[WIP] Monkeypatch tests (#448)

* Parameterize test_internals.py

* Create test_spotify_tools.py

* Monkeypatch pafy.download

* Monkeypatch YouTube search page

* Replace globals with fixtures

* Add missing urllib import, re-ordering and rename test_with_metadata.py

* Avoid creating temp directory in current working directory during test

* Update CHANGES.md

test/test_youtube_tools.py

@@ -0,0 +1,149 @@
+import os
+import builtins
+
+from spotdl import const
+from spotdl import internals
+from spotdl import spotify_tools
+from spotdl import youtube_tools
+from spotdl import downloader
+
+import loader
+import pytest
+
+loader.load_defaults()
+
+YT_API_KEY = "AIzaSyAnItl3udec-Q1d5bkjKJGL-RgrKO_vU90"
+
+TRACK_SEARCH = "Tony's Videos VERY SHORT VIDEO 28.10.2016"
+EXPECTED_TITLE = TRACK_SEARCH
+EXPECTED_YT_URL = "http://youtube.com/watch?v=qOOcy2-tmbk"
+EXPECTED_YT_URLS = (EXPECTED_YT_URL, "http://youtube.com/watch?v=5USR1Omo7f0")
+
+RESULT_COUNT_SEARCH = "she is still sleeping SAO"
+
+EXPECTED_YT_API_KEY = "AIzaSyC6cEeKlxtOPybk9sEe5ksFN5sB-7wzYp0"
+EXPECTED_YT_API_KEY_CUSTOM = "some_api_key"
+
+
+class TestYouTubeAPIKeys:
+    def test_custom(self):
+        const.args.youtube_api_key = EXPECTED_YT_API_KEY_CUSTOM
+        youtube_tools.set_api_key()
+        key = youtube_tools.pafy.g.api_key
+        assert key == EXPECTED_YT_API_KEY_CUSTOM
+
+    def test_default(self):
+        const.args.youtube_api_key = None
+        youtube_tools.set_api_key()
+        key = youtube_tools.pafy.g.api_key
+        assert key == EXPECTED_YT_API_KEY
+
+
+@pytest.fixture(scope="module")
+def metadata_fixture():
+    metadata = spotify_tools.generate_metadata(TRACK_SEARCH)
+    return metadata
+
+
+def test_metadata(metadata_fixture):
+    expect_metadata = None
+    assert metadata_fixture == expect_metadata
+
+
+class TestArgsManualResultCount:
+    # Regresson test for issue #264
+    def test_scrape(self):
+        const.args.manual = True
+        url = youtube_tools.GenerateYouTubeURL(RESULT_COUNT_SEARCH, meta_tags=None)
+        video_ids = url.scrape(bestmatch=False)
+        # Web scraping gives us all videos on the 1st page
+        assert len(video_ids) == 20
+
+    def test_api(self):
+        url = youtube_tools.GenerateYouTubeURL(RESULT_COUNT_SEARCH, meta_tags=None)
+        video_ids = url.api(bestmatch=False)
+        const.args.manual = False
+        # API gives us 50 videos (or as requested)
+        assert len(video_ids) == 50
+
+
+class TestYouTubeURL:
+    def test_only_music_category(self, metadata_fixture):
+        const.args.music_videos_only = True
+        url = youtube_tools.generate_youtube_url(TRACK_SEARCH, metadata_fixture)
+        # YouTube keeps changing its results
+        assert url in EXPECTED_YT_URLS
+
+    def test_all_categories(self, metadata_fixture):
+        const.args.music_videos_only = False
+        url = youtube_tools.generate_youtube_url(TRACK_SEARCH, metadata_fixture)
+        assert url == EXPECTED_YT_URL
+
+    def test_args_manual(self, metadata_fixture, monkeypatch):
+        const.args.manual = True
+        monkeypatch.setattr("builtins.input", lambda x: "1")
+        url = youtube_tools.generate_youtube_url(TRACK_SEARCH, metadata_fixture)
+        assert url == EXPECTED_YT_URL
+
+    def test_args_manual_none(self, metadata_fixture, monkeypatch):
+        expect_url = None
+        monkeypatch.setattr("builtins.input", lambda x: "0")
+        url = youtube_tools.generate_youtube_url(TRACK_SEARCH, metadata_fixture)
+        const.args.manual = False
+        assert url == expect_url
+
+
+@pytest.fixture(scope="module")
+def content_fixture(metadata_fixture):
+    content = youtube_tools.go_pafy(TRACK_SEARCH, metadata_fixture)
+    return content
+
+
+@pytest.fixture(scope="module")
+def title_fixture(content_fixture):
+    title = youtube_tools.get_youtube_title(content_fixture)
+    return title
+
+
+class TestYouTubeTitle:
+    def test_single_download_with_youtube_api(self, title_fixture):
+        const.args.youtube_api_key = YT_API_KEY
+        youtube_tools.set_api_key()
+        assert title_fixture == EXPECTED_TITLE
+
+    def test_download_from_list_without_youtube_api(self, metadata_fixture, content_fixture):
+        const.args.youtube_api_key = None
+        youtube_tools.set_api_key()
+        content_fixture = youtube_tools.go_pafy(TRACK_SEARCH, metadata_fixture)
+        title = youtube_tools.get_youtube_title(content_fixture, 1)
+        assert title == "1. {0}".format(EXPECTED_TITLE)
+
+
+@pytest.fixture(scope="module")
+def filename_fixture(title_fixture):
+    filename = internals.sanitize_title(title_fixture)
+    return filename
+
+
+def test_check_exists(metadata_fixture, filename_fixture, tmpdir):
+    expect_check = False
+    const.args.folder = str(tmpdir)
+    # prerequisites for determining filename
+    track_existence = downloader.CheckExists(filename_fixture, metadata_fixture)
+    check = track_existence.already_exists(TRACK_SEARCH)
+    assert check == expect_check
+
+
+class TestDownload:
+    def test_webm(self, content_fixture, filename_fixture, monkeypatch):
+        # content_fixture does not have any .webm audiostream
+        expect_download = False
+        monkeypatch.setattr("pafy.backend_shared.BaseStream.download", lambda x: None)
+        download = youtube_tools.download_song(filename_fixture + ".webm", content_fixture)
+        assert download == expect_download
+
+    def test_other(self, content_fixture, filename_fixture, monkeypatch):
+        expect_download = False
+        monkeypatch.setattr("pafy.backend_shared.BaseStream.download", lambda x: None)
+        download = youtube_tools.download_song(filename_fixture + ".fake_extension", content_fixture)
+        assert download == expect_download