text: import pytest
  
  import os
  
  import numpy as np
  from numpy.testing import (
      assert_, assert_equal, assert_array_equal, assert_array_almost_equal,
      assert_raises, _assert_valid_refcount,
      )
  
  
  class TestRegression:
      def test_poly1d(self):
          # Ticket #28
          assert_equal(np.poly1d([1]) - np.poly1d([1, 0]),
                       np.poly1d([-1, 1]))
  
      def test_cov_parameters(self):
          # Ticket #91
          x = np.random.random((3, 3))
          y = x.copy()
          np.cov(x, rowvar=True)
          np.cov(y, rowvar=False)
          assert_array_equal(x, y)
  
      def test_mem_digitize(self):
          # Ticket #95
          for i in range(100):
              np.digitize([1, 2, 3, 4], [1, 3])
              np.digitize([0, 1, 2, 3, 4], [1, 3])
  
      def test_unique_zero_sized(self):
          # Ticket #205
          assert_array_equal([], np.unique(np.array([])))
  
      def test_mem_vectorise(self):
          # Ticket #325
          vt = np.vectorize(lambda *args: args)
          vt(np.zeros((1, 2, 1)), np.zeros((2, 1, 1)), np.zeros((1, 1, 2)))
          vt(np.zeros((1, 2, 1)), np.zeros((2, 1, 1)), np.zeros((1,
             1, 2)), np.zeros((2, 2)))
  
      def test_mgrid_single_element(self):
          # Ticket #339
          assert_array_equal(np.mgrid[0:0:1j], [0])
          assert_array_equal(np.mgrid[0:0], [])
  
      def test_refcount_vectorize(self):
          # Ticket #378
          def p(x, y):
              return 123
          v = np.vectorize(p)
          _assert_valid_refcount(v)
  
      def test_poly1d_nan_roots(self):
          # Ticket #396
          p = np.poly1d([np.nan, np.nan, 1], r=False)
          assert_raises(np.linalg.LinAlgError, getattr, p, "r")
  
      def test_mem_polymul(self):
          # Ticket #448
          np.polymul([], [1.])
  
      def test_mem_string_concat(self):
          # Ticket #469
          x = np.array([])
          np.append(x, 'asdasd\tasdasd')
  
      def test_poly_div(self):
          # Ticket #553
          u = np.poly1d([1, 2, 3])
          v = np.poly1d([1, 2, 3, 4, 5])
          q, r = np.polydiv(u, v)
          assert_equal(q*v + r, u)
  
      def test_poly_eq(self):
          # Ticket #554
          x = np.poly1d([1, 2, 3])
          y = np.poly1d([3, 4])
          assert_(x != y)
          assert_(x == x)
  
      def test_polyfit_build(self):
          # Ticket #628
          ref = [-1.06123820e-06, 5.70886914e-04, -1.13822012e-01,
                 9.95368241e+00, -3.14526520e+02]
          x = [90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103,
               104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115,
               116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 129,
               130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141,
               146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157,
               158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169,
               170, 171, 172, 173, 174, 175, 176]
          y = [9.0, 3.0, 7.0, 4.0, 4.0, 8.0, 6.0, 11.0, 9.0, 8.0, 11.0, 5.0,
               6.0, 5.0, 9.0, 8.0, 6.0, 10.0, 6.0, 10.0, 7.0, 6.0, 6.0, 6.0,
               13.0, 4.0, 9.0, 11.0, 4.0, 5.0, 8.0, 5.0, 7.0, 7.0, 6.0, 12.0,
               7.0, 7.0, 9.0, 4.0, 12.0, 6.0, 6.0, 4.0, 3.0, 9.0, 8.0, 8.0,
               6.0, 7.0, 9.0, 10.0, 6.0, 8.0, 4.0, 7.0, 7.0, 10.0, 8.0, 8.0,
               6.0, 3.0, 8.0, 4.0, 5.0, 7.0, 8.0, 6.0, 6.0, 4.0, 12.0, 9.0,
               8.0, 8.0, 8.0, 6.0, 7.0, 4.0, 4.0, 5.0, 7.0]
          tested = np.polyfit(x, y, 4)
          assert_array_almost_equal(ref, tested)
  
      def test_polydiv_type(self):
          # Make polydiv work for complex types
          msg = "Wrong type, should be complex"
          x = np.ones(3, dtype=complex)
          q, r = np.polydiv(x, x)
          assert_(q.dtype == complex, msg)
          msg = "Wrong type, should be float"
          x = np.ones(3, dtype=int)
          q, r = np.polydiv(x, x)
          assert_(q.dtype == float, msg)
  
      def test_histogramdd_too_many_bins(self):
          # Ticket 928.
          assert_raises(ValueError, np.histogramdd, np.ones((1, 10)), bins=2**10)
  
      def test_polyint_type(self):
          # Ticket #944
          msg = "Wrong type, should be complex"
          x = np.ones(3, dtype=complex)
          assert_(np.polyint(x).dtype == complex, msg)
          msg = "Wrong type, should be float"
          x = np.ones(3, dtype=int)
          assert_(np.polyint(x).dtype == float, msg)
  
      def test_ndenumerate_crash(self):
          # Ticket 1140
          # Shouldn't crash:
          list(np.ndenumerate(np.array([[]])))
  
      def test_asfarray_none(self):
          # Test for changeset r5065
          assert_array_equal(np.array([np.nan]), np.asfarray([None]))
  
      def test_large_fancy_indexing(self):
          # Large enough to fail on 64-bit.
          nbits = np.dtype(np.intp).itemsize * 8
          thesize = int((2**nbits)**(1.0/5.0)+1)
  
          def dp():
              n = 3
              a = np.ones((n,)*5)
              i = np.random.randint(0, n, size=thesize)
              a[np.ix_(i, i, i, i, i)] = 0
  
          def dp2():
              n = 3
              a = np.ones((n,)*5)
              i = np.random.randint(0, n, size=thesize)
              a[np.ix_(i, i, i, i, i)]
  
          assert_raises(ValueError, dp)
          assert_raises(ValueError, dp2)
  
      def test_void_coercion(self):
          dt = np.dtype([('a', 'f4'), ('b', 'i4')])
          x = np.zeros((1,), dt)
          assert_(np.r_[x, x].dtype == dt)
  
      def test_who_with_0dim_array(self):
          # ticket #1243
          import os
          import sys
  
          oldstdout = sys.stdout
          sys.stdout = open(os.devnull, 'w')
          try:
              try:
                  np.who({'foo': np.array(1)})
              except Exception:
                  raise AssertionError("ticket #1243")
          finally:
              sys.stdout.close()
              sys.stdout = oldstdout
  
      def test_include_dirs(self):
          # As a sanity check, just test that get_include
          # includes something reasonable.  Somewhat
          # related to ticket #1405.
          include_dirs = [np.get_include()]
          for path in include_dirs:
              assert_(isinstance(path, str))
              assert_(path != '')
  
      def test_polyder_return_type(self):
          # Ticket #1249
          assert_(isinstance(np.polyder(np.poly1d([1]), 0), np.poly1d))
          assert_(isinstance(np.polyder([1], 0), np.ndarray))
          assert_(isinstance(np.polyder(np.poly1d([1]), 1), np.poly1d))
          assert_(isinstance(np.polyder([1], 1), np.ndarray))
  
      def test_append_fields_dtype_list(self):
          # Ticket #1676
          from numpy.lib.recfunctions import append_fields
  
          base = np.array([1, 2, 3], dtype=np.int32)
          names = ['a', 'b', 'c']
          data = np.eye(3).astype(np.int32)
          dlist = [np.float64, np.int32, np.int32]
          try:
              append_fields(base, names, data, dlist)
          except Exception:
              raise AssertionError()
  
      def test_loadtxt_fields_subarrays(self):
          # For ticket #1936
          from io import StringIO
  
          dt = [("a", 'u1', 2), ("b", 'u1', 2)]
          x = np.loadtxt(StringIO("0 1 2 3"), dtype=dt)
          assert_equal(x, np.array([((0, 1), (2, 3))], dtype=dt))
  
          dt = [("a", [("a", 'u1', (1, 3)), ("b", 'u1')])]
          x = np.loadtxt(StringIO("0 1 2 3"), dtype=dt)
          assert_equal(x, np.array([(((0, 1, 2), 3),)], dtype=dt))
  
          dt = [("a", 'u1', (2, 2))]
          x = np.loadtxt(StringIO("0 1 2 3"), dtype=dt)
          assert_equal(x, np.array([(((0, 1), (2, 3)),)], dtype=dt))
  
          dt = [("a", 'u1', (2, 3, 2))]
          x = np.loadtxt(StringIO("0 1 2 3 4 5 6 7 8 9 10 11"), dtype=dt)
          data = [((((0, 1), (2, 3), (4, 5)), ((6, 7), (8, 9), (10, 11))),)]
          assert_equal(x, np.array(data, dtype=dt))
  
      def test_nansum_with_boolean(self):
          # gh-2978
          a = np.zeros(2, dtype=bool)
          try:
              np.nansum(a)
          except Exception:
              raise AssertionError()
  
      def test_py3_compat(self):
          # gh-2561
          # Test if the oldstyle class test is bypassed in python3
          class C():
              """Old-style class in python2, normal class in python3"""
              pass
  
          out = open(os.devnull, 'w')
          try:
              np.info(C(), output=out)
          except AttributeError:
              raise AssertionError()
          finally:
              out.close()
  