lint: Warn users that CYLC_VERSION={{CYLC_VERSION}} is deprecated (#5890)

* Cylc Lint to warn users that CYLC_VERSION={{CYLC_VERSION}} is deprecated.
Additional warnings for ROSE_VERSION and FCM_VERSION in the same manner.

* Fix check which was returning false positives
Made the test for presence of lint messages optionally count those messages.

* fix-flake8

* fix

* Fixed merge

* correction

* Update cylc/flow/scripts/lint.py

Co-authored-by: Oliver Sanders <[email protected]>

---------

Co-authored-by: Oliver Sanders <[email protected]>

Author: wxtim

changes.d/5890.feat.md

@@ -0,0 +1,2 @@
+Lint: Warn users that setting ``CYLC_VERSION``, ``ROSE_VERSION`` or
+``FCM_VERSION`` in the workflow config is deprecated.

cylc/flow/scripts/lint.py

@@ -320,6 +320,27 @@ def check_indentation(line: str) -> bool:
     return bool(len(match[0]) % 4 != 0)
 
 
+CHECK_FOR_OLD_VARS = re.compile(
+    r'CYLC_VERSION\s*=\s*\{\{\s*CYLC_VERSION\s*\}\}'
+    r'|ROSE_VERSION\s*=\s*\{\{\s*ROSE_VERSION\s*\}\}'
+    r'|FCM_VERSION\s*=\s*\{\{\s*FCM_VERSION\s*\}\}'
+)
+
+
+def list_wrapper(line: str, check: Callable) -> Optional[Dict[str, str]]:
+    """Take a line and a check function and return a Dict if there is a
+    result, None otherwise.
+
+    Returns
+
+        Dict, in for {'vars': Error string}
+    """
+    result = check(line)
+    if result:
+        return {'vars': '\n    * '.join(result)}
+    return None
+
+
 FUNCTION = 'function'
 
 STYLE_GUIDE = (
@@ -655,7 +676,20 @@ def check_indentation(line: str) -> bool:
             'writing-workflows/runtime.html#task-event-template-variables'
         ),
         FUNCTION: check_for_deprecated_task_event_template_vars,
-    }
+    },
+    'U016': {
+        'short': 'Deprecated template vars: {vars}',
+        'rst': (
+            'It is no longer necessary to configure the environment variables '
+            '``CYLC_VERSION``, ``ROSE_VERSION`` or ``FCM_VERSION``.'
+        ),
+        'url': (
+            'https://cylc.github.io/cylc-doc/stable/html/plugins/'
+            'cylc-rose.html#special-variables'
+        ),
+        FUNCTION: functools.partial(
+            list_wrapper, check=CHECK_FOR_OLD_VARS.findall),
+    },
 }
 RULESETS = ['728', 'style', 'all']
 EXTRA_TOML_VALIDATION = {

tests/unit/scripts/test_lint.py

@@ -96,6 +96,12 @@
             graph = MyFaM:finish-all => remote => !mash_theme
 
 [runtime]
+    [[root]]
+        [[[environment]]]
+            CYLC_VERSION={{CYLC_VERSION}}
+            ROSE_VERSION  = {{ROSE_VERSION     }}
+            FCM_VERSION = {{   FCM_VERSION   }}
+
     [[MyFaM]]
         extra log files = True
         {% from 'cylc.flow' import LOG %}
@@ -151,7 +157,6 @@
  [scheduler]
 
 [[dependencies]]
-
 {% set   N = 009 %}
 {% foo %}
 {{foo}}
@@ -206,13 +211,22 @@ def filter_strings(items, contains):
     ]
 
 
-def assert_contains(items, contains):
+def assert_contains(items, contains, instances=None):
     """Pass if at least one item contains a given string."""
-    if not filter_strings(items, contains):
+    filtered = filter_strings(items, contains)
+    if not filtered:
         raise Exception(
             f'Could not find: "{contains}" in:\n'
-            + pformat(items)
-        )
+            + pformat(items))
+    elif instances and len(filtered) != instances:
+        raise Exception(
+            f'Expected "{contains}" to appear {instances} times'
+            f', got it {len(filtered)} times.')
+
+
+EXPECT_INSTANCES_OF_ERR = {
+    16: 3,
+}
 
 
 @pytest.mark.parametrize(
@@ -222,7 +236,8 @@ def assert_contains(items, contains):
 def test_check_cylc_file_7to8(number):
     """TEST File has one of each manual deprecation;"""
     lint = lint_text(TEST_FILE, ['728'])
-    assert_contains(lint.messages, f'[U{number:03d}]')
+    instances = EXPECT_INSTANCES_OF_ERR.get(number, None)
+    assert_contains(lint.messages, f'[U{number:03d}]', instances)
 
 
 def test_check_cylc_file_7to8_has_shebang():