raise when trying to count a source (#127)

Author: greg-rychlewski

lib/ecto/adapters/sqlite3/connection.ex

@@ -1375,6 +1375,12 @@ defmodule Ecto.Adapters.SQLite3.Connection do
 
   def expr({:count, _, []}, _sources, _query), do: "count(*)"
 
+  def expr({:count, _, [{:&, _, [_]}]}, _sources, query) do
+    raise Ecto.QueryError,
+      query: query,
+      message: "The argument to `count/1` must be a column in SQLite3"
+  end
+
   def expr({:json_extract_path, _, [expr, path]}, sources, query) do
     path =
       Enum.map(path, fn

test/ecto/adapters/sqlite3/connection/aggregates_test.exs

@@ -15,6 +15,19 @@ defmodule Ecto.Adapters.SQLite3.Connection.AggregatesTest do
     assert ~s{SELECT count(s0."x") FROM "schema" AS s0} == all(query)
   end
 
+  test "raises when counting a source" do
+    query =
+      Schema
+      |> select([r], count(r))
+      |> plan()
+
+    msg = ~r"The argument to `count/1` must be a column in SQLite3"
+
+    assert_raise Ecto.QueryError, msg, fn ->
+      all(query)
+    end
+  end
+
   test "raises when trying to distinct count" do
     assert_raise Ecto.QueryError, fn ->
       Schema