diff --git a/hook.py b/hook.py
index 105e34f..48d273f 100644
--- a/hook.py
+++ b/hook.py
@@ -13,7 +13,6 @@
 
 async def enable(services):
     atomic_gui = AtomicGUI(services, name, description)
-    app = services.get('app_svc').application
 
     # we only ingest data once, and save new abilities in the data/ folder of the plugin
     if "abilities" not in os.listdir(data_dir):
diff --git a/scripts/check_coverage.py b/scripts/check_coverage.py
new file mode 100644
index 0000000..58cca7c
--- /dev/null
+++ b/scripts/check_coverage.py
@@ -0,0 +1,29 @@
+#!/usr/bin/env python3
+"""Run coverage combine/xml/report only when coverage data files exist.
+
+Used by the coverage-ci tox environment to avoid a "No data to combine"
+failure when upstream test environments did not produce any coverage data.
+"""
+import glob
+import subprocess
+import sys
+
+
+def main():
+    files = glob.glob('.coverage.*')
+    if not files:
+        print('No coverage data files found, skipping combine')
+        return
+
+    for cmd in [['coverage', 'combine'], ['coverage', 'xml'], ['coverage', 'report']]:
+        result = subprocess.run(cmd)
+        if result.returncode != 0:
+            print(
+                f'Command {" ".join(cmd)!r} failed with exit code {result.returncode}',
+                file=sys.stderr,
+            )
+            sys.exit(result.returncode)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tests/test_hook.py b/tests/test_hook.py
index f23c090..34d6c79 100644
--- a/tests/test_hook.py
+++ b/tests/test_hook.py
@@ -1,6 +1,6 @@
 import os
 import pytest
-from unittest.mock import MagicMock, AsyncMock, patch, PropertyMock
+from unittest.mock import MagicMock, AsyncMock, patch
 
 
 class TestHookModuleAttributes:
@@ -103,23 +103,3 @@ async def test_enable_skips_ingest_when_abilities_exist(self):
             # AtomicService should NOT be instantiated when abilities dir exists
             mock_svc_cls.assert_not_called()
 
-    @pytest.mark.asyncio
-    async def test_enable_accesses_app(self):
-        """enable() should access services['app_svc'].application."""
-        import hook
-
-        mock_app = MagicMock()
-        mock_app_svc = MagicMock()
-        type(mock_app_svc).application = PropertyMock(return_value=mock_app)
-
-        services = {
-            'auth_svc': MagicMock(),
-            'data_svc': MagicMock(),
-            'app_svc': mock_app_svc,
-        }
-
-        with patch.object(hook, 'data_dir', '/tmp/atomic_test_hook_data'), \
-             patch('os.listdir', return_value=['abilities']), \
-             patch('hook.AtomicGUI'):
-            await hook.enable(services)
-            type(mock_app_svc).application.assert_called()
diff --git a/tox.ini b/tox.ini
index ce5c3be..38257e9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -26,17 +26,17 @@ deps =
     pytest-aiohttp
     coverage
     codecov
-changedir = {homedir}/tmp
+changedir = {env:HOME}/tmp
 commands =
-	/usr/bin/git clone https://github.com/mitre/caldera.git --recursive {homedir}/tmp
-	/bin/rm -rf {homedir}/tmp/plugins/atomic
-	python -m pip install -r {homedir}/tmp/requirements.txt
-	/usr/bin/cp -R {toxinidir} {homedir}/tmp/plugins/atomic
-    coverage run -p -m pytest --tb=short --rootdir={homedir}/tmp -Werror plugins/atomic/tests
+	git clone https://github.com/mitre/caldera.git --recursive {env:HOME}/tmp
+	rm -rf {env:HOME}/tmp/plugins/atomic
+	python -m pip install -r {env:HOME}/tmp/requirements.txt
+	cp -R {toxinidir} {env:HOME}/tmp/plugins/atomic
+    coverage run -p -m pytest --tb=short --rootdir={env:HOME}/tmp -Werror plugins/atomic/tests
 allowlist_externals =
-	/usr/bin/sudo *
-	/usr/bin/git *
-	/usr/bin/cp *
+    git
+    rm
+    cp
 
 [testenv:py38]
 description = run tests
@@ -47,23 +47,23 @@ deps =
     pytest-aiohttp
     coverage
     codecov
-changedir = {homedir}/tmp
+changedir = {env:HOME}/tmp
 commands =
-	/usr/bin/git clone https://github.com/mitre/caldera.git --recursive {homedir}/tmp
-	/bin/rm -rf {homedir}/tmp/plugins/atomic
-	python -m pip install -r {homedir}/tmp/requirements.txt
-	/usr/bin/cp -R {toxinidir} {homedir}/tmp/plugins/atomic
-    coverage run -p -m pytest --tb=short --rootdir={homedir}/tmp {homedir}/tmp/plugins/atomic/tests
+	git clone https://github.com/mitre/caldera.git --recursive {env:HOME}/tmp
+	rm -rf {env:HOME}/tmp/plugins/atomic
+	python -m pip install -r {env:HOME}/tmp/requirements.txt
+	cp -R {toxinidir} {env:HOME}/tmp/plugins/atomic
+    coverage run -p -m pytest --tb=short --rootdir={env:HOME}/tmp {env:HOME}/tmp/plugins/atomic/tests
 allowlist_externals =
-	/usr/bin/sudo *
-	/usr/bin/git *
-	/usr/bin/cp *
+    git
+    rm
+    cp
 
 [testenv:coverage]
 deps =
     coverage
 skip_install = true
-changedir = {homedir}/tmp
+changedir = {env:HOME}/tmp
 commands =
     coverage combine
     coverage html
@@ -74,8 +74,6 @@ deps =
     coveralls
     coverage
 skip_install = true
-changedir = {homedir}/tmp
+changedir = {env:HOME}/tmp
 commands =
-    coverage combine
-    coverage xml
-    coverage report
+    python {toxinidir}/scripts/check_coverage.py