feat: add aggregations.py

Signed-off-by: Charles Larivier <charles@dribbble.com>

Author: Charles Larivier

src/metabase/mbql/aggregations.py

@@ -1,32 +1,52 @@
+from typing import List
+
 from metabase.mbql.base import Mbql
 
 
 class Aggregation(Mbql):
-    mbql: str
+    function: str
 
-    def compile(self):
-        return [self.mbql]
+    def compile(self) -> List:
+        return [self.function, super(Aggregation, self).compile()]
 
 
-class ColumnAggregation(Aggregation):
-    def __init__(self, field_id: int):
-        self.field_id = field_id
+class Count(Aggregation):
+    function = "count"
 
-    def compile(self):
-        return [self.mbql, ["field", self.field_id, None]]
+    def __init__(self, id: int = None):
+        self.id = id
 
+    def compile(self) -> List:
+        return [self.function]
 
-class Count(Aggregation):
-    mbql = "count"
+
+class Sum(Aggregation):
+    function = "sum"
+
+
+class Average(Aggregation):
+    function = "avg"
+
+
+class Distinct(Aggregation):
+    function = "distinct"
+
+
+class CumulativeSum(Aggregation):
+    function = "cum-sum"
+
+
+class CumulativeCount(Aggregation):
+    function = "cum-count"
 
 
-class Sum(ColumnAggregation):
-    mbql = "sum"
+class StandardDeviation(Aggregation):
+    function = "stddev"
 
 
-class Max(ColumnAggregation):
-    mbql = "max"
+class Min(Aggregation):
+    function = "min"
 
 
-class Min(ColumnAggregation):
-    mbql = "min"
+class Max(Aggregation):
+    function = "max"

tests/mbql/test_aggregations.py

@@ -0,0 +1,25 @@
+from unittest import TestCase
+
+from metabase.mbql.aggregations import Aggregation, Count
+
+
+class AggregationTests(TestCase):
+    def test_aggregation(self):
+        """Ensure Aggregation.compile() returns [self.function, ['field', self.id, self.option']]."""
+
+        class Mock(Aggregation):
+            function = "mock"
+
+        aggregation = Mock(id=2)
+        self.assertEqual(["mock", ["field", 2, None]], aggregation.compile())
+
+        aggregation = Mock(id=2, option={"foo": "bar"})
+        self.assertEqual(["mock", ["field", 2, {"foo": "bar"}]], aggregation.compile())
+
+    def test_count(self):
+        """Ensure Count optionally accepts an id attribute."""
+        count = Count()
+        self.assertEqual(["count"], count.compile())
+
+        count = Count(id=5)
+        self.assertEqual(["count"], count.compile())