540 lines
38 KiB
HTML
540 lines
38 KiB
HTML
<!DOCTYPE HTML>
|
||
<html lang="en" class="light sidebar-visible" dir="ltr">
|
||
<head>
|
||
<!-- Book generated using mdBook -->
|
||
<meta charset="UTF-8">
|
||
<title>Test Organization - The Rust Programming Language</title>
|
||
|
||
|
||
<!-- Custom HTML head -->
|
||
|
||
<meta name="description" content="">
|
||
<meta name="viewport" content="width=device-width, initial-scale=1">
|
||
<meta name="theme-color" content="#ffffff">
|
||
|
||
<link rel="icon" href="favicon-de23e50b.svg">
|
||
<link rel="shortcut icon" href="favicon-8114d1fc.png">
|
||
<link rel="stylesheet" href="css/variables-8adf115d.css">
|
||
<link rel="stylesheet" href="css/general-0392ca55.css">
|
||
<link rel="stylesheet" href="css/chrome-fc474251.css">
|
||
<link rel="stylesheet" href="css/print-9e4910d8.css" media="print">
|
||
|
||
<!-- Fonts -->
|
||
<link rel="stylesheet" href="fonts/fonts-9644e21d.css">
|
||
|
||
<!-- Highlight.js Stylesheets -->
|
||
<link rel="stylesheet" id="mdbook-highlight-css" href="highlight-493f70e1.css">
|
||
<link rel="stylesheet" id="mdbook-tomorrow-night-css" href="tomorrow-night-4c0ae647.css">
|
||
<link rel="stylesheet" id="mdbook-ayu-highlight-css" href="ayu-highlight-3fdfc3ac.css">
|
||
|
||
<!-- Custom theme stylesheets -->
|
||
<link rel="stylesheet" href="ferris-d33b75bf.css">
|
||
<link rel="stylesheet" href="theme/2018-edition-4e126c62.css">
|
||
<link rel="stylesheet" href="theme/semantic-notes-9b5766c0.css">
|
||
<link rel="stylesheet" href="theme/listing-cab26221.css">
|
||
|
||
|
||
<!-- Provide site root and default themes to javascript -->
|
||
<script>
|
||
const path_to_root = "";
|
||
const default_light_theme = "light";
|
||
const default_dark_theme = "navy";
|
||
window.path_to_searchindex_js = "searchindex-6a1da8cc.js";
|
||
</script>
|
||
<!-- Start loading toc.js asap -->
|
||
<script src="toc-0e4ce700.js"></script>
|
||
</head>
|
||
<body>
|
||
<div id="mdbook-help-container">
|
||
<div id="mdbook-help-popup">
|
||
<h2 class="mdbook-help-title">Keyboard shortcuts</h2>
|
||
<div>
|
||
<p>Press <kbd>←</kbd> or <kbd>→</kbd> to navigate between chapters</p>
|
||
<p>Press <kbd>S</kbd> or <kbd>/</kbd> to search in the book</p>
|
||
<p>Press <kbd>?</kbd> to show this help</p>
|
||
<p>Press <kbd>Esc</kbd> to hide this help</p>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<div id="mdbook-body-container">
|
||
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
||
<script>
|
||
try {
|
||
let theme = localStorage.getItem('mdbook-theme');
|
||
let sidebar = localStorage.getItem('mdbook-sidebar');
|
||
|
||
if (theme.startsWith('"') && theme.endsWith('"')) {
|
||
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
||
}
|
||
|
||
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
||
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
||
}
|
||
} catch (e) { }
|
||
</script>
|
||
|
||
<!-- Set the theme before any content is loaded, prevents flash -->
|
||
<script>
|
||
const default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? default_dark_theme : default_light_theme;
|
||
let theme;
|
||
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
||
if (theme === null || theme === undefined) { theme = default_theme; }
|
||
const html = document.documentElement;
|
||
html.classList.remove('light')
|
||
html.classList.add(theme);
|
||
html.classList.add("js");
|
||
</script>
|
||
|
||
<input type="checkbox" id="mdbook-sidebar-toggle-anchor" class="hidden">
|
||
|
||
<!-- Hide / unhide sidebar before it is displayed -->
|
||
<script>
|
||
let sidebar = null;
|
||
const sidebar_toggle = document.getElementById("mdbook-sidebar-toggle-anchor");
|
||
if (document.body.clientWidth >= 1080) {
|
||
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
||
sidebar = sidebar || 'visible';
|
||
} else {
|
||
sidebar = 'hidden';
|
||
sidebar_toggle.checked = false;
|
||
}
|
||
if (sidebar === 'visible') {
|
||
sidebar_toggle.checked = true;
|
||
} else {
|
||
html.classList.remove('sidebar-visible');
|
||
}
|
||
</script>
|
||
|
||
<nav id="mdbook-sidebar" class="sidebar" aria-label="Table of contents">
|
||
<!-- populated by js -->
|
||
<mdbook-sidebar-scrollbox class="sidebar-scrollbox"></mdbook-sidebar-scrollbox>
|
||
<noscript>
|
||
<iframe class="sidebar-iframe-outer" src="toc.html"></iframe>
|
||
</noscript>
|
||
<div id="mdbook-sidebar-resize-handle" class="sidebar-resize-handle">
|
||
<div class="sidebar-resize-indicator"></div>
|
||
</div>
|
||
</nav>
|
||
|
||
<div id="mdbook-page-wrapper" class="page-wrapper">
|
||
|
||
<div class="page">
|
||
<div id="mdbook-menu-bar-hover-placeholder"></div>
|
||
<div id="mdbook-menu-bar" class="menu-bar sticky">
|
||
<div class="left-buttons">
|
||
<label id="mdbook-sidebar-toggle" class="icon-button" for="mdbook-sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="mdbook-sidebar">
|
||
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M0 96C0 78.3 14.3 64 32 64H416c17.7 0 32 14.3 32 32s-14.3 32-32 32H32C14.3 128 0 113.7 0 96zM0 256c0-17.7 14.3-32 32-32H416c17.7 0 32 14.3 32 32s-14.3 32-32 32H32c-17.7 0-32-14.3-32-32zM448 416c0 17.7-14.3 32-32 32H32c-17.7 0-32-14.3-32-32s14.3-32 32-32H416c17.7 0 32 14.3 32 32z"/></svg></span>
|
||
</label>
|
||
<button id="mdbook-theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="mdbook-theme-list">
|
||
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 576 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M371.3 367.1c27.3-3.9 51.9-19.4 67.2-42.9L600.2 74.1c12.6-19.5 9.4-45.3-7.6-61.2S549.7-4.4 531.1 9.6L294.4 187.2c-24 18-38.2 46.1-38.4 76.1L371.3 367.1zm-19.6 25.4l-116-104.4C175.9 290.3 128 339.6 128 400c0 3.9 .2 7.8 .6 11.6c1.8 17.5-10.2 36.4-27.8 36.4H96c-17.7 0-32 14.3-32 32s14.3 32 32 32H240c61.9 0 112-50.1 112-112c0-2.5-.1-5-.2-7.5z"/></svg></span>
|
||
</button>
|
||
<ul id="mdbook-theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
||
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-default_theme">Auto</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-light">Light</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-rust">Rust</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-coal">Coal</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-navy">Navy</button></li>
|
||
<li role="none"><button role="menuitem" class="theme" id="mdbook-theme-ayu">Ayu</button></li>
|
||
</ul>
|
||
<button id="mdbook-search-toggle" class="icon-button" type="button" title="Search (`/`)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="/ s" aria-controls="mdbook-searchbar">
|
||
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M416 208c0 45.9-14.9 88.3-40 122.7L502.6 457.4c12.5 12.5 12.5 32.8 0 45.3s-32.8 12.5-45.3 0L330.7 376c-34.4 25.2-76.8 40-122.7 40C93.1 416 0 322.9 0 208S93.1 0 208 0S416 93.1 416 208zM208 352c79.5 0 144-64.5 144-144s-64.5-144-144-144S64 128.5 64 208s64.5 144 144 144z"/></svg></span>
|
||
</button>
|
||
</div>
|
||
|
||
<h1 class="menu-title">The Rust Programming Language</h1>
|
||
|
||
<div class="right-buttons">
|
||
<a href="print.html" title="Print this book" aria-label="Print this book">
|
||
<span class=fa-svg id="print-button"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M128 0C92.7 0 64 28.7 64 64v96h64V64H354.7L384 93.3V160h64V93.3c0-17-6.7-33.3-18.7-45.3L400 18.7C388 6.7 371.7 0 354.7 0H128zM384 352v32 64H128V384 368 352H384zm64 32h32c17.7 0 32-14.3 32-32V256c0-35.3-28.7-64-64-64H64c-35.3 0-64 28.7-64 64v96c0 17.7 14.3 32 32 32H64v64c0 35.3 28.7 64 64 64H384c35.3 0 64-28.7 64-64V384zm-16-88c-13.3 0-24-10.7-24-24s10.7-24 24-24s24 10.7 24 24s-10.7 24-24 24z"/></svg></span>
|
||
</a>
|
||
<a href="https://github.com/rust-lang/book" title="Git repository" aria-label="Git repository">
|
||
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 496 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M165.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6zm-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3zm44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9zM244.8 8C106.1 8 0 113.3 0 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C428.2 457.8 496 362.9 496 252 496 113.3 383.5 8 244.8 8zM97.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1zm-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7zm32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1zm-11.4-14.7c-1.6 1-1.6 3.6 0 5.9 1.6 2.3 4.3 3.3 5.6 2.3 1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2z"/></svg></span>
|
||
</a>
|
||
|
||
</div>
|
||
</div>
|
||
|
||
<div id="mdbook-search-wrapper" class="hidden">
|
||
<form id="mdbook-searchbar-outer" class="searchbar-outer">
|
||
<div class="search-wrapper">
|
||
<input type="search" id="mdbook-searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="mdbook-searchresults-outer" aria-describedby="searchresults-header">
|
||
<div class="spinner-wrapper">
|
||
<span class=fa-svg id="fa-spin"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M304 48c0-26.5-21.5-48-48-48s-48 21.5-48 48s21.5 48 48 48s48-21.5 48-48zm0 416c0-26.5-21.5-48-48-48s-48 21.5-48 48s21.5 48 48 48s48-21.5 48-48zM48 304c26.5 0 48-21.5 48-48s-21.5-48-48-48s-48 21.5-48 48s21.5 48 48 48zm464-48c0-26.5-21.5-48-48-48s-48 21.5-48 48s21.5 48 48 48s48-21.5 48-48zM142.9 437c18.7-18.7 18.7-49.1 0-67.9s-49.1-18.7-67.9 0s-18.7 49.1 0 67.9s49.1 18.7 67.9 0zm0-294.2c18.7-18.7 18.7-49.1 0-67.9S93.7 56.2 75 75s-18.7 49.1 0 67.9s49.1 18.7 67.9 0zM369.1 437c18.7 18.7 49.1 18.7 67.9 0s18.7-49.1 0-67.9s-49.1-18.7-67.9 0s-18.7 49.1 0 67.9z"/></svg></span>
|
||
</div>
|
||
</div>
|
||
</form>
|
||
<div id="mdbook-searchresults-outer" class="searchresults-outer hidden">
|
||
<div id="mdbook-searchresults-header" class="searchresults-header"></div>
|
||
<ul id="mdbook-searchresults">
|
||
</ul>
|
||
</div>
|
||
</div>
|
||
|
||
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
||
<script>
|
||
document.getElementById('mdbook-sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
||
document.getElementById('mdbook-sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
||
Array.from(document.querySelectorAll('#mdbook-sidebar a')).forEach(function(link) {
|
||
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
||
});
|
||
</script>
|
||
|
||
<div id="mdbook-content" class="content">
|
||
<main>
|
||
<h2 id="test-organization"><a class="header" href="#test-organization">Test Organization</a></h2>
|
||
<p>As mentioned at the start of the chapter, testing is a complex discipline, and
|
||
different people use different terminology and organization. The Rust community
|
||
thinks about tests in terms of two main categories: unit tests and integration
|
||
tests. <em>Unit tests</em> are small and more focused, testing one module in isolation
|
||
at a time, and can test private interfaces. <em>Integration tests</em> are entirely
|
||
external to your library and use your code in the same way any other external
|
||
code would, using only the public interface and potentially exercising multiple
|
||
modules per test.</p>
|
||
<p>Writing both kinds of tests is important to ensure that the pieces of your
|
||
library are doing what you expect them to, separately and together.</p>
|
||
<h3 id="unit-tests"><a class="header" href="#unit-tests">Unit Tests</a></h3>
|
||
<p>The purpose of unit tests is to test each unit of code in isolation from the
|
||
rest of the code to quickly pinpoint where code is and isn’t working as
|
||
expected. You’ll put unit tests in the <em>src</em> directory in each file with the
|
||
code that they’re testing. The convention is to create a module named <code>tests</code>
|
||
in each file to contain the test functions and to annotate the module with
|
||
<code>cfg(test)</code>.</p>
|
||
<h4 id="the-tests-module-and-cfgtest"><a class="header" href="#the-tests-module-and-cfgtest">The <code>tests</code> Module and <code>#[cfg(test)]</code></a></h4>
|
||
<p>The <code>#[cfg(test)]</code> annotation on the <code>tests</code> module tells Rust to compile and
|
||
run the test code only when you run <code>cargo test</code>, not when you run <code>cargo build</code>. This saves compile time when you only want to build the library and
|
||
saves space in the resultant compiled artifact because the tests are not
|
||
included. You’ll see that because integration tests go in a different
|
||
directory, they don’t need the <code>#[cfg(test)]</code> annotation. However, because unit
|
||
tests go in the same files as the code, you’ll use <code>#[cfg(test)]</code> to specify
|
||
that they shouldn’t be included in the compiled result.</p>
|
||
<p>Recall that when we generated the new <code>adder</code> project in the first section of
|
||
this chapter, Cargo generated this code for us:</p>
|
||
<p><span class="filename">Filename: src/lib.rs</span></p>
|
||
<pre><code class="language-rust noplayground">pub fn add(left: u64, right: u64) -> u64 {
|
||
left + right
|
||
}
|
||
|
||
#[cfg(test)]
|
||
mod tests {
|
||
use super::*;
|
||
|
||
#[test]
|
||
fn it_works() {
|
||
let result = add(2, 2);
|
||
assert_eq!(result, 4);
|
||
}
|
||
}</code></pre>
|
||
<p>On the automatically generated <code>tests</code> module, the attribute <code>cfg</code> stands for
|
||
<em>configuration</em> and tells Rust that the following item should only be included
|
||
given a certain configuration option. In this case, the configuration option is
|
||
<code>test</code>, which is provided by Rust for compiling and running tests. By using the
|
||
<code>cfg</code> attribute, Cargo compiles our test code only if we actively run the tests
|
||
with <code>cargo test</code>. This includes any helper functions that might be within this
|
||
module, in addition to the functions annotated with <code>#[test]</code>.</p>
|
||
<!-- Old headings. Do not remove or links may break. -->
|
||
<p><a id="testing-private-functions"></a></p>
|
||
<h4 id="private-function-tests"><a class="header" href="#private-function-tests">Private Function Tests</a></h4>
|
||
<p>There’s debate within the testing community about whether or not private
|
||
functions should be tested directly, and other languages make it difficult or
|
||
impossible to test private functions. Regardless of which testing ideology you
|
||
adhere to, Rust’s privacy rules do allow you to test private functions.
|
||
Consider the code in Listing 11-12 with the private function <code>internal_adder</code>.</p>
|
||
<figure class="listing" id="listing-11-12">
|
||
<span class="file-name">Filename: src/lib.rs</span>
|
||
<pre><code class="language-rust noplayground">pub fn add_two(a: u64) -> u64 {
|
||
internal_adder(a, 2)
|
||
}
|
||
|
||
fn internal_adder(left: u64, right: u64) -> u64 {
|
||
left + right
|
||
}
|
||
|
||
#[cfg(test)]
|
||
mod tests {
|
||
use super::*;
|
||
|
||
#[test]
|
||
fn internal() {
|
||
let result = internal_adder(2, 2);
|
||
assert_eq!(result, 4);
|
||
}
|
||
}</code></pre>
|
||
<figcaption><a href="#listing-11-12">Listing 11-12</a>: Testing a private function</figcaption>
|
||
</figure>
|
||
<p>Note that the <code>internal_adder</code> function is not marked as <code>pub</code>. Tests are just
|
||
Rust code, and the <code>tests</code> module is just another module. As we discussed in
|
||
<a href="ch07-03-paths-for-referring-to-an-item-in-the-module-tree.html">“Paths for Referring to an Item in the Module Tree”</a><!-- ignore -->,
|
||
items in child modules can use the items in their ancestor modules. In this
|
||
test, we bring all of the items belonging to the <code>tests</code> module’s parent into
|
||
scope with <code>use super::*</code>, and then the test can call <code>internal_adder</code>. If you
|
||
don’t think private functions should be tested, there’s nothing in Rust that
|
||
will compel you to do so.</p>
|
||
<h3 id="integration-tests"><a class="header" href="#integration-tests">Integration Tests</a></h3>
|
||
<p>In Rust, integration tests are entirely external to your library. They use your
|
||
library in the same way any other code would, which means they can only call
|
||
functions that are part of your library’s public API. Their purpose is to test
|
||
whether many parts of your library work together correctly. Units of code that
|
||
work correctly on their own could have problems when integrated, so test
|
||
coverage of the integrated code is important as well. To create integration
|
||
tests, you first need a <em>tests</em> directory.</p>
|
||
<h4 id="the-tests-directory"><a class="header" href="#the-tests-directory">The <em>tests</em> Directory</a></h4>
|
||
<p>We create a <em>tests</em> directory at the top level of our project directory, next
|
||
to <em>src</em>. Cargo knows to look for integration test files in this directory. We
|
||
can then make as many test files as we want, and Cargo will compile each of the
|
||
files as an individual crate.</p>
|
||
<p>Let’s create an integration test. With the code in Listing 11-12 still in the
|
||
<em>src/lib.rs</em> file, make a <em>tests</em> directory, and create a new file named
|
||
<em>tests/integration_test.rs</em>. Your directory structure should look like this:</p>
|
||
<pre><code class="language-text">adder
|
||
├── Cargo.lock
|
||
├── Cargo.toml
|
||
├── src
|
||
│ └── lib.rs
|
||
└── tests
|
||
└── integration_test.rs
|
||
</code></pre>
|
||
<p>Enter the code in Listing 11-13 into the <em>tests/integration_test.rs</em> file.</p>
|
||
<figure class="listing" id="listing-11-13">
|
||
<span class="file-name">Filename: tests/integration_test.rs</span>
|
||
<pre><code class="language-rust ignore">use adder::add_two;
|
||
|
||
#[test]
|
||
fn it_adds_two() {
|
||
let result = add_two(2);
|
||
assert_eq!(result, 4);
|
||
}</code></pre>
|
||
<figcaption><a href="#listing-11-13">Listing 11-13</a>: An integration test of a function in the <code>adder</code> crate</figcaption>
|
||
</figure>
|
||
<p>Each file in the <em>tests</em> directory is a separate crate, so we need to bring our
|
||
library into each test crate’s scope. For that reason, we add <code>use adder::add_two;</code> at the top of the code, which we didn’t need in the unit tests.</p>
|
||
<p>We don’t need to annotate any code in <em>tests/integration_test.rs</em> with
|
||
<code>#[cfg(test)]</code>. Cargo treats the <em>tests</em> directory specially and compiles files
|
||
in this directory only when we run <code>cargo test</code>. Run <code>cargo test</code> now:</p>
|
||
<pre><code class="language-console">$ cargo test
|
||
Compiling adder v0.1.0 (file:///projects/adder)
|
||
Finished `test` profile [unoptimized + debuginfo] target(s) in 1.31s
|
||
Running unittests src/lib.rs (target/debug/deps/adder-1082c4b063a8fbe6)
|
||
|
||
running 1 test
|
||
test tests::internal ... ok
|
||
|
||
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
|
||
|
||
Running tests/integration_test.rs (target/debug/deps/integration_test-1082c4b063a8fbe6)
|
||
|
||
running 1 test
|
||
test it_adds_two ... ok
|
||
|
||
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
|
||
|
||
Doc-tests adder
|
||
|
||
running 0 tests
|
||
|
||
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
|
||
|
||
</code></pre>
|
||
<p>The three sections of output include the unit tests, the integration test, and
|
||
the doc tests. Note that if any test in a section fails, the following sections
|
||
will not be run. For example, if a unit test fails, there won’t be any output
|
||
for integration and doc tests, because those tests will only be run if all unit
|
||
tests are passing.</p>
|
||
<p>The first section for the unit tests is the same as we’ve been seeing: one line
|
||
for each unit test (one named <code>internal</code> that we added in Listing 11-12) and
|
||
then a summary line for the unit tests.</p>
|
||
<p>The integration tests section starts with the line <code>Running tests/integration_test.rs</code>. Next, there is a line for each test function in
|
||
that integration test and a summary line for the results of the integration
|
||
test just before the <code>Doc-tests adder</code> section starts.</p>
|
||
<p>Each integration test file has its own section, so if we add more files in the
|
||
<em>tests</em> directory, there will be more integration test sections.</p>
|
||
<p>We can still run a particular integration test function by specifying the test
|
||
function’s name as an argument to <code>cargo test</code>. To run all the tests in a
|
||
particular integration test file, use the <code>--test</code> argument of <code>cargo test</code>
|
||
followed by the name of the file:</p>
|
||
<pre><code class="language-console">$ cargo test --test integration_test
|
||
Compiling adder v0.1.0 (file:///projects/adder)
|
||
Finished `test` profile [unoptimized + debuginfo] target(s) in 0.64s
|
||
Running tests/integration_test.rs (target/debug/deps/integration_test-82e7799c1bc62298)
|
||
|
||
running 1 test
|
||
test it_adds_two ... ok
|
||
|
||
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
|
||
|
||
</code></pre>
|
||
<p>This command runs only the tests in the <em>tests/integration_test.rs</em> file.</p>
|
||
<h4 id="submodules-in-integration-tests"><a class="header" href="#submodules-in-integration-tests">Submodules in Integration Tests</a></h4>
|
||
<p>As you add more integration tests, you might want to make more files in the
|
||
<em>tests</em> directory to help organize them; for example, you can group the test
|
||
functions by the functionality they’re testing. As mentioned earlier, each file
|
||
in the <em>tests</em> directory is compiled as its own separate crate, which is useful
|
||
for creating separate scopes to more closely imitate the way end users will be
|
||
using your crate. However, this means files in the <em>tests</em> directory don’t
|
||
share the same behavior as files in <em>src</em> do, as you learned in Chapter 7
|
||
regarding how to separate code into modules and files.</p>
|
||
<p>The different behavior of <em>tests</em> directory files is most noticeable when you
|
||
have a set of helper functions to use in multiple integration test files, and
|
||
you try to follow the steps in the <a href="ch07-05-separating-modules-into-different-files.html">“Separating Modules into Different
|
||
Files”</a><!-- ignore --> section of Chapter 7 to
|
||
extract them into a common module. For example, if we create <em>tests/common.rs</em>
|
||
and place a function named <code>setup</code> in it, we can add some code to <code>setup</code> that
|
||
we want to call from multiple test functions in multiple test files:</p>
|
||
<p><span class="filename">Filename: tests/common.rs</span></p>
|
||
<pre><code class="language-rust noplayground">pub fn setup() {
|
||
// setup code specific to your library's tests would go here
|
||
}</code></pre>
|
||
<p>When we run the tests again, we’ll see a new section in the test output for the
|
||
<em>common.rs</em> file, even though this file doesn’t contain any test functions nor
|
||
did we call the <code>setup</code> function from anywhere:</p>
|
||
<pre><code class="language-console">$ cargo test
|
||
Compiling adder v0.1.0 (file:///projects/adder)
|
||
Finished `test` profile [unoptimized + debuginfo] target(s) in 0.89s
|
||
Running unittests src/lib.rs (target/debug/deps/adder-92948b65e88960b4)
|
||
|
||
running 1 test
|
||
test tests::internal ... ok
|
||
|
||
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
|
||
|
||
Running tests/common.rs (target/debug/deps/common-92948b65e88960b4)
|
||
|
||
running 0 tests
|
||
|
||
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
|
||
|
||
Running tests/integration_test.rs (target/debug/deps/integration_test-92948b65e88960b4)
|
||
|
||
running 1 test
|
||
test it_adds_two ... ok
|
||
|
||
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
|
||
|
||
Doc-tests adder
|
||
|
||
running 0 tests
|
||
|
||
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
|
||
|
||
</code></pre>
|
||
<p>Having <code>common</code> appear in the test results with <code>running 0 tests</code> displayed for
|
||
it is not what we wanted. We just wanted to share some code with the other
|
||
integration test files. To avoid having <code>common</code> appear in the test output,
|
||
instead of creating <em>tests/common.rs</em>, we’ll create <em>tests/common/mod.rs</em>. The
|
||
project directory now looks like this:</p>
|
||
<pre><code class="language-text">├── Cargo.lock
|
||
├── Cargo.toml
|
||
├── src
|
||
│ └── lib.rs
|
||
└── tests
|
||
├── common
|
||
│ └── mod.rs
|
||
└── integration_test.rs
|
||
</code></pre>
|
||
<p>This is the older naming convention that Rust also understands that we mentioned
|
||
in <a href="ch07-05-separating-modules-into-different-files.html#alternate-file-paths">“Alternate File Paths”</a><!-- ignore --> in Chapter 7. Naming the
|
||
file this way tells Rust not to treat the <code>common</code> module as an integration test
|
||
file. When we move the <code>setup</code> function code into <em>tests/common/mod.rs</em> and
|
||
delete the <em>tests/common.rs</em> file, the section in the test output will no longer
|
||
appear. Files in subdirectories of the <em>tests</em> directory don’t get compiled as
|
||
separate crates or have sections in the test output.</p>
|
||
<p>After we’ve created <em>tests/common/mod.rs</em>, we can use it from any of the
|
||
integration test files as a module. Here’s an example of calling the <code>setup</code>
|
||
function from the <code>it_adds_two</code> test in <em>tests/integration_test.rs</em>:</p>
|
||
<p><span class="filename">Filename: tests/integration_test.rs</span></p>
|
||
<pre><code class="language-rust ignore">use adder::add_two;
|
||
|
||
mod common;
|
||
|
||
#[test]
|
||
fn it_adds_two() {
|
||
common::setup();
|
||
|
||
let result = add_two(2);
|
||
assert_eq!(result, 4);
|
||
}</code></pre>
|
||
<p>Note that the <code>mod common;</code> declaration is the same as the module declaration
|
||
we demonstrated in Listing 7-21. Then, in the test function, we can call the
|
||
<code>common::setup()</code> function.</p>
|
||
<h4 id="integration-tests-for-binary-crates"><a class="header" href="#integration-tests-for-binary-crates">Integration Tests for Binary Crates</a></h4>
|
||
<p>If our project is a binary crate that only contains a <em>src/main.rs</em> file and
|
||
doesn’t have a <em>src/lib.rs</em> file, we can’t create integration tests in the
|
||
<em>tests</em> directory and bring functions defined in the <em>src/main.rs</em> file into
|
||
scope with a <code>use</code> statement. Only library crates expose functions that other
|
||
crates can use; binary crates are meant to be run on their own.</p>
|
||
<p>This is one of the reasons Rust projects that provide a binary have a
|
||
straightforward <em>src/main.rs</em> file that calls logic that lives in the
|
||
<em>src/lib.rs</em> file. Using that structure, integration tests <em>can</em> test the
|
||
library crate with <code>use</code> to make the important functionality available. If the
|
||
important functionality works, the small amount of code in the <em>src/main.rs</em>
|
||
file will work as well, and that small amount of code doesn’t need to be tested.</p>
|
||
<h2 id="summary"><a class="header" href="#summary">Summary</a></h2>
|
||
<p>Rust’s testing features provide a way to specify how code should function to
|
||
ensure that it continues to work as you expect, even as you make changes. Unit
|
||
tests exercise different parts of a library separately and can test private
|
||
implementation details. Integration tests check that many parts of the library
|
||
work together correctly, and they use the library’s public API to test the code
|
||
in the same way external code will use it. Even though Rust’s type system and
|
||
ownership rules help prevent some kinds of bugs, tests are still important to
|
||
reduce logic bugs having to do with how your code is expected to behave.</p>
|
||
<p>Let’s combine the knowledge you learned in this chapter and in previous
|
||
chapters to work on a project!</p>
|
||
|
||
</main>
|
||
|
||
<nav class="nav-wrapper" aria-label="Page navigation">
|
||
<!-- Mobile navigation buttons -->
|
||
<a rel="prev" href="ch11-02-running-tests.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
||
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M41.4 233.4c-12.5 12.5-12.5 32.8 0 45.3l160 160c12.5 12.5 32.8 12.5 45.3 0s12.5-32.8 0-45.3L109.3 256 246.6 118.6c12.5-12.5 12.5-32.8 0-45.3s-32.8-12.5-45.3 0l-160 160z"/></svg></span>
|
||
</a>
|
||
|
||
<a rel="next prefetch" href="ch12-00-an-io-project.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
||
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z"/></svg></span>
|
||
</a>
|
||
|
||
<div style="clear: both"></div>
|
||
</nav>
|
||
</div>
|
||
</div>
|
||
|
||
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
||
<a rel="prev" href="ch11-02-running-tests.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
||
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M41.4 233.4c-12.5 12.5-12.5 32.8 0 45.3l160 160c12.5 12.5 32.8 12.5 45.3 0s12.5-32.8 0-45.3L109.3 256 246.6 118.6c12.5-12.5 12.5-32.8 0-45.3s-32.8-12.5-45.3 0l-160 160z"/></svg></span>
|
||
</a>
|
||
|
||
<a rel="next prefetch" href="ch12-00-an-io-project.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
||
<span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M278.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-160 160c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L210.7 256 73.4 118.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l160 160z"/></svg></span>
|
||
</a>
|
||
</nav>
|
||
|
||
</div>
|
||
|
||
<template id=fa-eye><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 576 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M288 32c-80.8 0-145.5 36.8-192.6 80.6C48.6 156 17.3 208 2.5 243.7c-3.3 7.9-3.3 16.7 0 24.6C17.3 304 48.6 356 95.4 399.4C142.5 443.2 207.2 480 288 480s145.5-36.8 192.6-80.6c46.8-43.5 78.1-95.4 93-131.1c3.3-7.9 3.3-16.7 0-24.6c-14.9-35.7-46.2-87.7-93-131.1C433.5 68.8 368.8 32 288 32zM432 256c0 79.5-64.5 144-144 144s-144-64.5-144-144s64.5-144 144-144s144 64.5 144 144zM288 192c0 35.3-28.7 64-64 64c-11.5 0-22.3-3-31.6-8.4c-.2 2.8-.4 5.5-.4 8.4c0 53 43 96 96 96s96-43 96-96s-43-96-96-96c-2.8 0-5.6 .1-8.4 .4c5.3 9.3 8.4 20.1 8.4 31.6z"/></svg></span></template>
|
||
<template id=fa-eye-slash><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 640 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M38.8 5.1C28.4-3.1 13.3-1.2 5.1 9.2S-1.2 34.7 9.2 42.9l592 464c10.4 8.2 25.5 6.3 33.7-4.1s6.3-25.5-4.1-33.7L525.6 386.7c39.6-40.6 66.4-86.1 79.9-118.4c3.3-7.9 3.3-16.7 0-24.6c-14.9-35.7-46.2-87.7-93-131.1C465.5 68.8 400.8 32 320 32c-68.2 0-125 26.3-169.3 60.8L38.8 5.1zM223.1 149.5C248.6 126.2 282.7 112 320 112c79.5 0 144 64.5 144 144c0 24.9-6.3 48.3-17.4 68.7L408 294.5c5.2-11.8 8-24.8 8-38.5c0-53-43-96-96-96c-2.8 0-5.6 .1-8.4 .4c5.3 9.3 8.4 20.1 8.4 31.6c0 10.2-2.4 19.8-6.6 28.3l-90.3-70.8zm223.1 298L373 389.9c-16.4 6.5-34.3 10.1-53 10.1c-79.5 0-144-64.5-144-144c0-6.9 .5-13.6 1.4-20.2L83.1 161.5C60.3 191.2 44 220.8 34.5 243.7c-3.3 7.9-3.3 16.7 0 24.6c14.9 35.7 46.2 87.7 93 131.1C174.5 443.2 239.2 480 320 480c47.8 0 89.9-12.9 126.2-32.5z"/></svg></span></template>
|
||
<template id=fa-copy><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M502.6 70.63l-61.25-61.25C435.4 3.371 427.2 0 418.7 0H255.1c-35.35 0-64 28.66-64 64l.0195 256C192 355.4 220.7 384 256 384h192c35.2 0 64-28.8 64-64V93.25C512 84.77 508.6 76.63 502.6 70.63zM464 320c0 8.836-7.164 16-16 16H255.1c-8.838 0-16-7.164-16-16L239.1 64.13c0-8.836 7.164-16 16-16h128L384 96c0 17.67 14.33 32 32 32h47.1V320zM272 448c0 8.836-7.164 16-16 16H63.1c-8.838 0-16-7.164-16-16L47.98 192.1c0-8.836 7.164-16 16-16H160V128H63.99c-35.35 0-64 28.65-64 64l.0098 256C.002 483.3 28.66 512 64 512h192c35.2 0 64-28.8 64-64v-32h-47.1L272 448z"/></svg></span></template>
|
||
<template id=fa-play><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 384 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M73 39c-14.8-9.1-33.4-9.4-48.5-.9S0 62.6 0 80V432c0 17.4 9.4 33.4 24.5 41.9s33.7 8.1 48.5-.9L361 297c14.3-8.7 23-24.2 23-41s-8.7-32.2-23-41L73 39z"/></svg></span></template>
|
||
<template id=fa-clock-rotate-left><span class=fa-svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.2.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --><path d="M75 75L41 41C25.9 25.9 0 36.6 0 57.9V168c0 13.3 10.7 24 24 24H134.1c21.4 0 32.1-25.9 17-41l-30.8-30.8C155 85.5 203 64 256 64c106 0 192 86 192 192s-86 192-192 192c-40.8 0-78.6-12.7-109.7-34.4c-14.5-10.1-34.4-6.6-44.6 7.9s-6.6 34.4 7.9 44.6C151.2 495 201.7 512 256 512c141.4 0 256-114.6 256-256S397.4 0 256 0C185.3 0 121.3 28.7 75 75zm181 53c-13.3 0-24 10.7-24 24V256c0 6.4 2.5 12.5 7 17l72 72c9.4 9.4 24.6 9.4 33.9 0s9.4-24.6 0-33.9l-65-65V152c0-13.3-10.7-24-24-24z"/></svg></span></template>
|
||
|
||
|
||
|
||
<script>
|
||
window.playground_copyable = true;
|
||
</script>
|
||
|
||
|
||
<script src="elasticlunr-ef4e11c1.min.js"></script>
|
||
<script src="mark-09e88c2c.min.js"></script>
|
||
<script src="searcher-09f2665d.js"></script>
|
||
|
||
<script src="clipboard-1626706a.min.js"></script>
|
||
<script src="highlight-abc7f01d.js"></script>
|
||
<script src="book-c22b7243.js"></script>
|
||
|
||
<!-- Custom JS scripts -->
|
||
<script src="ferris-2317480c.js"></script>
|
||
|
||
|
||
|
||
</div>
|
||
</body>
|
||
</html>
|