docstr: Tests the triangle normal computation.
docstr_tok: ["Tests","the","triangle","normal","computation","."]
code: def test_normal_preset(self, test_inputs, test_outputs):
      """Tests the triangle normal computation."""
      self.assert_output_is_correct(
          triangle.normal, test_inputs, test_outputs
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import numpy
  from six.moves import range
  import tensorflow
  from tensorflow_graphics.geometry.representation import triangle
  from tensorflow_graphics.math import vector
  from tensorflow_graphics.util import test_case
label_desc: Use image node_id 6 for calling the TriangleTest obj's underlying member method code with example usage: obj.test_normal_preset(test_inputs, test_outputs) without return types