tests: more tests for random funcs (#135)

* tests: more tests for random funcs

Author: samir-nasibli

tests/skipped_tests.tbl

@@ -30,6 +30,12 @@ tests/test_random.py::test_random_check_otput[random_sample]
 tests/test_random.py::test_random_check_otput[randf]
 tests/test_random.py::test_random_check_otput[sample]
 tests/test_random.py::test_random_check_otput[rand]
+tests/test_random.py::test_randn_normal_distribution
+tests/test_random.py::test_radnom_seed[random]
+tests/test_random.py::test_radnom_seed[random_sample]
+tests/test_random.py::test_radnom_seed[randf]
+tests/test_random.py::test_radnom_seed[sample]
+tests/test_random.py::test_radnom_seed[rand]
 tests/third_party/cupy/binary_tests/test_elementwise.py::TestElementwise::test_bitwise_and
 tests/third_party/cupy/binary_tests/test_elementwise.py::TestElementwise::test_bitwise_or
 tests/third_party/cupy/binary_tests/test_elementwise.py::TestElementwise::test_bitwise_xor

tests/test_random.py

@@ -2,7 +2,8 @@
 
 import dpnp.random
 import numpy
-
+# from scipy import stats
+from numpy.testing import assert_allclose
 
 @pytest.mark.parametrize("func",
                          [dpnp.random.rand,
@@ -49,3 +50,48 @@ def test_random_check_otput(func):
     for i in range(res.size):
         assert res[i] >= 0.0
         assert res[i] < 1.0
+
+
+def test_randn_normal_distribution():
+    """ Check if the sample obtained from the dpnp.random.randn differs from
+    the normal distribution.
+    Using ``scipy.stats.normaltest``.
+
+    It is based on D’Agostino and Pearson’s test that combines skew
+    and kurtosis to produce an omnibus test of normality,
+    see: https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.normaltest.html
+    """
+    pts = 1000
+    alpha = 0.05
+    dpnp.random.seed(28041990)
+    x = dpnp.random.randn(pts)
+    _, p = stats.normaltest(x)
+    # null hypothesis: x comes from a normal distribution.
+    # The p-value is interpreted against an alpha of 5% and finds that the test
+    # dataset does not significantly deviate from normal.
+    # If p > alpha, the null hypothesis cannot be rejected.
+    assert p > alpha
+
+
+@pytest.mark.parametrize("func",
+                         [dpnp.random.random,
+                          dpnp.random.random_sample,
+                          dpnp.random.randf,
+                          dpnp.random.sample,
+                          dpnp.random.rand],
+                         ids=['random', 'random_sample',
+                              'randf', 'sample',
+                              'rand'])
+def test_radnom_seed(func):
+    seed = 28041990
+    size = 100
+    shape = (100, 1)
+    if func in [dpnp.random.rand, dpnp.random.randn]:
+        args = size
+    else:
+        args = shape
+    dpnp.random.seed(seed)
+    a1 = func(args)
+    dpnp.random.seed(seed)
+    a2 = func(args)
+    assert_allclose(a1, a2, rtol=1e-07, atol=0)