TST: create_diagonal: add test from SciPy

Co-authored-by: Jake Bowhay <[email protected]>

Author: lucascolley

tests/test_funcs.py

@@ -6,6 +6,7 @@
 
 # array-api-strict#6
 import array_api_strict as xp  # type: ignore[import-untyped]
+import numpy as np
 import pytest
 from numpy.testing import assert_allclose, assert_array_equal, assert_equal
 
@@ -114,6 +115,7 @@ def test_combination(self):
 
 class TestCreateDiagonal:
     def test_1d(self):
+        # from np.diag tests
         vals = 100 * xp.arange(5, dtype=xp.float64)
         b = xp.zeros((5, 5))
         for k in range(5):
@@ -127,13 +129,24 @@ def test_1d(self):
         assert_array_equal(create_diagonal(vals, offset=2, xp=xp), b)
         assert_array_equal(create_diagonal(vals, offset=-2, xp=xp), c)
 
+    @pytest.mark.parametrize("n", range(1, 10))
+    @pytest.mark.parametrize("offset", range(1, 10))
+    def test_create_diagonal(self, n, offset):
+        # from scipy._lib tests
+        rng = np.random.default_rng(2347823)
+        one = xp.asarray(1.0)
+        x = rng.random(n)
+        A = create_diagonal(xp.asarray(x, dtype=one.dtype), offset=offset, xp=xp)
+        B = xp.asarray(np.diag(x, offset), dtype=one.dtype)
+        assert_array_equal(A, B)
+
     def test_0d(self):
         with pytest.raises(ValueError, match="1-dimensional"):
-            print(create_diagonal(xp.asarray(1), xp=xp))
+            create_diagonal(xp.asarray(1), xp=xp)
 
     def test_2d(self):
         with pytest.raises(ValueError, match="1-dimensional"):
-            print(create_diagonal(xp.asarray([[1]]), xp=xp))
+            create_diagonal(xp.asarray([[1]]), xp=xp)
 
 
 class TestKron: