Add exception and warning for a.helio.MaxRecords (#7540)

* add error and warning for a.helio.MaxRecords

* reduce warn_user condition code

* add exception test for test_client_search

* add changelog

* Update sunpy/net/helio/hec.py

Co-authored-by: Nabil Freij <nabil.freij@gmail.com>

* match the message in pytest.raise

* make warn_user simpler

* add test for warn_user

* pre-commit changes

* fix changelog reference target

* add test_client_search_limit

* fix pre-commit

* add test_client_search_warning

* remove test_client_search_warning

* pre-commit

* add exception for MaxRecords class

* reduce test_client_search_limit

* reduced matched message

* change test name

* remove unnecessary import

* fix CI

---------

Co-authored-by: Nabil Freij <nabil.freij@gmail.com>

changelog/7540.bugfix.rst

@@ -0,0 +1 @@
+The maximum records in `~sunpy.net.helio.HECClient` now are 20000.

sunpy/net/helio/attrs.py

@@ -12,6 +12,10 @@ class MaxRecords(SimpleAttr):
     """
     The maximum number of desired records.
     """
+    def __init__(self, value):
+        super().__init__(value)
+        if self.value > 20000:
+            raise ValueError("Helio will only return a max of 20000 results.")
 
 
 class TableName(SimpleAttr):

sunpy/net/helio/hec.py

@@ -173,8 +173,8 @@ def search(self, *args, **kwargs):
                                                     MAXRECORDS=max_records)
         results = votable_handler(etree.tostring(results))
         table = HECResponse(results.to_table(), client=self)
-        if len(table) == max_records == 500:
-            warn_user("Number of results is the same as the default `max_records` of 500. "
+        if len(table) == max_records:
+            warn_user("Number of results is the same as current limit. "
                       "It is possible your query has been truncated. "
                       "If you want to change this, set `a.helio.MaxRecords` to a higher value.")
         return table

sunpy/net/helio/tests/test_helio.py

@@ -13,6 +13,7 @@
     webservice_parser,
     wsdl_retriever,
 )
+from sunpy.util.exceptions import SunpyUserWarning
 
 # Currently helio makes unverified requests - this filter should be removed when
 # https://github.com/sunpy/sunpy/issues/4401 is fixed
@@ -290,16 +291,22 @@ def test_client_search(client):
     start = '2005/01/03'
     end = '2005/12/03'
     table_name = 'rhessi_hxr_flare'
-    res = client.search(a.Time(start, end), a.helio.TableName(table_name), a.helio.MaxRecords(10))
+    with pytest.warns(SunpyUserWarning, match="Number of results is the same as current limit. "):
+        res = client.search(a.Time(start, end), a.helio.TableName(table_name), a.helio.MaxRecords(10))
     assert len(res) == 10
 
 
+def test_max_records_limit():
+    with pytest.raises(ValueError, match="Helio will only return a max of 20000 results."):
+        a.helio.MaxRecords(99999)
+
+
 @pytest.mark.remote_data
 def test_HECResponse_iter(client):
     start = '2005/01/03'
     end = '2005/12/03'
     table_name = 'rhessi_hxr_flare'
-    res = client.search(a.Time(start, end), a.helio.TableName(table_name), a.helio.MaxRecords(10))
+    res = client.search(a.Time(start, end), a.helio.TableName(table_name), a.helio.MaxRecords(10000))
     for i in res:
         # Just to make sure iter still works, check number of columns
         assert len(i) == 13