Initial yt-dlp implementation (#3)

* Added basic runner for yt-dlp commands

* Updated formatting rules

* Added JSON runner; Added test script for CLI interactions

* Reworked yt-dlp runner; added proper test mocks

test/pinchflat/downloader_backends/yt_dlp/command_runner_test.exs

@@ -0,0 +1,72 @@
+defmodule Pinchflat.DownloaderBackends.YtDlp.CommandRunnerTest do
+  use ExUnit.Case, async: true
+
+  alias Pinchflat.DownloaderBackends.YtDlp.CommandRunner, as: Runner
+
+  @original_executable Application.compile_env(:pinchflat, :yt_dlp_executable)
+  @video_url "https://www.youtube.com/watch?v=9bZkp7q19f0"
+
+  setup do
+    on_exit(&reset_executable/0)
+  end
+
+  describe "run/2" do
+    test "it returns the output and status when the command succeeds" do
+      assert {:ok, _output} = Runner.run(@video_url, [])
+    end
+
+    test "it converts symbol k-v arg keys to kebab case" do
+      assert {:ok, output} = Runner.run(@video_url, buffer_size: 1024)
+
+      assert String.contains?(output, "--buffer-size 1024")
+    end
+
+    test "it keeps string k-v arg keys untouched" do
+      assert {:ok, output} = Runner.run(@video_url, [{"--under_score", 1024}])
+
+      assert String.contains?(output, "--under_score 1024")
+    end
+
+    test "it converts symbol arg keys to kebab case" do
+      assert {:ok, output} = Runner.run(@video_url, [:ignore_errors])
+
+      assert String.contains?(output, "--ignore-errors")
+    end
+
+    test "it keeps string arg keys untouched" do
+      assert {:ok, output} = Runner.run(@video_url, ["-v"])
+
+      assert String.contains?(output, "-v")
+      refute String.contains?(output, "--v")
+    end
+
+    test "it places arg keys (flags) at the beginning of the command" do
+      assert {:ok, output} =
+               Runner.run(@video_url, [{"--under_score", 1024}, :ignore_errors])
+
+      assert String.contains?(output, "--ignore-errors --under_score 1024")
+    end
+
+    test "it includes the video url as the last argument" do
+      assert {:ok, output} = Runner.run(@video_url, [:ignore_errors])
+
+      assert String.contains?(output, "--ignore-errors #{@video_url}\n")
+    end
+
+    test "it returns the output and status when the command fails" do
+      wrap_executable("/bin/false", fn ->
+        assert {:error, "", 1} = Runner.run(@video_url, [])
+      end)
+    end
+  end
+
+  defp wrap_executable(new_executable, fun) do
+    Application.put_env(:pinchflat, :yt_dlp_executable, new_executable)
+    fun.()
+    reset_executable()
+  end
+
+  def reset_executable do
+    Application.put_env(:pinchflat, :yt_dlp_executable, @original_executable)
+  end
+end

test/pinchflat/downloader_backends/yt_dlp/video_collection_test.exs

@@ -0,0 +1,44 @@
+defmodule Pinchflat.DownloaderBackends.YtDlp.VideoCollectionTest do
+  use ExUnit.Case, async: true
+  import Mox
+
+  alias Pinchflat.DownloaderBackends.YtDlp.VideoCollection, as: VideoCollection
+
+  @channel_url "https://www.youtube.com/@TheUselessTrials"
+
+  setup :verify_on_exit!
+
+  describe "get_video_ids/2" do
+    test "returns a list of video ids with no blank elements" do
+      expect(CommandRunnerMock, :run, fn _url, _opts -> {:ok, "id1\nid2\n\nid3\n"} end)
+
+      assert {:ok, ["id1", "id2", "id3"]} = VideoCollection.get_video_ids(@channel_url)
+    end
+
+    test "it passes the expected default args" do
+      expect(CommandRunnerMock, :run, fn _url, opts ->
+        assert opts == [:simulate, :skip_download, :get_id]
+
+        {:ok, ""}
+      end)
+
+      assert {:ok, _} = VideoCollection.get_video_ids(@channel_url)
+    end
+
+    test "it passes the expected custom args" do
+      expect(CommandRunnerMock, :run, fn _url, opts ->
+        assert opts == [:custom_arg, :simulate, :skip_download, :get_id]
+
+        {:ok, ""}
+      end)
+
+      assert {:ok, _} = VideoCollection.get_video_ids(@channel_url, [:custom_arg])
+    end
+
+    test "returns the error straight through when the command fails" do
+      expect(CommandRunnerMock, :run, fn _url, _opts -> {:error, "Big issue", 1} end)
+
+      assert {:error, "Big issue", 1} = VideoCollection.get_video_ids(@channel_url)
+    end
+  end
+end

test/pinchflat/utils/string_utils_test.exs

@@ -0,0 +1,15 @@
+defmodule Pinchflat.Utils.StringUtilsTest do
+  use ExUnit.Case, async: true
+
+  alias Pinchflat.Utils.StringUtils, as: StringUtils
+
+  describe "to_kebab_case/1" do
+    test "converts a space-delimited string to kebab-case" do
+      assert StringUtils.to_kebab_case("hello world") == "hello-world"
+    end
+
+    test "converts an underscore-delimited string to kebab-case" do
+      assert StringUtils.to_kebab_case("hello_world") == "hello-world"
+    end
+  end
+end

test/support/scripts/yt-dlp-mocks/repeater.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+if [[ "$@" == *"--dump-json"* ]]; then
+  echo '{ "args": "'$@'"}'
+else
+  echo $@
+fi

test/test_helper.exs

@@ -1,2 +1,5 @@
+Mox.defmock(CommandRunnerMock, for: Pinchflat.DownloaderBackends.BackendCommandRunner)
+Application.put_env(:pinchflat, :yt_dlp_runner, CommandRunnerMock)
+
 ExUnit.start()
 Ecto.Adapters.SQL.Sandbox.mode(Pinchflat.Repo, :manual)