Allow to count number of entries of an aggregation

reframe/frontend/reporting/utility.py

@@ -17,7 +17,7 @@ class Aggregation:
 
     AGG_REGEX = re.compile(r'(?P<op>\S+)\((?P<col>\S+)\)|(?P<op2>\S+)')
     OP_REGEX = re.compile(
-        r'min|max|median|mean|std|first|last|sum|stats|p\d{2}'
+        r'min|max|median|mean|std|first|last|sum|stats|count|p\d{2}'
     )
     Q_REGEX = re.compile(r'p(\d{2})')
 
@@ -89,6 +89,8 @@ def _expr_from_op(col, op):
                 return pl.col(col).last().alias(f'{col} (last)')
             elif op == 'sum':
                 return pl.col(col).sum().alias(f'{col} (sum)')
+            elif op == 'count':
+                return pl.col(col).count().alias(f'{col} (count)')
             elif m := self.Q_REGEX.match(op):
                 perc = m.group(1)
                 if perc == '00':

unittests/test_reporting.py

@@ -228,7 +228,8 @@ def test_parse_cmp_spec_period(time_period):
 
 @pytest.fixture(params=['first', 'last', 'mean', 'median',
                         'min', 'max', 'std', 'stats', 'sum',
-                        'p00', 'p01', 'p05', 'p95', 'p99'])
+                        'p00', 'p01', 'p05', 'p95', 'p99',
+                        'count'])
 def aggregator(request):
     return request.param
 
@@ -289,6 +290,8 @@ def test_parse_cmp_spec_aggregations(aggregator):
         assert agg['pval (p95)'][0] == 10
     elif aggregator == 'p05':
         assert agg['pval (p99)'][0] == 10
+    elif aggregator == 'count':
+        assert 'pval (count)' in agg.columns
 
     # Check variant without base period
     match = parse_cmp_spec(f'now-1d:now/{aggregator}:/')