From c77bd48f953d9e501d44cd316aa3209490bce392 Mon Sep 17 00:00:00 2001
From: Moises Macia <mmacia@gmail.com>
Date: Fri, 24 Apr 2026 21:09:51 +0000
Subject: [PATCH] add tests

---
 test/feed_reader/streaming_test.exs | 160 ++++++++++++++++++++++++++++
 test/support/parser_halt_format.ex  |  24 +++++
 test/support/parser_halt_handler.ex |   6 ++
 3 files changed, 190 insertions(+)
 create mode 100644 test/feed_reader/streaming_test.exs
 create mode 100644 test/support/parser_halt_format.ex
 create mode 100644 test/support/parser_halt_handler.ex

diff --git a/test/feed_reader/streaming_test.exs b/test/feed_reader/streaming_test.exs
new file mode 100644
index 0000000..a446ef6
--- /dev/null
+++ b/test/feed_reader/streaming_test.exs
@@ -0,0 +1,160 @@
+defmodule FeedReader.StreamingTest do
+  use ExUnit.Case, async: true
+
+  alias FeedReader.{Feed, Item, Session}
+
+  @xml ~s(<rss version="2.0"><channel><title>Example</title><link>https://example.com/</link><item><title>First</title><guid>one</guid></item><item><title>Second</title><guid>two</guid></item></channel></rss>)
+  @atom_xml ~s(<feed xmlns="http://www.w3.org/2005/Atom"><title>Atom</title></feed>)
+  @rdf_xml ~s(<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"><channel><title>RDF</title></channel></rdf:RDF>)
+
+  test "emits feed metadata before items in one local pass" do
+    path = write_temp(@xml)
+
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %Session{fetch: nil, events: events}} = FeedReader.stream_file(path)
+
+    assert [
+             {:feed, %Feed{title: "Example"}},
+             {:item, %Item{uuid: "one"}},
+             {:item, %Item{uuid: "two"}}
+           ] = Enum.to_list(events)
+
+    assert File.read!(path) == @xml
+  end
+
+  test "delivers a malformed tail as a terminal error after earlier events" do
+    xml = @xml <> "<broken"
+    path = write_temp(xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %{events: events}} = FeedReader.stream_file(path)
+    events = Enum.to_list(events)
+
+    assert {:feed, %Feed{}} = Enum.at(events, 0)
+    assert {:item, %Item{uuid: "one"}} = Enum.at(events, 1)
+    assert {:item, %Item{uuid: "two"}} = Enum.at(events, 2)
+    assert {:error, _reason} = Enum.at(events, 3)
+    assert length(events) == 4
+    assert File.read!(path) == xml
+  end
+
+  test "rejects an unknown local format before creating a session" do
+    path = write_temp("<not-a-feed/>")
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:error, :unknown} = FeedReader.stream_file(path)
+    assert File.read!(path) == "<not-a-feed/>"
+  end
+
+  test "validates local paths and accepts an explicitly selected format module" do
+    assert {:error, :invalid_path} = FeedReader.stream_file(123)
+    assert {:error, :enoent} = FeedReader.stream_file("/path/that/does/not/exist")
+
+    assert {:error, :not_a_file} = FeedReader.stream_file(System.tmp_dir!())
+
+    path = write_temp(@xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %{events: events}} =
+             FeedReader.stream_file(path, format: FeedReader.Formats.RSS)
+
+    assert {:feed, %Feed{type: :rss}} = Enum.at(Enum.to_list(events), 0)
+  end
+
+  test "accepts explicit built-in Atom and RDF format IDs" do
+    atom_path = write_temp(@atom_xml)
+    rdf_path = write_temp(@rdf_xml)
+
+    on_exit(fn ->
+      File.rm(atom_path)
+      File.rm(rdf_path)
+    end)
+
+    assert {:ok, %{events: atom_events}} = FeedReader.stream_file(atom_path, format: :atom)
+    assert [{:feed, %Feed{title: "Atom", type: :atom}}] = Enum.to_list(atom_events)
+
+    assert {:ok, %{events: rdf_events}} = FeedReader.stream_file(rdf_path, format: :rdf)
+    assert [{:feed, %Feed{title: "RDF", type: :rdf}}] = Enum.to_list(rdf_events)
+  end
+
+  test "resolves a custom format by its ID" do
+    path = write_temp("<external-feed/>")
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %{events: events}} =
+             FeedReader.stream_file(path,
+               format: :external_test,
+               formats: [FeedReader.TestSupport.ExternalFormat]
+             )
+
+    assert [] = Enum.to_list(events)
+  end
+
+  test "uses an explicit format even when detection is disabled" do
+    path = write_temp(@xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %{events: events}} =
+             FeedReader.stream_file(path, format: :rss, max_detection_bytes: 0)
+
+    assert {:feed, %Feed{type: :rss}} = Enum.at(Enum.to_list(events), 0)
+  end
+
+  test "closes the parser when the consumer stops early" do
+    path = write_temp(@xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %{events: events}} = FeedReader.stream_file(path)
+    assert [{:feed, %Feed{}}] = events |> Stream.take(1) |> Enum.to_list()
+    assert File.read!(path) == @xml
+  end
+
+  test "returns a stable error for a non-atom format option" do
+    path = write_temp(@xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:error, :unknown} = FeedReader.stream_file(path, format: "rss")
+  end
+
+  test "treats an invalid detection limit as an unknown format" do
+    path = write_temp(@xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:error, :unknown} = FeedReader.stream_file(path, max_detection_bytes: 0)
+  end
+
+  test "delivers a parser halt as a terminal error event" do
+    path = write_temp(@xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %{events: events}} =
+             FeedReader.stream_file(
+               path,
+               format: :parser_halt,
+               formats: [FeedReader.TestSupport.ParserHaltFormat]
+             )
+
+    assert [{:error, :parser_halted}] = Enum.to_list(events)
+  end
+
+  test "stops cleanly when the parser process exits normally" do
+    path = write_temp(@xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %{events: events}} =
+             FeedReader.stream_file(path,
+               format: :parser_halt,
+               formats: [FeedReader.TestSupport.ParserHaltFormat],
+               normal_exit: true
+             )
+
+    assert [] = Enum.to_list(events)
+  end
+
+  defp write_temp(content) do
+    path = Path.join(System.tmp_dir!(), "feed_reader-#{System.unique_integer([:positive])}.xml")
+    File.write!(path, content)
+    path
+  end
+end
diff --git a/test/support/parser_halt_format.ex b/test/support/parser_halt_format.ex
new file mode 100644
index 0000000..1058bfc
--- /dev/null
+++ b/test/support/parser_halt_format.ex
@@ -0,0 +1,24 @@
+defmodule FeedReader.TestSupport.ParserHaltFormat do
+  @behaviour FeedReader.Format
+
+  @impl true
+  def id, do: :parser_halt
+
+  @impl true
+  def matches_prefix?(_prefix), do: true
+
+  @impl true
+  def handler, do: FeedReader.TestSupport.ParserHaltHandler
+
+  @impl true
+  def new_parser_state(_event_sink, opts) do
+    if Keyword.get(opts, :normal_exit), do: exit(:normal)
+    nil
+  end
+
+  @impl true
+  def normalize_feed(_state, _opts), do: %FeedReader.Feed{}
+
+  @impl true
+  def normalize_item(_raw_item, _feed, _opts), do: :skip
+end
diff --git a/test/support/parser_halt_handler.ex b/test/support/parser_halt_handler.ex
new file mode 100644
index 0000000..12ad564
--- /dev/null
+++ b/test/support/parser_halt_handler.ex
@@ -0,0 +1,6 @@
+defmodule FeedReader.TestSupport.ParserHaltHandler do
+  @behaviour Saxy.Handler
+
+  @impl true
+  def handle_event(_event, _data, _state), do: {:halt, :stopped}
+end