test: add 'nodb' test runner

ensure things work as expected if sqlalchemy is not installed

tests/test_conf.py

@@ -5,12 +5,10 @@ import os
 from unittest import TestCase
 from unittest.mock import patch, MagicMock
 
-import sqlalchemy as sa
+import pytest
 
 from wuttjamaican import conf
 from wuttjamaican.exc import ConfigurationError
-from wuttjamaican.db import Session
-from wuttjamaican.db.conf import make_engine_from_config
 from wuttjamaican.app import AppHandler
 from wuttjamaican.testing import FileConfigTestCase
 
@@ -133,6 +131,13 @@ require = %(here)s/first.conf
         self.assertEqual(config.get('foo'), 'bar')
 
     def test_constructor_db_flags(self):
+        try:
+            # nb. we don't need this import but the test will not
+            # behave correctly unless the lib is installed
+            import sqlalchemy
+        except ImportError:
+            pytest.skip("test is not relevant without sqlalchemy")
+
         myfile = self.write_file('my.conf', """\
 [wutta.config]
 usedb = true
@@ -155,6 +160,12 @@ preferdb = true
         self.assertTrue(config.preferdb)
 
     def test_constructor_db_not_supported(self):
+        try:
+            # nb. we don't need this import but the test will not
+            # behave correctly unless the lib is installed
+            import sqlalchemy
+        except ImportError:
+            pytest.skip("test is not relevant without sqlalchemy")
 
         # flags are off by default
         config = conf.WuttaConfig()
@@ -269,6 +280,12 @@ configure_logging = true
         self.assertEqual(config.get('foo', default='bar'), 'bar')
 
     def test_get_from_db(self):
+        try:
+            import sqlalchemy as sa
+            from wuttjamaican.db import Session
+        except ImportError:
+            pytest.skip("test is not relevant without sqlalchemy")
+
         # minimal config, but at least it needs db cxn info
         config = conf.WuttaConfig(defaults={'wutta.db.default.url': 'sqlite://'})
 
@@ -317,6 +334,11 @@ configure_logging = true
             self.assertIn("makin stuff up", str(error))
 
     def test_get_preferdb(self):
+        try:
+            import sqlalchemy as sa
+            from wuttjamaican.db import Session
+        except ImportError:
+            pytest.skip("test is not relevant without sqlalchemy")
 
         # start out with a default value
         config = conf.WuttaConfig(defaults={'wutta.db.default.url': 'sqlite://',
@@ -403,6 +425,10 @@ configure_logging = true
         self.assertIsInstance(app, CustomAppHandler)
 
     def test_get_engine_maker(self):
+        try:
+            from wuttjamaican.db.conf import make_engine_from_config
+        except ImportError:
+            pytest.skip("test is not relevant without sqlalchemy")
 
         # default func
         config = conf.WuttaConfig()
@@ -421,7 +447,7 @@ class CustomAppHandler(AppHandler):
     pass
 
 
-def custom_make_engine_from_config(*args, **kwargs):
+def custom_make_engine_from_config():
     pass