Remove low quality FunctionGraph test relying on stale pickle data

This test simply loaded an old example of pickled data. It was both extremely indirect and brittle. Changes to the code base will eventually invalidate nearly all of the old classes used, and whatever the exact issue was, it should've been tested directly.

Remove low quality FunctionGraph test relying on stale pickle data
af703ed2 · Brandon T. Willard · 21daf4e0 · af703ed2 · 21daf4e0
--- a/tests/gof/test_fg.py
+++ b/tests/gof/test_fg.py
-import os
 import pickle

-import pytest
-
-import theano
-from theano.compat import PY3
-from theano.gof.fg import FunctionGraph
 from theano import tensor as tt
+from theano.gof.fg import FunctionGraph


 class TestFunctionGraph:
@@ -16,24 +11,3 @@ class TestFunctionGraph:

        s = pickle.dumps(func)
        pickle.loads(s)
-
-    @pytest.mark.skipif(
-        not theano.config.cxx, reason="G++ not available, so we need to skip this test."
-    )
-    @pytest.mark.slow
-    def test_node_outputs_not_used(self):
-        # In the past, we where removing some not used variable from
-        # fgraph.variables event if the apply had other output used in
-        # the graph. This caused a crash.
-        # This test run the pickle that reproduce this case.
-        with open(
-            os.path.join(os.path.dirname(__file__), "test_fg_old_crash.pkl"), "rb"
-        ) as f:
-            from theano.misc.pkl_utils import CompatUnpickler
-
-            if PY3:
-                u = CompatUnpickler(f, encoding="latin1")
-            else:
-                u = CompatUnpickler(f)
-            d = u.load()
-        f = theano.function(**d)
--- a/tests/gof/test_fg_old_crash.pkl
+++ b/tests/gof/test_fg_old_crash.pkl