Make autocomplete work after pin and negation operators (#10207)

Author: lukaszsamson

lib/iex/lib/iex/autocomplete.ex

@@ -181,6 +181,8 @@ defmodule IEx.Autocomplete do
     |> Enum.reverse()
     |> trim_leading(?&)
     |> trim_leading(?%)
+    |> trim_leading(?!)
+    |> trim_leading(?^)
   end
 
   defp trim_leading([char | rest], char), do: rest

lib/iex/test/iex/autocomplete_test.exs

@@ -312,6 +312,15 @@ defmodule IEx.AutocompleteTest do
     assert expand('f = &Enum.a') == {:yes, [], functions_list}
   end
 
+  test "negation operator completion" do
+    assert expand('!is_bin') == {:yes, 'ary', []}
+  end
+
+  test "pin operator completion" do
+    eval("my_variable = 2")
+    assert expand('^my_va') == {:yes, 'riable', []}
+  end
+
   defmodule SublevelTest.LevelA.LevelB do
   end