Split out some of the test core into its own TU.

This might cut down on test build times?  It will let
me polish up some of this stuff without needing to recompile
some things.

Testing/test.cc

@@ -0,0 +1,80 @@
+static_assert( __cplusplus > 2020'00 );
+
+#include "test.h"
+
+namespace Alepha::Hydrogen::Testing::detail::testing
+{
+	StaticValue< std::vector< std::tuple< std::string, bool, std::function< void() > > > > registry;
+
+	TestRegistration
+	impl::operator <= ( TestName name, std::function< void () > test )
+	{
+		if( C::debugTestRegistration ) std::cerr << "Attempting to register: " << name.name << std::endl;
+
+		registry().emplace_back( name.name, name.disabled, test );
+		assert( not registry().empty() );
+		assert( std::get< 1 >( registry().back() ) == name.disabled );
+
+		return {};
+	};
+
+	[[nodiscard]] int
+	exports::runAllTests( const std::vector< std::string > selections )
+	{
+		if( C::debugTestRun )
+		{
+			std::cerr << "Going to run all tests.  (I see " << registry().size() << " tests.)" << std::endl;
+		}
+		bool failed= false;
+		const auto selected= [ selections ]( const std::string test )
+		{
+			for( const auto &selection: selections )
+			{
+				if( test.find( selection ) != std::string::npos ) return true;
+			}
+			return empty( selections );
+		};
+
+		const auto explicitlyNamed= [ selections ]( const std::string s )
+		{
+			return std::find( begin( selections ), end( selections ), s ) != end( selections );
+		};
+
+		for( const auto &[ name, disabled, test ]: registry() )
+		{
+			if( C::debugTestRun ) std::cerr << "Trying test " << name << std::endl;
+
+			if( explicitlyNamed( name ) or not disabled and selected( name ) )
+			{
+				std::cout << C::testInfo << "BEGIN" << resetStyle << "   : " << name << std::endl;
+				try
+				{
+					test();
+					std::cout << "  " << C::testPass << "SUCCESS" << resetStyle << ": " << name << std::endl;
+				}
+				catch( ... )
+				{
+					try
+					{
+						failed= true;
+						std::cout << "  " << C::testFail << "FAILURE" << resetStyle << ": " << name;
+						throw;
+					}
+					catch( const TestFailure &fail ) { std::cout << " -- " <<  fail.failureCount << " failures."; }
+					catch( ... ) { std::cout << " --  unknown failure count"; }
+					std::cout << std::endl;
+				}
+
+				std::cout << C::testInfo << "FINISHED" << resetStyle << ": " << name << std::endl;
+			}
+		}
+		
+		return failed ? EXIT_FAILURE : EXIT_SUCCESS;
+	}
+
+	[[nodiscard]] int
+	exports::runAllTests( const argcnt_t argcnt, const argvec_t argvec )
+	{
+		return runAllTests( { argvec + 1, argvec + argcnt } );
+	}
+}