Stop using platform_admin_client fixture

We have a `client_request` fixture which does a bunch of useful stuff
like:
- checking the status code of the response
- returning a `BeautifulSoup` object

For most tests of a platform admin view we used `platform_admin_client`
instead. This is not as good because it returns a raw `Response` object
and doesn’t do the additional checks.

This commit converts all the tests using `platform_admin_client` to:
use new `client_request` and log in as `platform_admin_user` before
making any requests.

This is also nice because it makes any test easy to parametrize with
additional users, for example to test differences in behaviour dependant
on being platform admin or not.

tests/conftest.py

@@ -2768,19 +2768,6 @@ def logged_in_client_with_session(
     yield client
 
 
-@pytest.fixture(scope='function')
-def platform_admin_client(
-    client,
-    platform_admin_user,
-    mocker,
-    service_one,
-    mock_login,
-):
-    mocker.patch('app.user_api_client.get_user', return_value=platform_admin_user)
-    client.login(platform_admin_user, mocker, service_one)
-    yield client
-
-
 @pytest.fixture
 def os_environ():
     """
@@ -2821,6 +2808,7 @@ def client_request(logged_in_client, mocker, service_one):  # noqa (C901 too com
             _test_page_title=True,
             _test_for_elements_without_class=True,
             _optional_args="",
+            _raw_response=False,
             **endpoint_kwargs
         ):
             return ClientRequest.get_url(
@@ -2830,6 +2818,7 @@ def client_request(logged_in_client, mocker, service_one):  # noqa (C901 too com
                 _expected_redirect=_expected_redirect,
                 _test_page_title=_test_page_title,
                 _test_for_elements_without_class=_test_for_elements_without_class,
+                _raw_response=_raw_response,
             )
 
         @staticmethod
@@ -2840,6 +2829,7 @@ def client_request(logged_in_client, mocker, service_one):  # noqa (C901 too com
             _expected_redirect=None,
             _test_page_title=True,
             _test_for_elements_without_class=True,
+            _raw_response=False,
             **endpoint_kwargs
         ):
             resp = logged_in_client.get(
@@ -2854,6 +2844,10 @@ def client_request(logged_in_client, mocker, service_one):  # noqa (C901 too com
 
             if _expected_redirect:
                 assert resp.location == _expected_redirect
+
+            if _raw_response:
+                return resp
+
             page = BeautifulSoup(resp.data.decode('utf-8'), 'html.parser')
             if _test_page_title:
                 count_of_h1s = len(page.select('h1'))
@@ -2890,18 +2884,26 @@ def client_request(logged_in_client, mocker, service_one):  # noqa (C901 too com
             _expected_status=None,
             _follow_redirects=False,
             _expected_redirect=None,
+            _raw_response=False,
+            _content_type=None,
             **endpoint_kwargs
         ):
             if _expected_status is None:
                 _expected_status = 200 if _follow_redirects else 302
+            post_kwargs = {}
+            if _content_type:
+                post_kwargs.update(content_type=_content_type)
             resp = logged_in_client.post(
                 url_for(endpoint, **(endpoint_kwargs or {})),
                 data=_data,
                 follow_redirects=_follow_redirects,
+                **post_kwargs
             )
             assert resp.status_code == _expected_status
             if _expected_redirect:
                 assert_url_expected(resp.location, _expected_redirect)
+            if _raw_response:
+                return resp
             return BeautifulSoup(resp.data.decode('utf-8'), 'html.parser')
 
         @staticmethod