Travis tests failing

[lumip]

The following tests are suddenly failing on travis across all branches without an apparent change to the tested functionality in question. Problems with sympy dependency?

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ERROR: test_indexing (tests.expression_tests.ExpressionScalarTests)
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Traceback (most recent call last):
  File "/home/travis/build/qutech/qc-toolkit/qctoolkit/expressions.py", line 40, in _parse_evaluate_numeric_arguments
    return {v: eval_args[v] for v in self.variables}
  File "/home/travis/build/qutech/qc-toolkit/qctoolkit/expressions.py", line 40, in <dictcomp>
    return {v: eval_args[v] for v in self.variables}
KeyError: 'a[i]'
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "/home/travis/build/qutech/qc-toolkit/tests/expression_tests.py", line 137, in test_indexing
    self.assertEqual(e.evaluate_numeric(**params), 2 * 2)
  File "/home/travis/build/qutech/qc-toolkit/qctoolkit/expressions.py", line 62, in evaluate_numeric
    parsed_kwargs = self._parse_evaluate_numeric_arguments(kwargs)
  File "/home/travis/build/qutech/qc-toolkit/qctoolkit/expressions.py", line 42, in _parse_evaluate_numeric_arguments
    raise ExpressionVariableMissingException(key_error.args[0], self) from key_error
qctoolkit.expressions.ExpressionVariableMissingException: Could not evaluate <c*a[i]>: A value for variable <a[i]> is missing!
======================================================================
ERROR: test_eval_sum (tests.utils.sympy_tests.EvaluationTests)
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Traceback (most recent call last):
  File "/home/travis/build/qutech/qc-toolkit/tests/utils/sympy_tests.py", line 251, in test_eval_sum
    result = self.evaluate(expr, parameters)
  File "/home/travis/build/qutech/qc-toolkit/tests/utils/sympy_tests.py", line 226, in evaluate
    return evaluate_lambdified(expression, variables=list(variables), parameters=parameters, lambdified=None)[0]
  File "/home/travis/build/qutech/qc-toolkit/qctoolkit/utils/sympy.py", line 189, in evaluate_lambdified
    [{'ceiling': numpy_compatible_ceiling}, 'numpy'])
  File "/home/travis/miniconda3/envs/test-environment/lib/python3.5/site-packages/sympy/utilities/lambdify.py", line 462, in lambdify
    c = compile(funcstr, filename, 'exec')
  File "<lambdifygenerated-466>", line 1
    def _lambdifygenerated(a[i], a):
                            ^
SyntaxError: invalid syntax

[lumip]

This seems to be related with a new version of sympy (1.2) becoming available and being automatically pulled by travis during tests. The issues do not occur with sympy 1.1.1. Current solution is to fix the required sympy version to 1.1.1 in setup.py. However, for the future, these issues should probably be resolved for newer sympy versions (from 1.2 and up).

[terrorfisch]

sympy changed free_symbols bahaviour for sympy.Indexed

sympy/sympy#14899