add tests

test/feed_reader/remote_session_test.exs

@@ -0,0 +1,107 @@
+defmodule FeedReader.RemoteSessionTest do
+  use ExUnit.Case, async: false
+
+  alias FeedReader.{Feed, Item, RemoteResult, Session}
+
+  @xml ~s(<rss version="2.0"><channel><title>Remote</title><item><title>First</title><guid>one</guid></item><item><title>Second</title><guid>two</guid></item></channel></rss>)
+
+  test "streams remote events with fetch metadata and removes the file after completion" do
+    assert {:ok, %Session{fetch: fetch, events: events, resource: %{path: path}}} =
+             stream(@xml)
+
+    assert fetch.final_url == "https://example.com/final.xml"
+    assert fetch.etag == "\"v1\""
+    assert File.exists?(path)
+
+    assert [
+             {:feed, %Feed{title: "Remote", feed_url: "https://example.com/final.xml"}},
+             {:item, %Item{uuid: "one"}},
+             {:item, %Item{uuid: "two"}}
+           ] = Enum.to_list(events)
+
+    refute File.exists?(path)
+  end
+
+  test "closes an unstarted or partially consumed session idempotently" do
+    assert {:ok, %Session{resource: %{path: path}} = session} = stream(@xml)
+    assert :ok = FeedReader.close(session)
+    assert :ok = FeedReader.close(session)
+    refute File.exists?(path)
+
+    assert {:ok, %Session{events: events2, resource: %{path: path2}}} = stream(@xml)
+    assert [{:feed, %Feed{}}] = events2 |> Stream.take(1) |> Enum.to_list()
+    refute File.exists?(path2)
+  end
+
+  test "collects remote feeds within the required finite item limit" do
+    assert {:error, {:invalid_option, :max_items}} = fetch_and_parse(@xml, [])
+    refute_received {:transport_request, _url}
+
+    assert {:ok, %RemoteResult{feed: %Feed{title: "Remote"}, items: items, fetch: fetch}} =
+             fetch_and_parse(@xml, max_items: 2)
+
+    assert [%Item{uuid: "one"}, %Item{uuid: "two"}] = items
+    assert fetch.status == 200
+
+    before = download_files()
+    assert {:error, {:max_items_exceeded, 1}} = fetch_and_parse(@xml, max_items: 1)
+    assert download_files() == before
+
+    assert {:error, _reason} = fetch_and_parse(@xml <> "<broken", max_items: 2)
+    assert download_files() == before
+  end
+
+  test "returns unchanged outcomes without parsing and cleans invalid-format downloads" do
+    assert {:ok, :not_modified} =
+             fetch_and_parse("", max_items: 1, response: response([], [], 304))
+
+    assert {:ok, :not_changed} =
+             fetch_and_parse(@xml, max_items: 1, previous_checksum: checksum(@xml))
+
+    before = download_files()
+    assert {:error, :unknown} = stream("<unknown/>", format: :invalid_format)
+    assert download_files() == before
+  end
+
+  test "covers default options and closing a local session" do
+    assert {:error, :invalid_url} = FeedReader.stream(:invalid)
+
+    assert {:error, {:invalid_option, :max_items}} =
+             FeedReader.fetch_and_parse("https://example.com/feed.xml")
+
+    assert :ok = FeedReader.close(%Session{})
+  end
+
+  defp stream(xml, opts \\ []) do
+    FeedReader.stream("https://example.com/feed.xml", request_opts(xml, opts))
+  end
+
+  defp fetch_and_parse(xml, opts) do
+    request = request_opts(xml, opts)
+    FeedReader.fetch_and_parse("https://example.com/feed.xml", request)
+  end
+
+  defp request_opts(xml, opts) do
+    response = Keyword.get(opts, :response, response([xml], [{"ETag", "\"v1\""}]))
+
+    [
+      http_client: FeedReader.TestSupport.TransportClient,
+      response: response,
+      test_pid: self()
+    ] ++ Keyword.delete(opts, :response)
+  end
+
+  defp response(body, headers, status \\ 200),
+    do: %{
+      status: status,
+      headers: headers,
+      final_url: "https://example.com/final.xml",
+      body: body
+    }
+
+  defp checksum(xml), do: Base.encode16(:crypto.hash(:md5, xml), case: :lower)
+
+  defp download_files do
+    Path.join(System.tmp_dir!(), "feed_reader-download-*.xml") |> Path.wildcard()
+  end
+end