skip expiredocs test for redis version below 7.2 (#4275)

we skip this test for Redis versions below 7.2 due to a bug in PEXPIRE.
In older versions, a bug involving multiple time samplings during PEXPIRE execution can cause keys to prematurely expire, triggering a "del" notification and eliminating them from the index, thus missing from search results.
This impacts the test as the key should be included in the search results but return NULL upon access (i.e lazy expiration).
The bug was resolved in Redis 7.2, ensuring the test's stability.

(cherry picked from commit 3afdc42)

Co-authored-by: meiravgri <meirav.grimberg@redis.com>

tests/pytests/test_expire.py

@@ -55,13 +55,13 @@ def add_explain_to_results(results):
     for offset, i in enumerate(range(2, len(results), 2)):
         results.insert(i+offset, res_score_and_explanation)
     return results
-                           
+
 def buildExpireDocsResults(isSortable, isJson):
     results = {}
     # When calling FT.SEARCH with SORTBY on json index, the sortby field is loaded into the result together with the json document
     results[both_docs_no_sortby] = [2, 'doc1', ['t', 'bar'], 'doc2', ['t', 'foo']] if not isJson else [2, 'doc1', ['$', '{"t":"bar"}'], 'doc2', ['$', '{"t":"foo"}']]
     results[both_docs_sortby] = [2, 'doc1', ['t', 'bar'], 'doc2', ['t', 'foo']] if not isJson else [2, 'doc1', ['t', 'bar','$', '{"t":"bar"}'], 'doc2', ['t', 'foo', '$', '{"t":"foo"}']]
- 
+
     results[doc1_is_empty] = [2, 'doc1', [], 'doc2', ['t', 'foo']] if not isJson else [2, 'doc1', [], 'doc2', ['$', '{"t":"foo"}']]
     results[doc1_is_empty_sortby] = [2, 'doc2', ['t', 'foo'], 'doc1', []] if not isJson else [2, 'doc2', ['t', 'foo', '$', '{"t":"foo"}'], 'doc1', []]
 
@@ -87,15 +87,17 @@ def buildExpireDocsResults(isSortable, isJson):
     #         empty_with_scores_and_explain_last if not isSortable else partial_with_scores_and_explain,
     #         empty_with_scores_and_explain_last if not isSortable else partial_with_scores_and_explain_last]
 
-@skip(cluster=True)
+# Refer to expireDocs for details on why this test is skipped for Redis versions below 7.2
+@skip(cluster=True, redis_less_than="7.2")
 def testExpireDocs(env):
 
     for isJson in [False, True]:
         expected_results = buildExpireDocsResults(False, isJson)
         expireDocs(env, False, # Without SORTABLE - since the fields are not SORTABLE, we need to load the results from Redis Keyspace
                 expected_results, isJson)
 
-@skip(cluster=True)
+# Refer to expireDocs for details on why this test is skipped for Redis versions below 7.2
+@skip(cluster=True, redis_less_than="7.2")
 def testExpireDocsSortable(env):
     '''
     Same as test `testExpireDocs` only with SORTABLE
@@ -111,6 +113,13 @@ def testExpireDocsSortable(env):
 
 
 #TODO: DvirDu: I think this test should be broken down to smaller tests, due to the complexity of the test and the number of cases it covers it is hard to debug
+# Skip this test for Redis versions below 7.2 due to a bug in PEXPIRE.
+# In older versions, a bug involving multiple time samplings during PEXPIRE execution
+# can cause keys to prematurely expire, triggering a "del" notification and eliminating them from the index,
+# thus missing from search results.
+# This impacts the test as the key should be included in the search results but return NULL upon access
+# (i.e lazy expiration).
+# The bug was resolved in Redis 7.2, ensuring the test's stability.
 def expireDocs(env, isSortable, expected_results, isJson):
     '''
     This test creates an index and two documents
@@ -174,7 +183,7 @@ def expireDocs(env, isSortable, expected_results, isJson):
         if isJson:
             conn.execute_command('JSON.SET', 'doc1', '$', '{"t":"bar"}')
             conn.execute_command('JSON.SET', 'doc2', '$', '{"t":"foo"}')
-        else: 
+        else:
             conn.execute_command('HSET', 'doc1', 't', 'bar')
             conn.execute_command('HSET', 'doc2', 't', 'foo')