unexpected

<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,user-scalable=0"> <link rel="stylesheet" href="/static/normalize.css" type="text/css" media="screen" /> <link rel="stylesheet" href="/static/main.css" type="text/css" media="screen" /> <link rel="shortcut icon" type="image/vnd.microsoft.icon" href="/static/bug-icon-black.ico"> <title>function - to throw</title> </head> <body class="sidebar-hidden has-sidebar"> <header> <div class="logo-icon"></div> <nav> <ul> <li class="menu-toggle-item"> <button class="menu-toggle" onclick="toggleSidebar()"></button> </li> <li class=""><a href="/">Unexpected</a></li> <li class="active"><a href="/assertions/any/to-be-a/">Assertions</a></li> <li class=""><a href="/api/addAssertion/">API</a></li> </ul> </nav> <div class="search" style="visibility: hidden"> <input id="search" placeholder="Search..." value=""> <div id="searchDropDown" class="dropDown"> <ul id="searchResults"></ul> </div> </div> </header> <section id="assertions"> <nav id="assertion-menu" class="sidebar js-remember-scroll-position"> <ul> <li> <h3>any</h3> <ul> <li class=""> <a href="/assertions/any/to-be-a/">to be a</a> </li> <li class=""> <a href="/assertions/any/to-be-falsy/">to be falsy</a> </li> <li class=""> <a href="/assertions/any/to-be-null/">to be null</a> </li> <li class=""> <a href="/assertions/any/to-be-ok/">to be ok</a> </li> <li class=""> <a href="/assertions/any/to-be-truthy/">to be truthy</a> </li> <li class=""> <a href="/assertions/any/to-be-undefined/">to be undefined</a> </li> <li class=""> <a href="/assertions/any/to-be/">to be</a> </li> <li class=""> <a href="/assertions/any/to-equal/">to equal</a> </li> <li class=""> <a href="/assertions/any/to-satisfy/">to satisfy</a> </li> <li class=""> <a href="/assertions/any/to-be-defined/">to be defined</a> </li> </ul> </li> <li> <h3>array</h3> <ul> <li class=""> <a href="/assertions/array/to-be-an-array-whose-items-satisfy/">to be an array whose items satisfy</a> </li> <li class=""> <a href="/assertions/array/to-be-empty/">to be empty</a> </li> <li class=""> <a href="/assertions/array/to-be-non-empty/">to be non-empty</a> </li> <li class=""> <a href="/assertions/array/to-contain/">to contain</a> </li> <li class=""> <a href="/assertions/array/to-have-length/">to have length</a> </li> </ul> </li> <li> <h3>boolean</h3> <ul> <li class=""> <a href="/assertions/boolean/to-be-false/">to be false</a> </li> <li class=""> <a href="/assertions/boolean/to-be-true/">to be true</a> </li> </ul> </li> <li> <h3>function</h3> <ul> <li class=""> <a href="/assertions/function/to-have-arity/">to have arity</a> </li> <li class="active"> <a href="/assertions/function/to-throw/">to throw</a> </li> </ul> </li> <li> <h3>number</h3> <ul> <li class=""> <a href="/assertions/number/to-be-greater-than/">to be greater than</a> </li> <li class=""> <a href="/assertions/number/to-be-infinite/">to be infinite</a> </li> <li class=""> <a href="/assertions/number/to-be-close-to/">to be close to</a> </li> <li class=""> <a href="/assertions/number/to-be-finite/">to be finite</a> </li> <li class=""> <a href="/assertions/number/to-be-greater-than-or-equal-to/">to be greater than or equal to</a> </li> <li class=""> <a href="/assertions/number/to-be-NaN/">to be NaN</a> </li> <li class=""> <a href="/assertions/number/to-be-less-than-or-equal-to/">to be less than or equal to</a> </li> <li class=""> <a href="/assertions/number/to-be-less-than/">to be less than</a> </li> <li class=""> <a href="/assertions/number/to-be-negative/">to be negative</a> </li> <li class=""> <a href="/assertions/number/to-be-positive/">to be positive</a> </li> <li class=""> <a href="/assertions/number/to-be-within/">to be within</a> </li> </ul> </li> <li> <h3>object</h3> <ul> <li class=""> <a href="/assertions/object/to-be-a-map-whose-keys-satisfy/">to be a map whose keys satisfy</a> </li> <li class=""> <a href="/assertions/object/to-be-a-map-whose-values-satisfy/">to be a map whose values satisfy</a> </li> <li class=""> <a href="/assertions/object/to-be-canonical/">to be canonical</a> </li> <li class=""> <a href="/assertions/object/to-have-key/">to have key</a> </li> <li class=""> <a href="/assertions/object/to-have-keys/">to have keys</a> </li> <li class=""> <a href="/assertions/object/to-have-properties/">to have properties</a> </li> <li class=""> <a href="/assertions/object/to-have-property/">to have property</a> </li> </ul> </li> <li> <h3>string</h3> <ul> <li class=""> <a href="/assertions/string/to-be-non-empty/">to be non-empty</a> </li> <li class=""> <a href="/assertions/string/to-be-empty/">to be empty</a> </li> <li class=""> <a href="/assertions/string/to-be-greater-than/">to be greater than</a> </li> <li class=""> <a href="/assertions/string/to-be-less-than-or-equal-to/">to be less than or equal to</a> </li> <li class=""> <a href="/assertions/string/to-be-less-than/">to be less than</a> </li> <li class=""> <a href="/assertions/string/to-be-greater-than-or-equal-to/">to be greater than or equal to</a> </li> <li class=""> <a href="/assertions/string/to-be-within/">to be within</a> </li> <li class=""> <a href="/assertions/string/to-be/">to be</a> </li> <li class=""> <a href="/assertions/string/to-contain/">to contain</a> </li> <li class=""> <a href="/assertions/string/to-have-length/">to have length</a> </li> <li class=""> <a href="/assertions/string/to-match/">to match</a> </li> </ul> </li> </ul> </nav> <div class="main"> <div class="content"> <p>Asserts that the function throws an error when called.</p> <div class="code lang-javascript"> <div><span style="color: #a71d5d">function</span> <span style="color: #000000">willThrow</span><span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The error message'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">}</span></div> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span>willThrow<span style="color: #000000">,</span> <span style="color: #df5000">'to throw'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span>willThrow<span style="color: #000000">,</span> <span style="color: #df5000">'to throw error'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span>willThrow<span style="color: #000000">,</span> <span style="color: #df5000">'to throw exception'</span><span style="color: #000000">);</span></div> </div><p>In case of a failing expectation you get the following output:</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">willNotThrow</span><span style="color: #000000">()</span> <span style="color: #000000">{},</span> <span style="color: #df5000">'to throw'</span><span style="color: #000000">);</span></div> </div><div class="output"> <div><span style="color: red; font-weight: bold">expected</span> <span style="color: #a71d5d">function</span> <span style="color: #000000">willNotThrow</span><span style="color: #000000">()</span> <span style="color: #000000">{}</span> <span style="color: red; font-weight: bold">to throw</span></div> </div><p>You can assert the error message is a given string if you provide a string as the second parameter.</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The error message'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'to throw'</span><span style="color: #000000">,</span> <span style="color: #df5000">'The error message'</span><span style="color: #000000">);</span></div> </div><p>In case of a failing expectation you get the following output:</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The error message!'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'to throw'</span><span style="color: #000000">,</span> <span style="color: #df5000">'The error message'</span><span style="color: #000000">);</span></div> </div><div class="output"> <div><span style="color: red; font-weight: bold">expected</span></div> <div><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The error message!'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">}</span></div> <div><span style="color: red; font-weight: bold">to throw</span> <span style="color: #df5000">'The error message'</span></div> <div>  <div style="display: inline-block; vertical-align: top"> <div><span style="color: red; font-weight: bold">expected</span> Error({ <span style="color: #555">message</span>: <span style="color: #df5000">'The error message!'</span> }) <span style="color: red; font-weight: bold">to satisfy</span> <span style="color: #df5000">'The error message'</span></div> <div> </div> <div><div style="display: inline-block; vertical-align: top"> <div><span style="color: red">-</span></div> </div><div style="display: inline-block; vertical-align: top"> <div><span style="color: red">The error message</span><span style="background-color: red; color: white">!</span></div> </div></div> <div><div style="display: inline-block; vertical-align: top"> <div><span style="color: green">+</span></div> </div><div style="display: inline-block; vertical-align: top"> <div><span style="color: green">The error message</span></div> </div></div> </div></div> </div><p>By providing a regular expression as the second parameter you can assert the error message matches the given regular expression.</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The error message'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'to throw'</span><span style="color: #000000">,</span> <span style="color: #183691">/error message/</span><span style="color: #000000">);</span></div> </div><p>In case of a failing expectation you get the following output:</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The error message!'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'to throw'</span><span style="color: #000000">,</span> <span style="color: #183691">/catastrophic failure/</span><span style="color: #000000">);</span></div> </div><div class="output"> <div><span style="color: red; font-weight: bold">expected</span></div> <div><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The error message!'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">}</span></div> <div><span style="color: red; font-weight: bold">to throw</span> <span style="color: #183691">/catastrophic failure/</span></div> <div>  <div style="display: inline-block; vertical-align: top"> <div><span style="color: red; font-weight: bold">expected</span> Error({ <span style="color: #555">message</span>: <span style="color: #df5000">'The error message!'</span> }) <span style="color: red; font-weight: bold">to satisfy</span> <span style="color: #183691">/catastrophic failure/</span></div> </div></div> </div><p>You can also provide a function as the second parameter to do arbitrary assertions on the error.</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">this</span><span style="color: #000000">.</span>foo<span style="color: #000000">.</span><span style="color: #000000">bar</span><span style="color: #000000">();</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'to throw'</span><span style="color: #000000">,</span> <span style="color: #a71d5d">function</span> <span style="color: #000000">(</span>e<span style="color: #000000">)</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #000000">expect</span><span style="color: #000000">(</span>e<span style="color: #000000">,</span> <span style="color: #df5000">'to be a'</span><span style="color: #000000">,</span> TypeError<span style="color: #000000">);</span></div> <div><span style="color: #000000">});</span></div> </div><p>In case of a failing expectation you get the following output:</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'Another error'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'to throw'</span><span style="color: #000000">,</span> <span style="color: #a71d5d">function</span> <span style="color: #000000">(</span>e<span style="color: #000000">)</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #000000">expect</span><span style="color: #000000">(</span>e<span style="color: #000000">,</span> <span style="color: #df5000">'to be a'</span><span style="color: #000000">,</span> TypeError<span style="color: #000000">);</span></div> <div><span style="color: #000000">});</span></div> </div><div class="output"> <div><span style="color: red; font-weight: bold">expected</span></div> <div><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'Another error'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">}</span></div> <div><span style="color: red; font-weight: bold">to throw</span></div> <div><span style="color: #a71d5d">function</span> <span style="color: #000000">(</span>e<span style="color: #000000">)</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #000000">expect</span><span style="color: #000000">(</span>e<span style="color: #000000">,</span> <span style="color: #df5000">'to be a'</span><span style="color: #000000">,</span> TypeError<span style="color: #000000">);</span></div> <div><span style="color: #000000">}</span></div> <div>  <div style="display: inline-block; vertical-align: top"> <div><span style="color: red; font-weight: bold">expected</span> Error({ <span style="color: #555">message</span>: <span style="color: #df5000">'Another error'</span> }) <span style="color: red; font-weight: bold">to be a</span> TypeError</div> </div></div> </div><p>This assertion can be negated using the <code>not</code> flag:</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div> <span style="color: #969896"> // Do some work that should not throw</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'not to throw'</span><span style="color: #000000">);</span></div> </div><p>In case of a failing expectation you get the following output:</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'threw anyway'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'not to throw'</span><span style="color: #000000">);</span></div> </div><div class="output"> <div><span style="color: red; font-weight: bold">expected</span></div> <div><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'threw anyway'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">}</span></div> <div><span style="color: red; font-weight: bold">not to throw</span></div> <div>  <div style="display: inline-block; vertical-align: top"> <div><span style="color: red; font-weight: bold">threw: </span>Error({ <span style="color: #555">message</span>: <span style="color: #df5000">'threw anyway'</span> })</div> </div></div> </div><p>You can also use the <code>not</code> flag in combination with matching the error message.</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The correct error message'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'not to throw'</span><span style="color: #000000">,</span> <span style="color: #183691">/great success/</span><span style="color: #000000">);</span></div> </div><p>In case of a failing expectation you get the following output:</p> <div class="code lang-javascript"> <div><span style="color: #000000">expect</span><span style="color: #000000">(</span><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The correct error message'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">},</span> <span style="color: #df5000">'not to throw'</span><span style="color: #000000">,</span> <span style="color: #183691">/error/</span><span style="color: #000000">);</span></div> </div><div class="output"> <div><span style="color: red; font-weight: bold">expected</span></div> <div><span style="color: #a71d5d">function</span> <span style="color: #000000">()</span> <span style="color: #000000">{</span></div> <div>  <span style="color: #a71d5d">throw</span> <span style="color: #a71d5d">new</span> Error<span style="color: #000000">(</span><span style="color: #df5000">'The correct error message'</span><span style="color: #000000">);</span></div> <div><span style="color: #000000">}</span></div> <div><span style="color: red; font-weight: bold">not to throw</span> <span style="color: #183691">/error/</span></div> <div>  <div style="display: inline-block; vertical-align: top"> <div><span style="color: red; font-weight: bold">expected</span> Error({ <span style="color: #555">message</span>: <span style="color: #df5000">'The correct error message'</span> }) <span style="color: red; font-weight: bold">not to satisfy</span> <span style="color: #183691">/error/</span></div> </div></div> </div> </div> </div> </section> <script type="text/javascript" src="/static/toggleSidebar.js"></script> <script type="text/javascript" src="/static/rememberScrollPosition.js"></script> <script type="text/javascript" src="/static/search.js"></script> </body> </html>