Allow for customization of the environment in which test fixtures are…

… initialized. (#9894)

core/dbt/tests/fixtures/project.py

@@ -1,5 +1,7 @@
 import os
 from pathlib import Path
+from typing import Mapping
+
 import pytest  # type: ignore
 import random
 from argparse import Namespace
@@ -493,11 +495,18 @@ def get_tables_in_schema(self):
         return {model_name: materialization for (model_name, materialization) in result}
 
 
+@pytest.fixture(scope="class")
+def environment() -> Mapping[str, str]:
+    # By default, fixture initialization is done with the following environment
+    # from the os, but this fixture provides a way to customize the environment.
+    return os.environ
+
+
 # Housekeeping that needs to be done before we start setting up any test fixtures.
 @pytest.fixture(scope="class")
-def initialization() -> None:
+def initialization(environment) -> None:
     # Create an "invocation context," which dbt application code relies on.
-    set_invocation_context(os.environ)
+    set_invocation_context(environment)
 
     # Enable caches used between test runs, for better testing performance.
     enable_test_caching()

tests/functional/partial_parsing/test_pp_vars.py

@@ -264,11 +264,16 @@ def test_env_vars_models(self, project):
 
 
 class TestProjectEnvVars:
+    @pytest.fixture(scope="class")
+    def environment(self):
+        custom_env = os.environ.copy()
+        custom_env["ENV_VAR_NAME"] = "Jane Smith"
+        return custom_env
+
     @pytest.fixture(scope="class")
     def project_config_update(self):
         # Need to set the environment variable here initially because
         # the project fixture loads the config.
-        os.environ["ENV_VAR_NAME"] = "Jane Smith"
         return {"models": {"+meta": {"meta_name": "{{ env_var('ENV_VAR_NAME') }}"}}}
 
     @pytest.fixture(scope="class")
@@ -279,6 +284,7 @@ def models(self):
 
     def test_project_env_vars(self, project):
         # Initial run
+        os.environ["ENV_VAR_NAME"] = "Jane Smith"
         results = run_dbt(["run"])
         assert len(results) == 1
         manifest = get_manifest(project.project_root)
@@ -308,13 +314,14 @@ def models(self):
             "model_one.sql": model_one_sql,
         }
 
+    @pytest.fixture(scope="class")
+    def environment(self):
+        custom_env = os.environ.copy()
+        custom_env["ENV_VAR_HOST"] = "localhost"
+        return custom_env
+
     @pytest.fixture(scope="class")
     def dbt_profile_target(self):
-        # Need to set these here because the base integration test class
-        # calls 'load_config' before the tests are run.
-        # Note: only the specified profile is rendered, so there's no
-        # point it setting env_vars in non-used profiles.
-        os.environ["ENV_VAR_HOST"] = "localhost"
         return {
             "type": "postgres",
             "threads": 4,