class_docstr: Unit tests for the ``constant`` function.
class_docstr_tok: ["Unit","tests","for","the","``","constant","``","function","."]
docstr: Test that the ``constant`` convenience function returns a callable with two arguments
  corresponding to the trainable parameters and time.
docstr_tok: ["Test","that","the","``","constant","``","convenience","function","returns","a","callable","with","two","arguments","corresponding","to","the","trainable","parameters","and","time","."]
code: def test_constant_signature(self):
      """Test that the ``constant`` convenience function returns a callable with two arguments
      corresponding to the trainable parameters and time."""
      argspec = inspect.getfullargspec(qml.pulse.constant)
  
      assert callable(qml.pulse.constant)
      assert argspec.args == ["scalar", "time"]
  
imports: import inspect
  from functools import reduce
  import numpy
  import pytest
  import pennylane
  from pennylane.pulse import ParametrizedHamiltonian
label_desc: Use image node_id 1 for calling the TestConstant obj's underlying member method code with example usage: obj.test_constant_signature() without return types