class_docstr: Tests the main functions in the library.
code: def setUp(self):
      super().setUp()
      # Score matrices are of the form num_runs x num_tasks
      self._x = np.array([[1, 2], [2, 2], [1, 1], [2, 1]])
      self._y = np.array([[1, 1], [2, 2], [3, 3]])
  
imports: from absl.testing import absltest
  import numpy
  import rliable.metrics
label_desc: Use image node_id 1 for calling the MetricsTest obj's underlying member method code with example usage: obj.setUp() without return types