code: def setUp(self):
      self.dtype = numpy.dtype(self.dtype)
      n = self.n
      nrhs = 1 if self.nrhs is None else self.nrhs
      # Diagonally dominant matrix is used as it is stable
      alpha = 2.0 / n
      a = self._make_matrix((n, n), alpha, -alpha / 2)
      diag = cupy.diag(cupy.ones((n,), dtype=self.dtype.char.lower()))
      a[diag > 0] = 0
      a += diag
      x = self._make_matrix((n, nrhs), 0.2, 0.9)
      b = cupy.matmul(a, x)
      b_shape = [n]
      if self.nrhs is not None:
          b_shape.append(nrhs)
      b = b.reshape(b_shape)
      self.a = a
      if self.nrhs is None or self.nrhs == 1:
          self.b = b.copy(order=self.order)
      else:
          self.b = b.copy(order="F")
      self.x_ref = x.reshape(b_shape)
      self.tol = self._tol[self.dtype.char.lower()]
  
imports: import unittest
  import numpy
  import pytest
  import cupy
  from cupy import testing
  import cupyx
  from cupyx import cusolver, lapack
label_desc: Use image node_id 3 for calling the TestGesv obj's underlying member method code with example usage: obj.setUp() without return types