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                         <h1 id="the-rustdoc-test-suite"><a class="header" href="#the-rustdoc-test-suite">The <code>rustdoc</code> test suite</a></h1>
 <p>This page is about the test suite named <code>rustdoc</code> used to test the HTML output of <code>rustdoc</code>.
 For other rustdoc-specific test suites, see <a href="../tests/compiletest.html#rustdoc-test-suites">Rustdoc test suites</a>.</p>
 <p>Each test file in this test suite is simply a Rust source file <code>file.rs</code> sprinkled with
 so-called <em>directives</em> located inside normal Rust code comments.
 These come in two flavors: <em>Compiletest</em> and <em>HtmlDocCk</em>.</p>
 <p>To learn more about the former, read <a href="../tests/directives.html">Compiletest directives</a>.
 For the latter, continue reading.</p>
 <p>Internally, <a href="../tests/compiletest.html"><code>compiletest</code></a> invokes the supplementary checker script <a href="https://github.com/rust-lang/rust/blob/master/src/etc/htmldocck.py"><code>htmldocck.py</code></a>.</p>
 <h2 id="htmldocck-directives"><a class="header" href="#htmldocck-directives">HtmlDocCk Directives</a></h2>
 <p>Directives to HtmlDocCk are assertions that place constraints on the generated HTML.
 They look similar to those given to <code>compiletest</code> in that they take the form of <code>//@</code> comments
 but ultimately, they are completely distinct and processed by different programs.</p>
 <p><a href="https://en.wikipedia.org/wiki/XPath">XPath</a> is used to query parts of the HTML document tree.</p>
 <p><strong>Introductory example</strong>:</p>
 <pre><code class="language-rust ignore (illustrative)">//@ has file/type.Alias.html
 //@ has - '//*[@class="rust item-decl"]//code' 'type Alias = Option&lt;i32&gt;;'
 pub type Alias = Option&lt;i32&gt;;</code></pre>
 <p>Here, we check that documentation generated for crate <code>file</code> contains a page for the
 public type alias <code>Alias</code> where the code block that is found at the top contains the
 expected rendering of the item. The <code>//*[@class="rust item-decl"]//code</code> is an XPath
 expression.</p>
 <p>Conventionally, you place these directives directly above the thing they are meant to test.
 Technically speaking however, they don't need to be as HtmlDocCk only looks for the directives.</p>
 <p>All directives take a <code>PATH</code> argument.
 To avoid repetition, <code>-</code> can be passed to it to re-use the previous <code>PATH</code> argument.
 Since the path contains the name of the crate, it is conventional to add a
 <code>#![crate_name = "foo"]</code> attribute to the crate root to shorten the resulting path.</p>
 <p>All arguments take the form of shell-style (single or double) quoted strings,
 with the exception of <code>COUNT</code> and the special <code>-</code> form of <code>PATH</code>.</p>
 <p>All directives (except <code>files</code>) can be <em>negated</em> by putting a <code>!</code> in front of their name.
 Before you add negated directives, please read about <a href="#caveats">their caveats</a>.</p>
 <p>Similar to shell commands,
 directives can extend across multiple lines if their last char is <code>\</code>.
 In this case, the start of the next line should be <code>//</code>, with no <code>@</code>.</p>
 <p>Similar to compiletest directives, besides a space you can also use a colon <code>:</code> to separate
 the directive name and the arguments, however a space is preferred for HtmlDocCk directives.</p>
 <p>Use the special string <code>{{channel}}</code> in XPaths, <code>PATTERN</code> arguments and <a href="#snapshot">snapshot files</a>
 if you'd like to refer to the URL <code>https://doc.rust-lang.org/CHANNEL</code> where <code>CHANNEL</code> refers to the
 current release channel (e.g, <code>stable</code> or <code>nightly</code>).</p>
 <p>Listed below are all possible directives:</p>
 <h3 id="has"><a class="header" href="#has"><code>has</code></a></h3>
 <blockquote>
 <p>Usage 1: <code>//@ has PATH</code></p>
 </blockquote>
 <p>Check that the file given by <code>PATH</code> exists.</p>
 <blockquote>
 <p>Usage 2: <code>//@ has PATH XPATH PATTERN</code></p>
 </blockquote>
 <p>Checks that the text of each element / attribute / text selected by <code>XPATH</code> in the
 whitespace-normalized<sup class="footnote-reference" id="fr-1-1"><a href="#footnote-1">1</a></sup> file given by <code>PATH</code> matches the
 (also whitespace-normalized) string <code>PATTERN</code>.</p>
 <p><strong>Tip</strong>: If you'd like to avoid whitespace normalization and/or if you'd like to match with a regex,
 use <code>matches</code> instead.</p>
 <h3 id="hasraw"><a class="header" href="#hasraw"><code>hasraw</code></a></h3>
 <blockquote>
 <p>Usage: <code>//@ hasraw PATH PATTERN</code></p>
 </blockquote>
 <p>Checks that the contents of the whitespace-normalized<sup class="footnote-reference" id="fr-1-2"><a href="#footnote-1">1</a></sup> file given by <code>PATH</code>
 matches the (also whitespace-normalized) string <code>PATTERN</code>.</p>
 <p><strong>Tip</strong>: If you'd like to avoid whitespace normalization and / or if you'd like to match with a
 regex, use <code>matchesraw</code> instead.</p>
 <h3 id="matches"><a class="header" href="#matches"><code>matches</code></a></h3>
 <blockquote>
 <p>Usage: <code>//@ matches PATH XPATH PATTERN</code></p>
 </blockquote>
 <p>Checks that the text of each element / attribute / text selected by <code>XPATH</code> in the
 file given by <code>PATH</code> matches the Python-flavored<sup class="footnote-reference" id="fr-2-1"><a href="#footnote-2">2</a></sup> regex <code>PATTERN</code>.</p>
 <h3 id="matchesraw"><a class="header" href="#matchesraw"><code>matchesraw</code></a></h3>
 <blockquote>
 <p>Usage: <code>//@ matchesraw PATH PATTERN</code></p>
 </blockquote>
 <p>Checks that the contents of the file given by <code>PATH</code> matches the
 Python-flavored<sup class="footnote-reference" id="fr-2-2"><a href="#footnote-2">2</a></sup> regex <code>PATTERN</code>.</p>
 <h3 id="count"><a class="header" href="#count"><code>count</code></a></h3>
 <blockquote>
 <p>Usage: <code>//@ count PATH XPATH COUNT</code></p>
 </blockquote>
 <p>Checks that there are exactly <code>COUNT</code> matches for <code>XPATH</code> within the file given by <code>PATH</code>.</p>
 <h3 id="snapshot"><a class="header" href="#snapshot"><code>snapshot</code></a></h3>
 <blockquote>
 <p>Usage: <code>//@ snapshot NAME PATH XPATH</code></p>
 </blockquote>
 <p>Checks that the element / text selected by <code>XPATH</code> in the file given by <code>PATH</code> matches the
 pre-recorded subtree or text (the "snapshot") in file <code>FILE_STEM.NAME.html</code> where <code>FILE_STEM</code>
 is the file stem of the test file.</p>
 <p>Pass the <code>--bless</code> option to <code>compiletest</code> to accept the current subtree/text as expected.
 This will overwrite the aforementioned file (or create it if it doesn't exist). It will
 automatically normalize the channel-dependent URL <code>https://doc.rust-lang.org/CHANNEL</code> to
 the special string <code>{{channel}}</code>.</p>
 <h3 id="has-dir"><a class="header" href="#has-dir"><code>has-dir</code></a></h3>
 <blockquote>
 <p>Usage: <code>//@ has-dir PATH</code></p>
 </blockquote>
 <p>Checks for the existence of the directory given by <code>PATH</code>.</p>
 <h3 id="files"><a class="header" href="#files"><code>files</code></a></h3>
 <blockquote>
 <p>Usage: <code>//@ files PATH ENTRIES</code></p>
 </blockquote>
 <p>Checks that the directory given by <code>PATH</code> contains exactly <code>ENTRIES</code>.
 <code>ENTRIES</code> is a Python-like list of strings inside a quoted string.</p>
 <p><strong>Example</strong>: <code>//@ files "foo/bar" '["index.html", "sidebar-items.js"]'</code></p>
 <h2 id="compiletest-directives-brief"><a class="header" href="#compiletest-directives-brief">Compiletest Directives (Brief)</a></h2>
 <p>As mentioned in the introduction, you also have access to <a href="../tests/directives.html">compiletest directives</a>.
 Most importantly, they allow you to register auxiliary crates and
 to pass flags to the <code>rustdoc</code> binary under test.
 It's <em>strongly recommended</em> to read that chapter if you don't know anything about them yet.</p>
 <p>Here are some details that are relevant to this test suite specifically:</p>
 <ul>
 <li>While you can use both <code>//@ compile-flags</code> and <code>//@ doc-flags</code> to pass flags to <code>rustdoc</code>,
 prefer to user the latter to show intent. The former is meant for <code>rustc</code>.</li>
 <li>Add <code>//@ build-aux-docs</code> to the test file that has auxiliary crates to not only compile the
 auxiliaries with <code>rustc</code> but to also document them with <code>rustdoc</code>.</li>
 </ul>
 <h2 id="caveats"><a class="header" href="#caveats">Caveats</a></h2>
 <p>Testing for the absence of an element or a piece of text is quite fragile and not very future proof.</p>
 <p>It's not unusual that the <em>shape</em> of the generated HTML document tree changes from time to time.
 This includes for example renamings of CSS classes.</p>
 <p>Whenever that happens, <em>positive</em> checks will either continue to match the intended element /
 attribute / text (if their XPath expression is general / loose enough) and
 thus continue to test the correct thing or they won't in which case they would fail thereby
 forcing the author of the change to look at them.</p>
 <p>Compare that to <em>negative</em> checks (e.g., <code>//@ !has PATH XPATH PATTERN</code>) which won't fail if their
 XPath expression "no longer" matches. The author who changed "the shape" thus won't get notified and
 as a result someone else can unintentionally reintroduce <code>PATTERN</code> into the generated docs without
 the original negative check failing.</p>
 <p><strong>Note</strong>: Please avoid the use of <em>negated</em> checks!</p>
 <p><strong>Tip</strong>: If you can't avoid it, please <strong>always</strong> pair it with an analogous positive check in the
 immediate vicinity, so people changing "the shape" have a chance to notice and to update the
 negated check!</p>
 <h2 id="limitations"><a class="header" href="#limitations">Limitations</a></h2>
 <p>HtmlDocCk uses the XPath implementation from the Python standard library.
 This leads to several limitations:</p>
 <ul>
 <li>All <code>XPATH</code> arguments must start with <code>//</code> due to a flaw in the implementation.</li>
 <li>Many XPath features (functions, axies, etc.) are not supported.</li>
 <li>Only well-formed HTML can be parsed (hopefully rustdoc doesn't output mismatched tags).</li>
 </ul>
 <p>Furthmore, compiletest <a href="../tests/compiletest.html#revisions">revisions</a> are not supported.</p>
 <hr>
 <ol class="footnote-definition"><li id="footnote-1">
 <p>Whitespace normalization means that all spans of consecutive whitespace are replaced with a single space. <a href="#fr-1-1">↩</a> <a href="#fr-1-2">↩2</a></p>
 </li>
 <li id="footnote-2">
 <p>They are Unicode aware (flag <code>UNICODE</code> is set), match case-sensitively and in single-line mode. <a href="#fr-2-1">↩</a> <a href="#fr-2-2">↩2</a></p>
 </li>
 </ol>
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	<h1 id="the-rustdoc-test-suite"><a class="header" href="#the-rustdoc-test-suite">The <code>rustdoc</code> test suite</a></h1>
	<p>This page is about the test suite named <code>rustdoc</code> used to test the HTML output of <code>rustdoc</code>.
	For other rustdoc-specific test suites, see <a href="../tests/compiletest.html#rustdoc-test-suites">Rustdoc test suites</a>.</p>
	<p>Each test file in this test suite is simply a Rust source file <code>file.rs</code> sprinkled with
	so-called <em>directives</em> located inside normal Rust code comments.
	These come in two flavors: <em>Compiletest</em> and <em>HtmlDocCk</em>.</p>
	<p>To learn more about the former, read <a href="../tests/directives.html">Compiletest directives</a>.
	For the latter, continue reading.</p>
	<p>Internally, <a href="../tests/compiletest.html"><code>compiletest</code></a> invokes the supplementary checker script <a href="https://github.com/rust-lang/rust/blob/master/src/etc/htmldocck.py"><code>htmldocck.py</code></a>.</p>
	<h2 id="htmldocck-directives"><a class="header" href="#htmldocck-directives">HtmlDocCk Directives</a></h2>
	<p>Directives to HtmlDocCk are assertions that place constraints on the generated HTML.
	They look similar to those given to <code>compiletest</code> in that they take the form of <code>//@</code> comments
	but ultimately, they are completely distinct and processed by different programs.</p>
	<p><a href="https://en.wikipedia.org/wiki/XPath">XPath</a> is used to query parts of the HTML document tree.</p>
	<p><strong>Introductory example</strong>:</p>
	<pre><code class="language-rust ignore (illustrative)">//@ has file/type.Alias.html
	//@ has - '//*[@class="rust item-decl"]//code' 'type Alias = Option<i32>;'
	pub type Alias = Option<i32>;</code></pre>
	<p>Here, we check that documentation generated for crate <code>file</code> contains a page for the
	public type alias <code>Alias</code> where the code block that is found at the top contains the
	expected rendering of the item. The <code>//*[@class="rust item-decl"]//code</code> is an XPath
	expression.</p>
	<p>Conventionally, you place these directives directly above the thing they are meant to test.
	Technically speaking however, they don't need to be as HtmlDocCk only looks for the directives.</p>
	<p>All directives take a <code>PATH</code> argument.
	To avoid repetition, <code>-</code> can be passed to it to re-use the previous <code>PATH</code> argument.
	Since the path contains the name of the crate, it is conventional to add a
	<code>#![crate_name = "foo"]</code> attribute to the crate root to shorten the resulting path.</p>
	<p>All arguments take the form of shell-style (single or double) quoted strings,
	with the exception of <code>COUNT</code> and the special <code>-</code> form of <code>PATH</code>.</p>
	<p>All directives (except <code>files</code>) can be <em>negated</em> by putting a <code>!</code> in front of their name.
	Before you add negated directives, please read about <a href="#caveats">their caveats</a>.</p>
	<p>Similar to shell commands,
	directives can extend across multiple lines if their last char is <code>\</code>.
	In this case, the start of the next line should be <code>//</code>, with no <code>@</code>.</p>
	<p>Similar to compiletest directives, besides a space you can also use a colon <code>:</code> to separate
	the directive name and the arguments, however a space is preferred for HtmlDocCk directives.</p>
	<p>Use the special string <code>{{channel}}</code> in XPaths, <code>PATTERN</code> arguments and <a href="#snapshot">snapshot files</a>
	if you'd like to refer to the URL <code>https://doc.rust-lang.org/CHANNEL</code> where <code>CHANNEL</code> refers to the
	current release channel (e.g, <code>stable</code> or <code>nightly</code>).</p>
	<p>Listed below are all possible directives:</p>
	<h3 id="has"><a class="header" href="#has"><code>has</code></a></h3>
	<blockquote>
	<p>Usage 1: <code>//@ has PATH</code></p>
	</blockquote>
	<p>Check that the file given by <code>PATH</code> exists.</p>
	<blockquote>
	<p>Usage 2: <code>//@ has PATH XPATH PATTERN</code></p>
	</blockquote>
	<p>Checks that the text of each element / attribute / text selected by <code>XPATH</code> in the
	whitespace-normalized<sup class="footnote-reference" id="fr-1-1"><a href="#footnote-1">1</a></sup> file given by <code>PATH</code> matches the
	(also whitespace-normalized) string <code>PATTERN</code>.</p>
	<p><strong>Tip</strong>: If you'd like to avoid whitespace normalization and/or if you'd like to match with a regex,
	use <code>matches</code> instead.</p>
	<h3 id="hasraw"><a class="header" href="#hasraw"><code>hasraw</code></a></h3>
	<blockquote>
	<p>Usage: <code>//@ hasraw PATH PATTERN</code></p>
	</blockquote>
	<p>Checks that the contents of the whitespace-normalized<sup class="footnote-reference" id="fr-1-2"><a href="#footnote-1">1</a></sup> file given by <code>PATH</code>
	matches the (also whitespace-normalized) string <code>PATTERN</code>.</p>
	<p><strong>Tip</strong>: If you'd like to avoid whitespace normalization and / or if you'd like to match with a
	regex, use <code>matchesraw</code> instead.</p>
	<h3 id="matches"><a class="header" href="#matches"><code>matches</code></a></h3>
	<blockquote>
	<p>Usage: <code>//@ matches PATH XPATH PATTERN</code></p>
	</blockquote>
	<p>Checks that the text of each element / attribute / text selected by <code>XPATH</code> in the
	file given by <code>PATH</code> matches the Python-flavored<sup class="footnote-reference" id="fr-2-1"><a href="#footnote-2">2</a></sup> regex <code>PATTERN</code>.</p>
	<h3 id="matchesraw"><a class="header" href="#matchesraw"><code>matchesraw</code></a></h3>
	<blockquote>
	<p>Usage: <code>//@ matchesraw PATH PATTERN</code></p>
	</blockquote>
	<p>Checks that the contents of the file given by <code>PATH</code> matches the
	Python-flavored<sup class="footnote-reference" id="fr-2-2"><a href="#footnote-2">2</a></sup> regex <code>PATTERN</code>.</p>
	<h3 id="count"><a class="header" href="#count"><code>count</code></a></h3>
	<blockquote>
	<p>Usage: <code>//@ count PATH XPATH COUNT</code></p>
	</blockquote>
	<p>Checks that there are exactly <code>COUNT</code> matches for <code>XPATH</code> within the file given by <code>PATH</code>.</p>
	<h3 id="snapshot"><a class="header" href="#snapshot"><code>snapshot</code></a></h3>
	<blockquote>
	<p>Usage: <code>//@ snapshot NAME PATH XPATH</code></p>
	</blockquote>
	<p>Checks that the element / text selected by <code>XPATH</code> in the file given by <code>PATH</code> matches the
	pre-recorded subtree or text (the "snapshot") in file <code>FILE_STEM.NAME.html</code> where <code>FILE_STEM</code>
	is the file stem of the test file.</p>
	<p>Pass the <code>--bless</code> option to <code>compiletest</code> to accept the current subtree/text as expected.
	This will overwrite the aforementioned file (or create it if it doesn't exist). It will
	automatically normalize the channel-dependent URL <code>https://doc.rust-lang.org/CHANNEL</code> to
	the special string <code>{{channel}}</code>.</p>
	<h3 id="has-dir"><a class="header" href="#has-dir"><code>has-dir</code></a></h3>
	<blockquote>
	<p>Usage: <code>//@ has-dir PATH</code></p>
	</blockquote>
	<p>Checks for the existence of the directory given by <code>PATH</code>.</p>
	<h3 id="files"><a class="header" href="#files"><code>files</code></a></h3>
	<blockquote>
	<p>Usage: <code>//@ files PATH ENTRIES</code></p>
	</blockquote>
	<p>Checks that the directory given by <code>PATH</code> contains exactly <code>ENTRIES</code>.
	<code>ENTRIES</code> is a Python-like list of strings inside a quoted string.</p>
	<p><strong>Example</strong>: <code>//@ files "foo/bar" '["index.html", "sidebar-items.js"]'</code></p>
	<h2 id="compiletest-directives-brief"><a class="header" href="#compiletest-directives-brief">Compiletest Directives (Brief)</a></h2>
	<p>As mentioned in the introduction, you also have access to <a href="../tests/directives.html">compiletest directives</a>.
	Most importantly, they allow you to register auxiliary crates and
	to pass flags to the <code>rustdoc</code> binary under test.
	It's <em>strongly recommended</em> to read that chapter if you don't know anything about them yet.</p>
	<p>Here are some details that are relevant to this test suite specifically:</p>
	<ul>
	<li>While you can use both <code>//@ compile-flags</code> and <code>//@ doc-flags</code> to pass flags to <code>rustdoc</code>,
	prefer to user the latter to show intent. The former is meant for <code>rustc</code>.</li>
	<li>Add <code>//@ build-aux-docs</code> to the test file that has auxiliary crates to not only compile the
	auxiliaries with <code>rustc</code> but to also document them with <code>rustdoc</code>.</li>
	</ul>
	<h2 id="caveats"><a class="header" href="#caveats">Caveats</a></h2>
	<p>Testing for the absence of an element or a piece of text is quite fragile and not very future proof.</p>
	<p>It's not unusual that the <em>shape</em> of the generated HTML document tree changes from time to time.
	This includes for example renamings of CSS classes.</p>
	<p>Whenever that happens, <em>positive</em> checks will either continue to match the intended element /
	attribute / text (if their XPath expression is general / loose enough) and
	thus continue to test the correct thing or they won't in which case they would fail thereby
	forcing the author of the change to look at them.</p>
	<p>Compare that to <em>negative</em> checks (e.g., <code>//@ !has PATH XPATH PATTERN</code>) which won't fail if their
	XPath expression "no longer" matches. The author who changed "the shape" thus won't get notified and
	as a result someone else can unintentionally reintroduce <code>PATTERN</code> into the generated docs without
	the original negative check failing.</p>
	<p><strong>Note</strong>: Please avoid the use of <em>negated</em> checks!</p>
	<p><strong>Tip</strong>: If you can't avoid it, please <strong>always</strong> pair it with an analogous positive check in the
	immediate vicinity, so people changing "the shape" have a chance to notice and to update the
	negated check!</p>
	<h2 id="limitations"><a class="header" href="#limitations">Limitations</a></h2>
	<p>HtmlDocCk uses the XPath implementation from the Python standard library.
	This leads to several limitations:</p>
	<ul>
	<li>All <code>XPATH</code> arguments must start with <code>//</code> due to a flaw in the implementation.</li>
	<li>Many XPath features (functions, axies, etc.) are not supported.</li>
	<li>Only well-formed HTML can be parsed (hopefully rustdoc doesn't output mismatched tags).</li>
	</ul>
	<p>Furthmore, compiletest <a href="../tests/compiletest.html#revisions">revisions</a> are not supported.</p>
	<hr>
	<ol class="footnote-definition"><li id="footnote-1">
	<p>Whitespace normalization means that all spans of consecutive whitespace are replaced with a single space. <a href="#fr-1-1">↩</a> <a href="#fr-1-2">↩2</a></p>
	</li>
	<li id="footnote-2">
	<p>They are Unicode aware (flag <code>UNICODE</code> is set), match case-sensitively and in single-line mode. <a href="#fr-2-1">↩</a> <a href="#fr-2-2">↩2</a></p>
	</li>
	</ol>
	</main>

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