Support ISO8601 without timezone

lib/machete/matchers/iso8601_datetime_matcher.ex

@@ -5,6 +5,7 @@ defmodule Machete.ISO8601DateTimeMatcher do
 
   import Machete.DateTimeMatcher
   import Machete.Mismatch
+  import Machete.NaiveDateTimeMatcher
   import Machete.Operators
 
   defstruct datetime_opts: nil
@@ -20,6 +21,7 @@ defmodule Machete.ISO8601DateTimeMatcher do
   @type opts :: [
           {:precision, 0..6},
           {:time_zone, Calendar.time_zone() | :utc},
+          {:offset_required, boolean()},
           {:exactly, DateTime.t()},
           {:roughly, DateTime.t() | :now},
           {:before, DateTime.t() | :now},
@@ -34,6 +36,7 @@ defmodule Machete.ISO8601DateTimeMatcher do
   * `precision`: Requires the matched ISO8601 string to have the specified microsecond precision
   * `time_zone`: Requires the matched ISO8601 string to have the specified time zone. The atom
     `:utc` can be used to specify the "Etc/UTC" time zone
+  * `offset_required`: Requires the matched ISO8601 string to have a timezone. Defaults to true
   * `exactly`: Requires the matched ISO8601 string to be exactly equal to the specified DateTime
   * `roughly`: Requires the matched ISO8601 string to be within +/- 10 seconds of the specified 
     DateTime. This values must be specified as a DateTime. The atom `:now` can be used to use the
@@ -65,6 +68,9 @@ defmodule Machete.ISO8601DateTimeMatcher do
       iex> assert DateTime.utc_now() |> DateTime.to_iso8601() ~> iso8601_datetime(roughly: :now)
       true
 
+      iex> assert NaiveDateTime.utc_now() |> NaiveDateTime.to_iso8601() ~> iso8601_datetime(roughly: :now, offset_required: false)
+      true
+
       iex> assert "2020-01-01T00:00:00.000000Z" ~> iso8601_datetime(roughly: ~U[2020-01-01 00:00:05.000000Z])
       true
 
@@ -85,13 +91,34 @@ defmodule Machete.ISO8601DateTimeMatcher do
 
   defimpl Machete.Matchable do
     def mismatches(%@for{} = a, b) when is_binary(b) do
-      DateTime.from_iso8601(b)
-      |> case do
-        {:ok, datetime_b, 0} -> datetime_b ~>> datetime(a.datetime_opts)
-        _ -> mismatch("#{inspect(b)} is not a parseable ISO8601 datetime")
+      with nil <- matches_date_time(b, a.datetime_opts) do
+        matches_naive_date_time(b, a.datetime_opts)
       end
     end
 
     def mismatches(%@for{}, b), do: mismatch("#{inspect(b)} is not a string")
+
+    defp matches_date_time(b, datetime_opts) do
+      case DateTime.from_iso8601(b) do
+        {:ok, datetime_b, 0} -> datetime_b ~>> datetime(datetime_opts)
+        _ -> nil
+      end
+    end
+
+    defp matches_naive_date_time(b, datetime_opts) do
+      {offset_required, datetime_opts} = Keyword.pop(datetime_opts, :offset_required, true)
+
+      case NaiveDateTime.from_iso8601(b) do
+        {:ok, naive_datetime_b} ->
+          if offset_required do
+            mismatch("#{inspect(b)} does not have a time zone offset")
+          else
+            naive_datetime_b ~>> naive_datetime(datetime_opts)
+          end
+
+        _ ->
+          mismatch("#{inspect(b)} is not a parseable ISO8601 datetime")
+      end
+    end
   end
 end

test/machete/matchers/iso8601_datetime_matcher_test.exs

@@ -28,6 +28,18 @@ defmodule ISO8601DateTimeMatcherTest do
            )
   end
 
+  test "does not supports ISO8601 without timezones by default" do
+    assert "2020-01-01T00:00:00.000000"
+           ~>> iso8601_datetime(roughly: ~N[2020-01-01 00:00:00])
+           ~> mismatch("\"2020-01-01T00:00:00.000000\" does not have a time zone offset")
+  end
+
+  test "supports ISO8601 without timezones" do
+    assert "2020-01-01T00:00:00.000000"
+           ~>> iso8601_datetime(roughly: ~N[2020-01-01 00:00:00], offset_required: false)
+           ~> []
+  end
+
   test "produces a useful mismatch for exactly mismatches" do
     assert "2020-01-01T00:00:00.000000Z"
            ~>> iso8601_datetime(exactly: ~U[3000-01-01 00:00:00.000000Z])