Modernize C++ tests

[cyyever]

Description

Modernize test code.

[rwgk]

I'd rather not make these changes.

E.g.

@@ -92,8 +93,8 @@ TEST_SUBMODULE(class_, m) {
     // test_inheritance
     class Pet {
     public:
-        Pet(const std::string &name, const std::string &species)
-            : m_name(name), m_species(species) {}
+        Pet(std::string name, std::string species)
+            : m_name(std::move(name)), m_species(std::move(species)) {}
         std::string name() const { return m_name; }
         std::string species() const { return m_species; }

That a loss of readability IMO. const in the signature is clear. Scattering std::move() around in the implementation is just clutter in comparison.

Is this a big deal one way or another? — I don't think so. Better leave as is. Better invest time in something that matters more.