Provide explicit reason when client/server tests are skipped

Sometimes it's not missing Safir or httpx but a circular import.

tests/test_query_remote.py

@@ -38,13 +38,16 @@
 
 try:
     from lsst.daf.butler.tests.server import create_test_server
-except ImportError:
+
+    reason_text = ""
+except ImportError as e:
     create_test_server = None
+    reason_text = str(e)
 
 TESTDIR = os.path.abspath(os.path.dirname(__file__))
 
 
-@unittest.skipIf(create_test_server is None, "Server dependencies not installed.")
+@unittest.skipIf(create_test_server is None, f"Server dependencies not installed: {reason_text}")
 class RemoteButlerQueryTests(ButlerQueryTests, unittest.TestCase):
     """Test query system using client/server butler."""
 

tests/test_remote_butler.py

@@ -42,20 +42,28 @@
 try:
     import httpx
     from lsst.daf.butler.remote_butler import ButlerServerError, RemoteButler
-except ImportError:
+
+    remote_butler_import_fail_message = ""
+except ImportError as e:
     # httpx is not available in rubin-env yet, so skip these tests if it's not
     # available
     RemoteButler = None
+    remote_butler_import_fail_message = str(e)
 
 try:
     from lsst.daf.butler.tests.server import create_test_server
-except ImportError:
+
+    server_import_fail_message = ""
+except ImportError as e:
     create_test_server = None
+    server_import_fail_message = str(e)
 
 TESTDIR = os.path.abspath(os.path.dirname(__file__))
 
 
-@unittest.skipIf(RemoteButler is None, "httpx is not installed")
+@unittest.skipIf(
+    RemoteButler is None, f"Remote butler can not be imported: {remote_butler_import_fail_message}"
+)
 class RemoteButlerConfigTests(unittest.TestCase):
     """Test construction of RemoteButler via Butler()"""
 
@@ -64,7 +72,9 @@ def test_bad_config(self):
             Butler({"cls": "lsst.daf.butler.remote_butler.RemoteButler", "remote_butler": {"url": "!"}})
 
 
-@unittest.skipIf(create_test_server is None, "Server dependencies not installed")
+@unittest.skipIf(
+    create_test_server is None, f"Server dependencies not installed: {server_import_fail_message}"
+)
 class RemoteButlerErrorHandlingTests(unittest.TestCase):
     """Test RemoteButler error handling."""
 
@@ -200,7 +210,9 @@ def test_query_projection_drop_postprocessing(self):
         pass
 
 
-@unittest.skipIf(create_test_server is None, "Server dependencies not installed.")
+@unittest.skipIf(
+    create_test_server is None, f"Server dependencies not installed: {server_import_fail_message}"
+)
 class RemoteButlerSqliteRegistryTests(RemoteButlerRegistryTests, unittest.TestCase):
     """Tests for RemoteButler's registry shim, with a SQLite DB backing the
     server.
@@ -209,7 +221,9 @@ class RemoteButlerSqliteRegistryTests(RemoteButlerRegistryTests, unittest.TestCa
     postgres = None
 
 
-@unittest.skipIf(create_test_server is None, "Server dependencies not installed.")
+@unittest.skipIf(
+    create_test_server is None, f"Server dependencies not installed: {server_import_fail_message}"
+)
 class RemoteButlerPostgresRegistryTests(RemoteButlerRegistryTests, unittest.TestCase):
     """Tests for RemoteButler's registry shim, with a Postgres DB backing the
     server.

tests/test_server.py

@@ -41,8 +41,11 @@
     from lsst.daf.butler.remote_butler.server import create_app
     from lsst.daf.butler.remote_butler.server._dependencies import butler_factory_dependency
     from lsst.daf.butler.tests.server import TEST_REPOSITORY_NAME, UnhandledServerError, create_test_server
-except ImportError:
+
+    reason_text = ""
+except ImportError as e:
     create_test_server = None
+    reason_text = str(e)
 
 from unittest.mock import NonCallableMock, patch
 
@@ -66,7 +69,7 @@
 TESTDIR = os.path.abspath(os.path.dirname(__file__))
 
 
-@unittest.skipIf(create_test_server is None, "Server dependencies not installed.")
+@unittest.skipIf(create_test_server is None, f"Server dependencies not installed: {reason_text}")
 class ButlerClientServerTestCase(unittest.TestCase):
     """Test for Butler client/server."""