test refactor: update simplest plugin tests

With this refactor, the simplest plugin stops interfering with other
tests.

integration-tests/plugins/simplest/tljh_simplest.py

@@ -1,55 +1,47 @@
 """
-Simplest plugin that exercises all the hooks
+Simplest plugin that exercises all the hooks defined in tljh/hooks.py.
 """
 from tljh.hooks import hookimpl
 
 
 @hookimpl
 def tljh_extra_user_conda_packages():
-    return [
-        "hypothesis",
-    ]
+    return ["tqdm"]
 
 
 @hookimpl
 def tljh_extra_user_pip_packages():
-    return [
-        "django",
-    ]
+    return ["django"]
 
 
 @hookimpl
 def tljh_extra_hub_pip_packages():
-    return [
-        "there",
-    ]
+    return ["there"]
 
 
 @hookimpl
 def tljh_extra_apt_packages():
-    return [
-        "sl",
-    ]
-
-
-@hookimpl
-def tljh_config_post_install(config):
-    # Put an arbitrary marker we can test for
-    config["simplest_plugin"] = {"present": True}
+    return ["sl"]
 
 
 @hookimpl
 def tljh_custom_jupyterhub_config(c):
-    c.JupyterHub.authenticator_class = "tmpauthenticator.TmpAuthenticator"
+    c.Test.jupyterhub_config_set_by_simplest_plugin = True
+
+
+@hookimpl
+def tljh_config_post_install(config):
+    config["Test"] = {"tljh_config_set_by_simplest_plugin": True}
 
 
 @hookimpl
 def tljh_post_install():
-    with open("test_post_install", "w") as f:
-        f.write("123456789")
+    with open("test_tljh_post_install", "w") as f:
+        f.write("file_written_by_simplest_plugin")
 
 
 @hookimpl
 def tljh_new_user_create(username):
     with open("test_new_user_create", "w") as f:
+        f.write("file_written_by_simplest_plugin")
         f.write(username)