Make duckdb the standard in the dev-env environment

MetricFlow's testing configuration currently tags sql engine types
to hatch execution environment. The standard one, which we use for
`make test`, is meant to be duckdb, but a stale environment variable
can cause inscrutable failures on any test requiring an engine
connection.

This change updates the test environment configuration to make duckdb
the standard for any runs in the hatch dev-env, including any
invocation such as `make test`. It also removes the default fallback
to duckdb, which was causing inconsistent behaviors in certain
environment configurations, and replaces it with a consistent error.

Developers with heavily customized environment configurations might
have a bad time with this, but they were already having a bad time
with other things, and at least this gives them an actionable
error message.

.changes/unreleased/Under the Hood-20230814-225729.yaml

@@ -0,0 +1,6 @@
+kind: Under the Hood
+body: Make duckdb the standard for all dev-env environment runs, including `make test`
+time: 2023-08-14T22:57:29.775028-07:00
+custom:
+  Author: tlento
+  Issue: "723"

metricflow/test/fixtures/setup_fixtures.py

@@ -2,6 +2,7 @@
 
 import datetime
 import logging
+import os
 import warnings
 from dataclasses import dataclass
 
@@ -68,24 +69,18 @@ def pytest_addoption(parser: _pytest.config.argparsing.Parser) -> None:
     )
 
 
-class MetricFlowTestEnvironmentVariables:
-    """Environment variables to setup the testing environment."""
-
-    MF_SQL_ENGINE_URL = EnvironmentVariable("MF_SQL_ENGINE_URL")
-    MF_SQL_ENGINE_PASSWORD = EnvironmentVariable("MF_SQL_ENGINE_PASSWORD")
-
-
 @pytest.fixture(scope="session")
 def mf_test_session_state(  # noqa: D
     request: FixtureRequest,
     disable_sql_alchemy_deprecation_warning: None,
     source_table_snapshot_repository: SqlTableSnapshotRepository,
 ) -> MetricFlowTestSessionState:
-    engine_url = MetricFlowTestEnvironmentVariables.MF_SQL_ENGINE_URL.get_optional()
-    if engine_url is None:
-        logger.info(f"{MetricFlowTestEnvironmentVariables.MF_SQL_ENGINE_URL.name} has not been set, so using DuckDb")
-        engine_url = "duckdb://"
-    engine_password = MetricFlowTestEnvironmentVariables.MF_SQL_ENGINE_PASSWORD.get_optional() or ""
+    engine_url = os.environ.get("MF_SQL_ENGINE_URL")
+    assert engine_url is not None, (
+        "MF_SQL_ENGINE_URL environment variable has not been set! Are you running in a properly configured "
+        "environment? Check out our CONTRIBUTING.md for pointers to our environment configurations."
+    )
+    engine_password = os.environ.get("MF_SQL_ENGINE_PASSWORD", "")
 
     current_time = datetime.datetime.now().strftime("%Y_%m_%d")
     random_suffix = random_id()

pyproject.toml

@@ -118,6 +118,7 @@ features = [
 
 [tool.hatch.envs.dev-env.env-vars]
 	MF_TEST_ADAPTER_TYPE="duckdb"
+  MF_SQL_ENGINE_URL="duckdb://"
 
 [tool.hatch.envs.postgres-env.env-vars]
 	MF_SQL_ENGINE_URL="postgresql://metricflow@localhost:5432/metricflow"