From 2424a989bc0197dfbebd4999ecb9dbf8e65cc2da Mon Sep 17 00:00:00 2001
From: Moises Macia <mmacia@gmail.com>
Date: Mon, 18 May 2026 21:29:10 +0000
Subject: [PATCH] add tests

---
 test/feed_reader/collector_test.exs     | 130 ++++++++++++++++++++++++
 test/support/external_format_handler.ex |   1 +
 2 files changed, 131 insertions(+)
 create mode 100644 test/feed_reader/collector_test.exs

diff --git a/test/feed_reader/collector_test.exs b/test/feed_reader/collector_test.exs
new file mode 100644
index 0000000..bcdc03f
--- /dev/null
+++ b/test/feed_reader/collector_test.exs
@@ -0,0 +1,130 @@
+defmodule FeedReader.CollectorTest do
+  use ExUnit.Case, async: true
+
+  alias FeedReader.{Feed, Item, ParseResult}
+
+  @xml ~s(<rss version="2.0"><channel><title>Example</title><item><title>First</title><guid>one</guid></item><item><title>Second</title><guid>two</guid></item></channel></rss>)
+
+  test "collects binary XML through the local event stream" do
+    assert {:ok, %ParseResult{feed: %Feed{title: "Example"}, items: items}} =
+             FeedReader.parse_binary(@xml, max_items: 2)
+
+    assert [%Item{uuid: "one"}, %Item{uuid: "two"}] = items
+  end
+
+  test "collects chunk enumerables without requiring a path" do
+    chunks = String.graphemes(@xml)
+
+    assert {:ok, %ParseResult{items: [%Item{uuid: "one"}, %Item{uuid: "two"}]}} =
+             FeedReader.parse_stream(chunks, max_items: 2)
+  end
+
+  test "collects caller-owned files and preserves them" do
+    path = write_temp(@xml)
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:ok, %ParseResult{items: items}} = FeedReader.parse_file(path, max_items: 2)
+    assert length(items) == 2
+    assert File.read!(path) == @xml
+  end
+
+  test "requires a positive max_items for every collector" do
+    assert {:error, {:invalid_option, :max_items}} = FeedReader.parse_binary(@xml)
+    assert {:error, {:invalid_option, :max_items}} = FeedReader.parse_file("missing.xml")
+    assert {:error, {:invalid_option, :max_items}} = FeedReader.parse_stream([])
+    assert {:error, {:invalid_option, :max_items}} = FeedReader.parse_binary(@xml, max_items: 0)
+    assert {:error, {:invalid_option, :max_items}} = FeedReader.parse_stream([], max_items: :all)
+  end
+
+  test "propagates local source errors" do
+    assert {:error, :enoent} = FeedReader.parse_file("/path/that/does/not/exist", max_items: 1)
+  end
+
+  test "filters before counting and collecting" do
+    filter = fn %Item{uuid: uuid} -> uuid == "two" end
+
+    assert {:ok, %ParseResult{items: [%Item{uuid: "two"}]}} =
+             FeedReader.parse_binary(@xml, max_items: 1, item_filter: filter)
+  end
+
+  test "reports an item beyond the bound instead of returning a partial result" do
+    assert {:error, {:max_items_exceeded, 1}} = FeedReader.parse_binary(@xml, max_items: 1)
+  end
+
+  test "continues to the terminal parser event before returning a malformed-tail error" do
+    assert {:error, _reason} = FeedReader.parse_binary(@xml <> "<broken", max_items: 2)
+  end
+
+  test "rejects invalid chunks and binary arguments" do
+    assert {:error, :invalid_chunk} =
+             FeedReader.parse_stream([@xml, 123], max_items: 2)
+
+    assert {:error, :invalid_binary} = FeedReader.parse_binary(123, max_items: 2)
+  end
+
+  test "returns an error for an invalid item filter" do
+    path = write_temp("<external-feed/>")
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:error, {:invalid_option, :item_filter}} =
+             FeedReader.parse_file(path,
+               format: :external_test,
+               formats: [FeedReader.TestSupport.ExternalFormat],
+               max_items: 1,
+               item_filter: :not_a_function
+             )
+  end
+
+  test "rejects collection without feed metadata" do
+    path = write_temp("<external-feed/>")
+    on_exit(fn -> File.rm(path) end)
+
+    assert {:error, :feed_metadata_missing} =
+             FeedReader.parse_file(path,
+               format: :external_test,
+               formats: [FeedReader.TestSupport.ExternalFormat],
+               max_items: 1
+             )
+  end
+
+  test "handles duplicate metadata, ignored events, and parser errors" do
+    feed = %Feed{title: "Custom", type: :rss}
+    item = %Item{uuid: "custom"}
+    path = write_temp("<external-feed/>")
+    on_exit(fn -> File.rm(path) end)
+
+    opts = [
+      format: :external_test,
+      formats: [FeedReader.TestSupport.ExternalFormat],
+      max_items: 1,
+      collector_events: [{:feed, feed}, :ignored, {:item, item}, {:feed, feed}]
+    ]
+
+    assert {:ok, %ParseResult{feed: ^feed, items: [^item]}} = FeedReader.parse_file(path, opts)
+
+    assert {:error, :custom_parser_error} =
+             FeedReader.parse_file(
+               path,
+               Keyword.put(opts, :collector_events, [{:error, :custom_parser_error}])
+             )
+  end
+
+  test "reports an enumerable failure and still cleans its temporary source" do
+    chunks =
+      Stream.resource(fn -> :ok end, fn _state -> raise "chunk failure" end, fn _ -> :ok end)
+
+    assert {:error, {:stream_write_failed, %RuntimeError{message: "chunk failure"}}} =
+             FeedReader.parse_stream(chunks, max_items: 1)
+  end
+
+  defp write_temp(content) do
+    path =
+      Path.join(
+        System.tmp_dir!(),
+        "feed_reader-collector-#{System.unique_integer([:positive])}.xml"
+      )
+
+    File.write!(path, content)
+    path
+  end
+end
diff --git a/test/support/external_format_handler.ex b/test/support/external_format_handler.ex
index 22b8591..f3fd89d 100644
--- a/test/support/external_format_handler.ex
+++ b/test/support/external_format_handler.ex
@@ -7,6 +7,7 @@ defmodule FeedReader.TestSupport.ExternalFormatHandler do
   @impl true
   def handle_event(:start_document, _data, %{opts: opts} = state) do
     if Keyword.get(opts, :emit_event), do: emit_event(state)
+    Enum.each(Keyword.get(opts, :collector_events, []), fn event -> state.event_sink.(event) end)
 
     {:ok, state}
   end