code: def test_at_min(self, xp, dtype):
      shape = (50,)
      x = testing.shaped_random(shape, xp=xp, dtype=dtype, seed=0)
      mask = testing.shaped_random(shape, xp=xp, dtype=bool, seed=1)
      indices = xp.nonzero(mask)[0]
      xp.minimum.at(x, indices, 3)
      return x
  
imports: import numpy
  import pytest
  import cupy
  from cupy import testing
label_desc: Use image node_id 5 for calling the TestUfuncAtAtomicOps obj's underlying member method code with example usage: obj.test_at_min(xp, dtype) and returns: x