requirement for, 255–256 I getters, 166–167 IDE. See integrated development environment Giammarchi, Andrea, 208 IE. See Internet Explorer global object, 82–83 immediately called anonymous functions, Array.prototype and, 122 101–107 ECMAScript in, 82 ad hoc scopes and, 101–103 property assignment in, 83 punctuation and, 101 this keyword in, 88 improved stubbing, 261–263 window and, 83 in-browser test frameworks, 37–43. See also global scope, 80, 101–102 YUI test Gmail, unobtrusive JavaScript in, 184 disadvantages of, 42–43 Gnome Shell, 160 Dojo, 40 Google Chrome, 160 headless, 41–42 green, as symbol for success in unit testing, 10 JsTestDriver, 43–51 GTalk, 294 JsUnit, 37, 40 Prototype.js, 40 H QUnit, 40 handleSubmit method, 397–398, 401–402, URL query string, 37 404 YUI test, 38–40 message forms and, 425 incrementing functions, 84 hard-coding, 27, 225–226 inheritance models, 119–120 in addObserver method, 227 Object.create method, 151 for arrays, 225 inputs for inputs, 27 for hard-coding, 27 for outputs, 27 in TDD, 24–25 headers, in data polling, 308–311 instanceof operators, 136 bogus, 308 integrated development environment (IDE), 17, passing on, 309 49–51. See also Eclipse headless testing frameworks, 41–42 Eclipse, 49–51 crosscheck, 42 IntelliJ IDEA, 49 DOM implementation, 42 JsTestDriver, 49–51 env.js library, 42 integration tests, 14–16 issues with, 42 for APIs, 269–271 Rhino, 42 Date.formats.j method, 14 Heilmann, Chris, 178 for day of year calculations, 15 hoisting, of functions, 82, 85 with Firefox, 270–271 host objects, 202–204 format specifiers in, 15–16 callable, 203–204 high-level, 14 ECMAScript specification in, 202 HTML document testing, 269 feature detection in, 204 script for, 269–270 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  15. Index 487 IntelliJ IDEA, 49 configuration files for, 249–250 Internet Explorer (IE), 127–128 configuration for, 48 addObserver method, 228 Date.prototype.strftime, 47–48 DOM events in, 207 disadvantages of, 44 DontEnum attribute in, 127 in DOM manipulation, 390 feature detection and, 213 functions of, 43–44 host objects in, 202 HTML in, 400 named function expressions in, 86–87 IDE, 49–51 Object.defineProperty in, 166 Jar file, 44–45 XMLHttpRequest object and, 252 Linux testing, 48 I/O interfaces, 358 load paths, 46 iterators, 109–112 observer patterns and, 221 closures, 109 OSX testing, 48 functional approach to, 111–112 plug-ins, 43 looping with, 112 polling data and, 295 tddjs.iterator method, 109–111 project layout for, 249–250 running tests for, 46–48 J server connections and, 333 Jar file, 44–45 setup, 44–49 on Linux, 45 starting servers for, 45–46 starting servers, 45–46 TDD and, 48–49 for Windows users, 45 timer testing, 303–308 JavaScript. See also Asynchronous JavaScript uid’s and, 108 and XML; Node.js; unobtrusive JavaScript updating of, 262 ECMAScript 5 in, 25 user form configurations, 404 JsLint, 474 Windows testing for, 48 Mozilla, 58 JsUnit observer pattern in, 220–221 in In-Browser test frameworks, 37 programming of, 58–59 testing frameworks, 4, 37, 40 unit tests, 55–60 timer testing, 303–304 unobtrusive, 177–196 writing cross-browser code in, 197 L JavaScriptCore, 58 learning tests, 56, 59–60 JavaScript dates, 5–9 bugs and, 59 strftime for, 5–9 frameworks, 60 jQuery new browsers, 59 performance tests, 69 wisdom from, 59 tabbed panels, 196 lightbox objects, 93–95 in unobtrusive JavaScript, 195–196 ad hoc scopes and, 101–102 JScript.Net, 58, 159 ajax.loadFragment method, 94 JsLint, 474 pseudo code for, 94 JSON, support for, 175 Linux in Comet, 322 ECMAScript 5 and, 160 controllers, in Node.js, 347–350 Jar file on, 45 server connections and, 331, 333–334 JsTestDriver testing, 48 JsTestDriver, 43–52. See also Jar file load paths, 46–47 AJAX and, 249–250 local requests, 273–274 assertions, 51–52 success handler for, 273–274 browser capture for, 46 URLs and, 274 in browsers, 43 long polling, 315–320 command line productivity, 51 cache issues with, 319–320 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  16. 488 Index long polling (Continued ) setModel in, 413 feature tests for, 320 setView method and, 393, 414–416 implementation of, 316–319 subscription to, 412–414 low latency from, 316 user additions, 416 stubbing dates with, 316–319 user tracking in, 419 looping properties, 128–130 view settings, 414–416 ajax.cometClient, 327 XSS protection in, 418 Meszaros, Gerard, 440 M misbehaving observers, 233–234 manual stubbing, 257–258 exceptions, 234 memoization, 112–115 mixins, 157–158 argument serialization in, 114 definition of, 157 definition of, 112 Enumerable module and, 157–158 Fibonacci sequence in, 112–114 mocks, 453–458 general methods, 113–114 ajax.poll, 453 limiting of, 114 anonymous, 454 messageFormController, 424 automatic verification of, 454 message forms, 422–429 behavior verification with, 457, acquisition of, 428 470–472 in chat client model, 429 definition of, 453 for current users, 426–428 dependency silencing by, 457 empty function additions in, 426 method restoration of, 453–454 extraction of, 423 multiple expectations of, 455–456 feature tests for, 428–429 notify method and, 454 handleSubmit method and, 425 in POST requests, 284 message clearance in, 433 stubs v., 457–458 message form controllers and, 422 for tddjs.ajax.poller, 298–299 messageFormController with, 424 this value, 456 publishing of, 425–428 Model-View-Controller (MVC), 391 refactoring of, 423–425 Model-View-Presenter (MVP), 391 setModel moving in, 425 axis for, 391 TDD and, 428 components for, 391 test setup with, 422 passive view in, 391 userFormController with, 423–424 module patterns, 107 view setting with, 422–425 mouseover events, 184 messageListController, 412 Mozilla, 58 message lists, with DOM manipulation, MVC. See Model-View-Controller 411–421 MVP. See Model-View-Presenter addMessage with, 413–414 bootstrap scripts and, 421 N controller definition with, 411–412 named function expressions, 75 feature tests for, 420 in Internet Explorer, 86–87 initialization of, 420–421 namespace method, 187 message addition to, 416–418 namespaces, 103–107 messageListController, 412 for AJAX, 256, 290 model setting, 411–414 custom creation of, 106 node lists and, 419 definition of, 105–106 observe method with, 413 functions of, 104–105 reference storage with, 417 implementation of, 104–106 repeated messages in, 418–420 importing, 106–107 scrolling of, 432 in libraries, 104 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  17. Index 489 native, 103 circle, 152 objects as, 103–104 composition, 150–157 for XMLHttpRequest object, 251 from constructors, 130–132, 239–240 name tabbed panels, 182 direct inheritance in, 151 name tests, 462 ECMA-262, 118 native objects, 202–204 encapsulation of, 145–150 ECMAScript specification in, 202 in functional inheritance, 149–150 nested callbacks, 367 information hiding and, 145–150 new operators, 131–132 inspection of, 131 Node.js, 341–387. See also controllers; domain mixins, 157–158 models, for Node.js; promises, with new operators, 131–132 Node.js Object.create method, 151–153 access tokens in, 381–382, 385–386 object literals, 117–118 assertions for, 347 Object.prototype.hasOwnProperty, controllers with, 345–357, 378–386 125 directory structure for, 342–343 observable, 239–240 domain models, 358–366 private methods for, 145–147 environments for, setting up, 342–343 prototype chains, 119–122 event emitters, 372–378 prototypes, 130–135 events with, 342 radius property, 131 framework testing for, 343 sphere, 151–152 HTTP server, 344 in strict mode, 174 message filters, 381–382 tddjs.extend method, 153–157 nested callbacks and, 367 Object.create method, 151–153, 168–169 node-paperboy, 408–409 direct inheritance in, 151 promises with, 367–372 ECMAScript 5 and, 165–166, 167–168 respond method with, 382–383 for function creation, 169–170 runtime, 341–344 Function.prototype.inherit servers with, 343–344 function, 152–153 starting point for, 343–344 implementation of, 152, 165–166 startup scripts for, 344 inheritance models, 151 static files, 408–411 with properties, 165 storage for, 358–366 Object.defineProperty, 166 stubbing and, 452 object detection, in browser sniffing, test scripts for, 343 199–206 node lists, 419 addEventHandler method and, 206 node-paperboy, 408–409 event handling in, 201 notify method, 243–245 host objects and, 202–204 arguments for, 243 individual features of, 200 implementation of, 245 native objects and, 202–204 mocks and, 454 premise of, 200 relevant observers for, 243–244 purposes of, 200–206 storage of, 244–245 sample use testing in, 204–206 testing for, 244 strftime and, 204–206 updating of, 245 testing of, 201 type checking in, 201–202 O object literals, 117–118 object(s), 117–136, 150–157. See also arbitrary object model, ECMAScript 5 and, 161–171 objects; private methods, for objects Circle hybrid in, 168–169 arbitrary, 235–241 empowered properties, 162 arguments, 153 Enumerable module and, 161 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  18. 490 Index object model, ECMAScript 5 and (Continued ) refactoring with, 17, 225–226, 229–230 get function, 161 roles within, 219–220 getters in, 166–167 search results for, 220 name/value assignment in, 161–162 stubbing and, 445 Object.create method in, 165–168 testing, 222–225 Object.seal implementation in, 163 observers, with ajax.cometClient, property attributes, 161–163, 167–170 325–329 property descriptor changes in, 162 addition of, 327–329 prototypal inheritance in, 164–166 saving of, 328 reserved keywords in, 170–171 testing of, 328 set function, 161 type checking of, 329 setters in, 166–167 obsolete constructors, 236–238 shortcuts in, 164 addObserver method and, 237 writable, 161 array definition with, 238 Object.prototype, 75, 120–121 emptying of, 238 Object.prototype.hasOwnProperty, one-liners, 311–313 124–126 poller interfaces, 311 browsers in, 125 start method and, 312–313 loop qualification, 124 URLs and, 313 objects in, 125 onreadystatechangehandler, 263–268 Object.seal method, 163 AJAX and, 266–267 observable objects, 239–240 anonymous closure of, 267 with Comet, 321 assignment verification for, 264 observe method, 241–242 callbacks for, 266–268 call updating, 241–242 empty, 264 formal parameters for, 242 handling of, 265–268 message lists, 413 send method, 264–265 observer notification, 230–232 testing of, 265–268 calls, 230–231 open method, 259–260 passing arguments in, 231–232 OSX, JsTestDriver testing for, 48 observer pattern, 219–246. See also arbitrary outputs objects; bogus observers; error handling; in hard-coding, 27 observer notification in TDD, 24–25 adding constructors in, 223 adding observers to, 222–225 P addObserver method with, 224–230 passing arguments, 231–232 for arbitrary events, 241–246 test confirmation and, 231 for arbitrary objects, 235–241 performance tests, 60–69 arrays in, 224–225 benchmarks, 60–69 code writing for, 220 bottlenecks, 68–69 configuration files with, 221 closures, 60 definition of, 219 footprints for, 63 directory layouts in, 221 jQuery, 69 DOM events and, 220 relative performance of, 60–69 environment setting for, 221 setTimeout calls, 63 error handling in, 232–235 YUI, 63 in JavaScript, 220–221 Plug-ins, for JsTestDriver, 43 JsTestDriver and, 221 polling, for data, 294–313. See also Observable constructors with, 222 tddjs.ajax.poller observe method, 241–242 callbacks and, 308–311 observer notification, 230–232 directory layout in, 294 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  19. Index 491 in Facebook, 294 getMessageSince method final version of, 313 with, 372 in GTalk, 294 grouping of, 371–372 headers and, 308–311 nested callbacks, 367 jsTestDriver and, 295 rejection of, 369–370 load order with, 295 resolution of, 370–371 one-liners and, 311–313 resolve method with, 367 project layout in, 294–295 returning, 368–369 with server connections, 330, 334 test conversion with, 371 with tddjs.ajax.poller, then method with, 369 295–302 properties, prototypal inheritance and, timer testing, 303–308 117–130 post method, 378–380 access, 118–119 closing connections with, 379 attributes, 126–130 response times with, 380 DontDelete attribute for, 126 verification delay with, 379 DontEnum attribute for, 126–128 POST requests, 277–287 dot notation in, 118 assertions in, 283 ECMA-262 and, 126 configuration methods with, 278–279 enumerable, 122–126 copy-pasting for, 278 inheritance, 120–121 cropping, 280 looping, 128–130 data additions, 286–287 names, with spaces, 119 data handling functions in, 284–285 ReadOnly attribute for, 126 data transport for, 282–287 shadowing, 120–121 delegation to, 281 square bracket notation in, 118 encoding data in, 283–285 test methods for, 119 expectation of, 281 toString method and, 119 extraction of data in, 278, 285 values for, 120 GET requests and, 285–287 whitespace and, 118 implementation of, 277–281 property identifiers, reserved keywords and, introductions for, 281 170–171 method call changes for, 280 prototypal inheritance, 117–130, 136–144, 158. mocking in, 284 See also functional inheritance; _super Node.js messages, 347–354 method ReadyStateHandlerTest, 280 access in, 138–139 setting headers for, 287 Circle.prototype, 136–137 string encoding with, 282 ECMA-262 and, 138 stubbing in, 284 in ECMAScript 5, 164–166 in TDD, 279 functional, 148–150, 158 test cases for, 279–280 functions, 137–138 updating of, 280 implementation of, 138 URLs and, 282, 285 properties and, 117–130 private methods, for objects, 145–147 specifications for, 137 closures and, 145 Sphere.prototype, 136–137 definition of, 145–146 super, as concept, 139–144 function object creations in, 147 _super method, 140–143 inside constructors, 146–147 surface area calculations for, 139–140 promises, with Node.js, 367–372 prototype chains, 119–122 addMessage refactoring, 367–371 Array.prototype, 121–122 consumption of, 371–372 ECMA-262 specification in, 119 definition of, 367 inheritance models, 119–120 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
  20. 492 Index prototype chains, (Continued) function, 80, 82 object extension through, 121–122 global, 80, 101–102 Object.prototype, 120–121 scope chain, 83–84 Prototype.js library, 40 decrementing functions, 84 prototypes, 130–135 incrementing functions, 84 Circle.prototype, 132–134, 136–137, scrolling, 431–432 143 of message lists, 432 constructors, 130, 132 stubbing in, 432 property additions to, 132–135 send method onreadystatechangehandler and, Q 264–265 QUnit testing frameworks, 40 server connections, 329–338 callbacks with, 333 R concerns with, 334–338 radius property, 131 custom headers with, 336 in encapsulation, 148 data dispatching with, 332–334 ReadOnly attribute, 126 ECMAScript5 and, 333 ReadyStateHandlerTest, 280 exceptions to, 331 red, as symbol for failure in unit testing, 10 JSON data and, 331, 333–334 refactoring, 17, 225–226, 229–230 JsTestDriver and, 333 with addMessage, 367–371 missing URLs and, 331 with addObserver method, 225 obtaining of, 329 with AJAX, 292 polling for, 330, 334 arrays for, 226 request headers with, 337 duplicated test removal, 229–230 response data in, 332 hard-coding and, 225–226 tokens with, 336 of message forms, 423–425 Server Push, 293 method renaming and, 17 setModel additions, 402 in notify method, 245 with message forms, 425 with observer pattern, 17 with message lists, 413 TDD and, 28 setters, 166–167 test failure and, 17 setTimeout calls, 63 unit tests, 17 setTimout method, binding regression testing, 16 arguments, 97 renaming methods, 240–241 setUp function, xUnits and, 35 reserved keywords, 170–171 setUp method, 13–14 property identifiers and, 170–171 setView method, 393, 414–416 Resig, John, 42 compliant, 415 resolve method, 367 single responsibility principle, 30–31 respond method, 382–384, 386 sleep function, 35 dedicated, 383 slice function, 153 initial tests for, 382–384 sphere objects, 151–152 response codes, 355 Sphere.prototype, 136–137 Reverse Ajax, 314 Circle.prototype and, 138 Rhino, 42 functional inheritance and, 150 S implementation of, 143 saboteurs, 445 _super method, 143 scope, 80–84 testing for, 137 Ad Hoc, 101–103 spliced arrays, 57 blocking of, 80 square bracket notation, 118 chains in, 83–84 start method, 296–298 Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. From the Library of WoweBook.Com
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