When there are several providers of the functionality that have compatible APIs, you can use Best. With modules that just export functions, you simply replace the use line:

use YAML;   # This module is slow!

# So if you want to try a faster one first:

use Best qw(YAML::Syck   YAML);

print Dump({ some => 'hash' }); # Dumping provided by Best Possible YA
+ML module
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There's knobs you can use to rewire stuff as in your is_deeply example; and a which function is provided so you can get the name of the module that was actually loaded to write factories with.

use Best qw(OOPishProv AnotherOOPyProv::Serving::As::Fallback);

my $obj = Best->which("OOPishProv")->new;
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If you're out for less syntax, you might like to try the possibly too-magical Class::TransparentFactory.