3 ms·

how much unit testing do you do?

• palish 16y ago
  A better question might be, "Would this pattern impact our ability to write unit tests?" I believe the answer is "No." Let's say the module Foo depends on the Graphics subsystem. That is, Foo.cpp has the code: #include "GrSubsys.h" //------------------------------------------------------- Foo::Foo( const string& name ) { // fetch a handle to our model (loading it if necessary). _model = gGrSubsys->GetModel( "models/" + name ); } //------------------------------------------------------- bool Foo::IsValid() { return ( _model != NULL ); } In order to write a unit test that takes into account the aforementioned Singleton pattern, you might write: //------------------------------------------------------- void Test_EngineComponents() { // prepare for science. AppStartup(); //========================== // Test #1 - Foo //========================== { // load a Foo entity. Foo* sunTzu = new Foo( "test/warlord" ); // verify the entity loaded successfully. assert( sunTzu->IsValid() ); // shutdown. delete sunTzu; } // conclude our science. AppShutdown(); } and AppStartup() is the function which initializes the subsystem singletons (and those will initialize their manager singletons). It's about discipline. Any fool can butcher with any tool.
  • hartror 16y ago
    Unless I have missed something about unit testing somewhere I am pretty sure that fails the "unit" part of unit testing. Unless that "#include GrSubsys.h" is actually importing a mock graphics subsystem.
    • palish 16y ago
      A mock graphics subsystem isn't possible since it depends directly on the video card.
      • hartror 16y ago
        Sorry fella but you don't understand the concept of unit testing. I suggest you do some reading on the subject. http://en.wikipedia.org/wiki/Unit_testing http://en.wikipedia.org/wiki/Unit_testing
        • palish 16y ago
          "In a unit test, mock objects can simulate the behavior of complex, real (non-mock) objects and are therefore useful when a real object is impractical or impossible to incorporate into a unit test." Why would you want to simulate the graphics subsystem (and therefore the video card)? The goal here isn't performance testing. It's to check whether the engine works.
          • hartror 16y ago
            You aren't testing the engine. You are testing that the unit, in your example the class Foo, responds correctly to the state and inputs you provide it. Decoupling those responses from other units such as the graphics subsystem gives you the assurance that under the tested conditions the unit works as intended. What you are talking about is a regression or functional test. Same genus different species, still very useful but not the same tool. Edit: Going to bed, if someone would like to explain by morning why this needed to be down voted so brutally I would be much obliged!
            • seabee 16y ago
              It's impossible to unit test a component whose criteria for 'working' is tightly coupled to dependencies out of your control (video hardware & drivers). Thus you'll never be able to unit-test a video game completely. Or even fulfill other forms of testing with the same breadth as is possible in other software, unless you have every possible configuration to test on, or stick with consoles. Games are among the buggiest of all software, but it's not for want of trying!
              • rapala 16y ago