Test symengine on travis (#146)

* test: run symengine tests on travis

* test: fix symengine matrix and properly indent .travis.yml

* test: fix indentation error in .travis.yml

* chore: check variable name type for symengine

* test: raise an exception on travis if symengine could not be used

* fix: add some pickle magic

Tell pickle how to pickle variables

.travis.yml

@@ -1,11 +1,17 @@
 language: python
 sudo: false
 python:
-- '2.7'
-- '3.4'
-- '3.5'
+  - '2.7'
+  - '3.4'
+  - '3.5'
+env:
+  global:
+    - secure: PBcwrLg4ZwVi9Gw25Q2adNd0uK+NCqFSiYl+ZuumkEXs4NQBbSXVd719wrWKUFdIqBy+h9ETo4Vsz/QsTZzI2mSG4zqTkm+oUxMW1tJxYEeKZvCo7GfZ883VlKFgdqvh6iouEvHSjfGbwc5cUp98CbjgI5ni01vGpDQh2hgokkI=
+  matrix:
+    - OPTLANG_USE_SYMENGINE=False
+    - OPTLANG_USE_SYMENGINE=True
 cache:
-- pip: true
+  - pip: true
 addons:
   apt:
     packages:
@@ -16,49 +22,46 @@ addons:
     - glpk-utils
     - pandoc
 before_install:
-- export SYMPY_USE_CACHE=no
-- export OPTLANG_USE_SYMENGINE=no
-- pip install pip --upgrade
-- 'echo "this is a build for: $TRAVIS_BRANCH"'
-- 'if [[ "$TRAVIS_PYTHON_VERSION" != "3.5" ]]; then bash ./.travis/install_cplex.sh; fi'
+  - export SYMPY_USE_CACHE=no
+  - pip install pip --upgrade
+  - 'echo "this is a build for: $TRAVIS_BRANCH"'
+  - 'if [[ "$TRAVIS_PYTHON_VERSION" != "3.5" ]]; then bash ./.travis/install_cplex.sh; fi'
 install:
-- pip install nose nose-progressive rednose coverage docutils flake8 codecov jsonschema
-- pip install -r requirements.txt
-- pip install inspyred
-- pip install pypandoc
-- pip install swiglpk
-- pip install scipy
-- python setup.py install
+  - pip install nose nose-progressive rednose coverage docutils flake8 codecov jsonschema
+  - pip install -r requirements.txt
+  - pip install inspyred
+  - pip install pypandoc
+  - pip install swiglpk
+  - pip install scipy
+  - pip install symengine
+  - python setup.py install
 before_script:
-- flake8 .
+  - flake8 .
 script: nosetests
 after_success:
-- codecov
+  - codecov
 notifications:
   slack:
     secure: s8Dj0MFreNwZ3Zhb0+5yJiHPL33JsxLjmoRo8f0ohLdD15L//E4VjkCsYkNEcLzid6HarEL/1JSmzAuGl40fCdLqTAoDRy01shT1zmfWQPXQlaALh5f8ExBAlyDHxKhd/B2SytYu6uhe0WOuxu/oo4c33a7pKhuV1piNcevPZew=
 before_deploy:
-- pip install twine
-- python setup.py sdist bdist_wheel
-env:
-  global:
-  - secure: PBcwrLg4ZwVi9Gw25Q2adNd0uK+NCqFSiYl+ZuumkEXs4NQBbSXVd719wrWKUFdIqBy+h9ETo4Vsz/QsTZzI2mSG4zqTkm+oUxMW1tJxYEeKZvCo7GfZ883VlKFgdqvh6iouEvHSjfGbwc5cUp98CbjgI5ni01vGpDQh2hgokkI=
+  - pip install twine
+  - python setup.py sdist bdist_wheel
 deploy:
-- provider: releases
-  api_key:
-    secure: u4aJv+5YoH3gjJpyiVoq33SqKIUtx8LWPp15pIh8hKHmUgJNyjGm7ELXOeczfQ5W7ZpnWj+ogewaes2oA0NLxBB1/MBPL7kr77hmzp+XhZomh73DzFKegbpBTgqpioBRxvPlq3HYNIWqrLkeg/HYlBW1WM6mKifFUwqbIaL+++4=
-  file_glob: true
-  file: dist/optlang*.whl
-  skip_cleanup: true
-  on:
-    branch: master
-    tags: true
-    repo: biosustain/optlang
-- provider: pypi
-  user: Nikolaus.Sonnenschein
-  password:
-    secure: Gn23MUvzP1DPJXxRXUOXGBJjyMamawxey5ByrOd+JT90roljHKSk8v1wdBMH7+s1DB/ygUJqB2Zy0cBC3mr0waY6HmxKpXhddgzQzG56Eua/npTxpz58Y8xfSYF+5QqS3gcyBrYEXmeHWuEURERy0b7uYKMx/QcHAHYhTaVy4zE=
-  on:
-    branch: master
-    tags: true
-    repo: biosustain/optlang
+  - provider: releases
+    api_key:
+      secure: u4aJv+5YoH3gjJpyiVoq33SqKIUtx8LWPp15pIh8hKHmUgJNyjGm7ELXOeczfQ5W7ZpnWj+ogewaes2oA0NLxBB1/MBPL7kr77hmzp+XhZomh73DzFKegbpBTgqpioBRxvPlq3HYNIWqrLkeg/HYlBW1WM6mKifFUwqbIaL+++4=
+    file_glob: true
+    file: dist/optlang*.whl
+    skip_cleanup: true
+    on:
+      branch: master
+      tags: true
+      repo: biosustain/optlang
+  - provider: pypi
+    user: Nikolaus.Sonnenschein
+    password:
+      secure: Gn23MUvzP1DPJXxRXUOXGBJjyMamawxey5ByrOd+JT90roljHKSk8v1wdBMH7+s1DB/ygUJqB2Zy0cBC3mr0waY6HmxKpXhddgzQzG56Eua/npTxpz58Y8xfSYF+5QqS3gcyBrYEXmeHWuEURERy0b7uYKMx/QcHAHYhTaVy4zE=
+    on:
+      branch: master
+      tags: true
+      repo: biosustain/optlang

optlang/interface.py

@@ -304,6 +304,9 @@ def __getstate__(self):
     def __setstate__(self, state):
         self.__dict__ = state
 
+    def __reduce__(self):
+        return (type(self), (self.name, self.lb, self.ub, self.type, self.problem))
+
     def to_json(self):
         """
         Returns a json-compatible object from the Variable that can be saved using the json module.

optlang/symbolics.py

@@ -40,6 +40,8 @@
     except ImportError as e:
         if SYMENGINE_PREFERENCE.lower() in ("true", "yes", "on"):
             logger.warn("Symengine could not be imported: " + str(e))
+            if os.getenv('TRAVIS', None) is not None:  # Travis should error here # pragma: no cover
+                raise RuntimeError("Symengine should be used but could not be!")
         USE_SYMENGINE = False
     else:
         USE_SYMENGINE = True
@@ -68,6 +70,9 @@
 
     class Symbol(symengine_Symbol):
         def __new__(cls, name, *args, **kwargs):
+            if not isinstance(name, six.string_types):
+                raise TypeError("name should be a string, not %s" % repr(type(name)))
+
             return symengine_Symbol.__new__(cls, name)
 
         def __init__(self, name, *args, **kwargs):