6. Automatic testing

Usually you implement some algorithms, test them - and they work. But often you modify your code later, and it happes that you break code that worked before. It often takes a long time to find these errors.

For that reason it is a good idea to add a test-suite of well chosen tests that verify the individual units of your library.

We are going to use Catch2 for setting up such tests.

Now, merge the branch catch into your project. It gives you an extra directory tests containing the test suite.

TEST_CASE( "bla-tests", "[vector size test]" ) {
  Vector<double> x(5);
  Vector<double> y = x;
  REQUIRE(y.size() == 5);
}

TEST_CASE( "bla-tests", "[vector add and scale test]" ) {
  Vector<double> x(5);
  x = 3;
  Vector<double> y = x + x + (-2) * x + x;
  REQUIRE(y(0) == 3); 
}

TEST_CASE( "bla-tests", "[buggy vector add and scale test]" ) {
  Vector<double> x(5);
  x = 3;
  Vector<double> y = x + x + (-2) * x + x;
  REQUIRE(y(0) == 4);  // wrong test !!
}

Compiling and running the tests will produce the following output:

/Users/joachim/texjs/lva/IntroSC/ASC-bla/tests/tests_vector.cpp:27: FAILED:
   REQUIRE( y(0) == 4 )
with expansion:
  3.0 == 4

===============================================================================
test cases: 3 | 2 passed | 1 failed
assertions: 3 | 2 passed | 1 failed

Actually, not the vector class, but the test case is buggy.

In vs-code, you can use the testing symbol to run the tests:

One can set up the GitHub server such that with every commit the test-suite is run automatically, see Continuous Integraton. That should help to detect errors at an early stage.