Add hypothesis tests for data operators.

.gitignore

@@ -43,3 +43,5 @@ benchmark/benchmark_data.js
 *-tasks.txt
 *compiled_coeff*
 result_images/
+
+.hypothesis/

qutip/tests/core/data/test_operators_hypothesis.py

@@ -0,0 +1,83 @@
+import numpy
+
+from hypothesis import given, strategies as st
+
+from qutip.core import data as _data
+from qutip.tests import strategies as qst
+
+
+@given(qst.qobj_np(), qst.qobj_dtypes())
+def test_data_create(np_array, dtype):
+    if len(np_array.shape) == 1:
+        np_array = numpy.atleast_2d(np_array).transpose()
+    else:
+        np_array = numpy.atleast_2d(np_array)
+    data = _data.to(dtype, _data.create(np_array))
+    numpy.testing.assert_allclose(
+        data.to_array(), numpy.atleast_2d(np_array), rtol=1e-15
+    )
+
+
+@given(qst.qobj_datas())
+def test_data_neg_operator(data):
+    neg = -data
+    numpy.testing.assert_allclose(
+        neg.to_array(), -data.to_array(), rtol=1e-15
+    )
+
+
+same_shape = st.shared(qst.qobj_shapes())
+
+@given(qst.qobj_datas(shape=same_shape), qst.qobj_datas(shape=same_shape))
+def test_data_add_operator(a, b):
+    result = a + b
+    numpy.testing.assert_allclose(
+        result.to_array(), a.to_array() + b.to_array(), rtol=1e-15
+    )
+
+
+@given(qst.qobj_datas(shape=same_shape), qst.qobj_datas(shape=same_shape))
+def test_data_minus_operator(a, b):
+    result = a - b
+    numpy.testing.assert_allclose(
+        result.to_array(), a.to_array() - b.to_array(), rtol=1e-15
+    )
+
+
+@given(qst.qobj_datas(shape=same_shape), qst.qobj_datas(shape=same_shape))
+def test_data_matmul_operator(a, b):
+    result = a @ b
+    numpy.testing.assert_allclose(
+        result.to_array(), a.to_array() @ b.to_array(), rtol=1e-15
+    )
+
+
+@given(st.complex_numbers(), qst.qobj_datas(shape=same_shape))
+def test_data_scalar_multiplication_left_operator(x, a):
+    result = x * a
+    numpy.testing.assert_allclose(
+        result.to_array(), x * a.to_array(), rtol=1e-15
+    )
+
+
+@given(qst.qobj_datas(shape=same_shape), st.complex_numbers())
+def test_data_scalar_multiplication_right_operator(a, x):
+    result = a * x
+    numpy.testing.assert_allclose(
+        result.to_array(), a.to_array() * x, rtol=1e-15
+    )
+
+@given(qst.qobj_datas(shape=same_shape), st.complex_numbers())
+def test_data_scalar_division_operator(a, x):
+    result = a / x
+    numpy.testing.assert_allclose(
+        result.to_array(), a.to_array() / x, rtol=1e-15
+    )
+
+
+@given(qst.qobj_datas(shape=same_shape), qst.qobj_datas(shape=same_shape))
+def test_data_equality_operator(a, b):
+    result = (a == b)
+    assert result == numpy.allclose(
+        a.to_array(), b.to_array(), rtol=1e-15
+    )

qutip/tests/strategies.py

@@ -0,0 +1,51 @@
+""" Hypothesis strategies for QuTiP. """
+
+import numpy
+
+from hypothesis import strategies as st
+from hypothesis.extra import numpy as npst
+
+from qutip.core import data as _data
+
+
+def qobj_dtypes():
+    """
+    A strategy for Qobj data-layer dtypes.
+    """
+    dtype_list = sorted(_data.to.dtypes, key=lambda t: t.__name__)
+    return st.sampled_from(dtype_list)
+
+
+def qobj_shapes():
+    """
+    A strategy for Qobj data-layer shapes.
+    """
+    return npst.array_shapes(max_dims=2)
+
+
+def qobj_np(shape=qobj_shapes()):
+    """
+    A strategy for returning Qobj compatible numpy arrays.
+    """
+    return npst.arrays(shape=shape, dtype=numpy.complex128)
+
+
+@st.composite
+def qobj_datas(draw, shape=qobj_shapes(), dtype=qobj_dtypes()):
+    """
+    A strategy for returning Qobj data-layer instances.
+
+    Parameters
+    ----------
+    shape : strategy
+        A strategy to produce the array shapes. Defaults to `qobj_shapes()`.
+    dtype : strategy
+        A strategy to produce the array QuTiP dtypes. Defaults to
+        `qobj_dtypes()`.
+    """
+    # TODO: In future it might be good to have flags like unitary,
+    #       hermitian, ket, dm, oper, etc to restrict the kinds of
+    #       objects produced.
+    dtype = draw(dtype)
+    data = draw(qobj_np(shape=shape))
+    return _data.to(dtype, _data.create(data))

setup.cfg

@@ -52,6 +52,7 @@ semidefinite =
 tests =
     pytest>=5.2
     pytest-rerunfailures
+    hypothesis
 ipython =
     ipython
 ; This uses ConfigParser's string interpolation to include all the above