Unify tests for digraph and multidigraph

[jackboyla]

Me again 😇 I parameterised all unit tests so they run for DiGraph and MultiDiGraph.

Doing this I spotted a bug in my implementation for WHERE clauses for MultiDiGraphs. It's now fixed 😄.

Here's an example of it working. Previously it was returning empty results.

from grandcypher import GrandCypher
import networkx as nx

host = nx.MultiDiGraph()
host.add_node("a", name="Alice", age=25)
host.add_node("b", name="Bob", age=30)
host.add_node("c", name="Christine", age=30)
host.add_edge("a", "b", __labels__={"friend"}, years=1, friendly="very")
host.add_edge("b", "a", __labels__={"colleague"}, years=2)
host.add_edge("b", "a", __labels__={"mentor"}, years=4)
host.add_edge("b", "c", __labels__={"chef"}, years=12)

qry = """
MATCH (n)-[r]->(m)
WHERE n.name == "Alice"
RETURN n.name, m.name, r.__labels__, r.years, r.friendly
"""
res = GrandCypher(host).run(qry)
print(res)

# {
#      'n.name': ['Alice'], 
#      'm.name': ['Bob'], 
#      'r.__labels__': [{0: {'friend'}}], 
#      'r.years': [{0: 1}], 
#      'r.friendly': [{0: 'very'}]
# }

[j6k4m8]

wooo! nice bugfix, and great addition to the test suite!!