Add test cases for attribute highlighting

Author: ewwwin

test/markup/rust/attributes.expect.txt

@@ -0,0 +1,18 @@
+<span class="hljs-meta">#[foo]</span>
+<span class="hljs-meta">#![foo]</span>
+
+<span class="hljs-meta">#[foo(bar)]</span>
+<span class="hljs-meta">#[foo = bar]</span>
+<span class="hljs-meta">#[foo(<span class="hljs-string">&quot;a \&quot;b\&quot; c&quot;</span>)]</span>
+<span class="hljs-meta">#[foo(bar = [a, b, c])]</span>
+<span class="hljs-meta">#[foo[bar]]</span>
+<span class="hljs-meta">#[foo{bar}]</span>
+
+<span class="hljs-meta">#![no_std]</span>
+<span class="hljs-meta">#[doc = <span class="hljs-string">&quot;example&quot;</span>]</span>
+<span class="hljs-meta">#[allow(unused, clippy::inline_always)]</span>
+<span class="hljs-meta">#[macro_use(foo, bar)]</span>
+<span class="hljs-meta">#[link(name = <span class="hljs-string">&quot;CoreFoundation&quot;</span>, kind = <span class="hljs-string">&quot;framework&quot;</span>)]</span>
+
+<span class="hljs-meta">#[rtic::app(device = lm3s6965, dispatchers = [UART0, UART1])]</span>
+<span class="hljs-meta">#[task(binds = USB_OTG1, local = [poller])]</span>

test/markup/rust/attributes.txt

@@ -0,0 +1,18 @@
+#[foo]
+#![foo]
+
+#[foo(bar)]
+#[foo = bar]
+#[foo("a \"b\" c")]
+#[foo(bar = [a, b, c])]
+#[foo[bar]]
+#[foo{bar}]
+
+#![no_std]
+#[doc = "example"]
+#[allow(unused, clippy::inline_always)]
+#[macro_use(foo, bar)]
+#[link(name = "CoreFoundation", kind = "framework")]
+
+#[rtic::app(device = lm3s6965, dispatchers = [UART0, UART1])]
+#[task(binds = USB_OTG1, local = [poller])]