test-expr: add tests to Expr order
test-expr: add tests to Expr order

trying to find the cause of different output on travis:
https://travis-ci.org/rudymatela/speculate/jobs/216412180

for speculate-reason.model-test:

-complete (complete t) == complete t
- normalize emptyThy e == e
-              okThy t == True
-     equivalent t e e == True
-     equivalent t e f == equivalent t f e
+    normalize emptyThy e == e
+normalize (complete t) e == normalize t e
+   complete (complete t) == complete t
+                 okThy t == True
+        equivalent t e e == True
+        equivalent t e f == equivalent t f e

rudymatela/speculate