Missing tests for `gen_pauli_x` and `gen_pauli_z`

Related to #478

Tests for these functions are missing from toqito/matrices/tests

Tests in `matrices/tests`	Defined functions in `matrices/`

https://github.com/vprusso/toqito/tree/eb5820721884dae5b9fdaad68913b2d96785167d/toqito/matrices/tests

Interestingly enough, both these functions are not flagged as uncovered by pytest.

This issue is to find where the tests for these functions are or add files to test them. If it's the latter, need to figure out why pytest is not flagging these.

@vprusso Looking at the commit history for both functions, I don't think the tests for these functions were added. Wanted to double-check with you as to what might have happened. Maybe the tests got lost in other modules?

Looking through the old commits, I don't see the tests in the previous tests directory.

We changed the directory in #257 and if I look at another PR #255 merged before the restructured directory, the tests don't exist where we expect them to be.

https://github.com/vprusso/toqito/tree/63c86059f06f994e23be93f3a4626c0b1717b464/tests/test_matrices

Maybe this is also a pytest issue as it does not flag the uncovered lines in addition to missing tests.

Interestingly, if I look at the full coverage report, pytest thinks there are tests for these functions. I don't know what BrPart is though in the screenshot below.

Maybe pytest thinks the lines below cover the expected output of other functions.

toqito/toqito/matrices/gen_pauli.py

Lines 74 to 75 in eb58207

    
           gen_pauli_x = shift(dim) 
        
           gen_pauli_z = clock(dim)

Hmm, so I think these are covered because there is a test for gen_pauli which calls both of these functions. As there isn't any branching in either, testing them via that one function should be all that is required to have them covered from that.

But yes, having a few specific tests for them explicitly might be a good idea, just to be more thorough and explicit.

To close this issue after #478 is merged, in the folder toqito/matrices/tests, add a file labeled test_gen_pauli_x and another labeled test_gen_pauli_z for testing the functions via pytest.

List of all possible tests:

Verify the shape of the matrices is what we expect
Verify the expected output is what we expect for a bunch of different values for dim.

It might also be better to use the parameterized option in pytest to consolidate a bunch of identical tests.
https://docs.pytest.org/en/7.3.x/how-to/parametrize.html

Here's an example test in toqito where pytest verifies an array output.

toqito/toqito/perms/tests/test_antisymmetric_projection.py

Lines 19 to 32 in eb58207

    
           @pytest.mark.parametrize("dim, p_param, partial, expected_result", [ 
        
               # Dimension is 2 and p is equal to 1. 
        
               (2, 1, False, np.array([[1, 0], [0, 1]])), 
        
               # The `p` value is greater than the dimension `d`. 
        
               (2, 3, False, np.zeros((8, 8))), 
        
               # The dimension is 2. 
        
               (2, 2, False, np.array([[0, 0, 0, 0], [0, 0.5, -0.5, 0], [0, -0.5, 0.5, 0], [0, 0, 0, 0]])), 
        
               # The `dim` is 3, the `p` is 3, and `partial` is True. 
        
               (3, 3, True, anti_proj_3_3_partial) 
        
           ]) 
        
           def test_antisymmetric_projection(dim, p_param, partial, expected_result): 
        
               """Test function works as expected for a valid input.""" 
        
               proj = antisymmetric_projection(dim=dim, p_param=p_param, partial=partial).todense() 
        
               assert abs(proj - expected_result).all() <= 1E-3

	@pytest.mark.parametrize("dim, p_param, partial, expected_result", [
	# Dimension is 2 and p is equal to 1.
	(2, 1, False, np.array([[1, 0], [0, 1]])),
	# The `p` value is greater than the dimension `d`.
	(2, 3, False, np.zeros((8, 8))),
	# The dimension is 2.
	(2, 2, False, np.array([[0, 0, 0, 0], [0, 0.5, -0.5, 0], [0, -0.5, 0.5, 0], [0, 0, 0, 0]])),
	# The `dim` is 3, the `p` is 3, and `partial` is True.
	(3, 3, True, anti_proj_3_3_partial)
	])
	def test_antisymmetric_projection(dim, p_param, partial, expected_result):
	"""Test function works as expected for a valid input."""
	proj = antisymmetric_projection(dim=dim, p_param=p_param, partial=partial).todense()
	assert abs(proj - expected_result).all() <= 1E-3