Test, if the conditional attribute value works with snippets.

>>>>templates/test.tpl
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<opt:root>
<opt:snippet name="values1">
	<opt:value test="$val1 == 'foo'">a</opt:value>
	<opt:value test="$val1 == 'bar'">b</opt:value>
</opt:snippet>
<opt:snippet name="values2">
	<opt:value test="$val2 == 'foo'">a</opt:value>
	<opt:value test="$val2 == 'bar'">b</opt:value>
</opt:snippet>
<foo>
<opt:attribute name="class" str:value="c" opt:use="values1" />
</foo>
<foo>
<opt:attribute name="class" str:value="c" opt:use="values2" />
</foo>
</opt:root>

>>>>data.php
$view->val1 = 'foo';
$view->val2 = 'joe';

>>>>expected.txt
OUTPUT

>>>>result.txt
<foo class="a">
</foo>
<foo class="c">
</foo>