OpenCypher Tests¶

The tests validate OpenCypher query support, common graph patterns, and recent path-mode semantics.

They also include regression coverage for planner behavior that matters to the Python bindings, such as UNWIND variables being usable inside WHERE predicates.

OpenCypher¶

OpenCypher is a declarative graph query language for pattern matching and traversal.

import arcadedb_embedded as arcadedb

with arcadedb.create_database("./opencypher_test_db") as db:
    db.command("sql", "CREATE VERTEX TYPE Person")
    db.command("sql", "CREATE EDGE TYPE Knows")

    with db.transaction():
        alice = db.new_vertex("Person")
        alice.set("name", "Alice").save()

        bob = db.new_vertex("Person")
        bob.set("name", "Bob").save()

        edge = alice.new_edge("Knows", bob)
        edge.save()

    result = db.query("opencypher", """
        MATCH (p:Person)-[:Knows]->(friend:Person)
        RETURN friend.name as name
    """)

    names = [r.get("name") for r in result]
    assert "Bob" in names

Running This Test¶

pytest tests/test_cypher.py -v

Notable Regression Coverage¶

Path modes: default TRAIL, explicit ACYCLIC, and WALK
WALK requires an explicit hop bound on cyclic traversals
UNWIND variables can be referenced from WHERE clauses during MATCH
Aggregations on missing labels still return a single row with 0
Result property order remains stable for projected OpenCypher values

Path Mode Example¶

MATCH ACYCLIC (a:Node {name: 'A'})-[:LINK*1..5]->(b)
RETURN b.name AS name

This coverage is intentionally test-focused: Python already reaches these features through db.query("opencypher", ...), so the bindings need semantic verification more than a dedicated wrapper API.

OpenCypher vs SQL MATCH¶

Feature	SQL MATCH	OpenCypher
Style	SQL-like	Declarative graph patterns
Focus	Set operations + graph patterns	Pattern matching + paths
Learning curve	Easier if you know SQL	Easier if you know Cypher
Graph traversal	Strong	Strong

Example Comparison¶

SQL MATCH:

MATCH {type: Person, as: p}-Knows->{type: Person, as: friend}
RETURN friend.name

OpenCypher:

MATCH (p:Person)-[:Knows]->(friend:Person)
RETURN friend.name