Remove EnvironmentVariable helper class

This class is doing a whole lot to accomplish very little. In
updating the sql engine url environment variable access I noticed
the old EnvironmentVariable helper was hardly being used at all
anymore. Since most of its usage has disappeared into the sands
of time, we remove the last remaining calls - and the class
itself - here.

metricflow/test/fixtures/setup_fixtures.py

@@ -12,7 +12,6 @@
 from _pytest.fixtures import FixtureRequest
 from sqlalchemy.engine import make_url
 
-from metricflow.configuration.env_var import EnvironmentVariable
 from metricflow.random_id import random_id
 from metricflow.test.fixtures.sql_clients.common_client import SqlDialect
 from metricflow.test.table_snapshot.table_snapshots import SqlTableSnapshotHash, SqlTableSnapshotRepository
@@ -154,8 +153,15 @@ def warn_user_about_slow_tests_without_parallelism(  # noqa: D
     request: FixtureRequest,
     mf_test_session_state: MetricFlowTestSessionState,
 ) -> None:
-    worker_count_env_var = EnvironmentVariable("PYTEST_XDIST_WORKER_COUNT", "1")
-    num_workers = worker_count_env_var.get_int()
+    worker_count_env_var = os.environ.get("PYTEST_XDIST_WORKER_COUNT", "1")
+    try:
+        num_workers = int(worker_count_env_var)
+    except ValueError as e:
+        raise ValueError(
+            f"Could not convert environment variable PYTEST_XDIST_WORKER_COUNT to int! "
+            f"Value in environ was: {worker_count_env_var}"
+        ) from e
+
     num_items = len(request.session.items)
     dialect = dialect_from_url(mf_test_session_state.sql_engine_url)
 

metricflow/test/generate_snapshots.py

@@ -43,7 +43,6 @@
 from dbt_semantic_interfaces.implementations.base import FrozenBaseModel
 from dbt_semantic_interfaces.pretty_print import pformat_big_objects
 
-from metricflow.configuration.env_var import EnvironmentVariable
 from metricflow.protocols.sql_client import SqlEngine
 
 logger = logging.getLogger(__name__)
@@ -162,15 +161,14 @@ def run_cli() -> None:  # noqa: D
     dev_format = "%(asctime)s %(levelname)s %(filename)s:%(lineno)d [%(threadName)s] - %(message)s"
     logging.basicConfig(level=logging.INFO, format=dev_format)
 
-    credential_sets_json_env_var = EnvironmentVariable("MF_TEST_ENGINE_CREDENTIAL_SETS")
-    if credential_sets_json_env_var.get_optional() is None:
+    credential_sets_json_str = os.environ.get("MF_TEST_ENGINE_CREDENTIAL_SETS")
+    if credential_sets_json_str is None:
         raise ValueError(
-            f"Environment variable: {credential_sets_json_env_var.name} has not been set. Please see the comment in "
+            f"Environment variable: MF_TEST_ENGINE_CREDENTIAL_SETS has not been set. Please see the comment in "
             f"{__file__} for details on how to set it."
         )
 
-    credentials_sets_json_str = credential_sets_json_env_var.get()
-    credential_sets = MetricFlowTestCredentialSetForAllEngines.parse_raw(credentials_sets_json_str)
+    credential_sets = MetricFlowTestCredentialSetForAllEngines.parse_raw(credential_sets_json_str)
 
     logger.info(
         f"Running the following tests to generate snapshots:\n{pformat_big_objects(SNAPSHOT_GENERATING_TEST_FILES)}"