Update Directions In TUTORIAL.md; Add Unit Tests To non_user_endpoints test.py (#1136)

* Update navigational directions in Step 1(A)

* Combine directions in Step 1(B) and Step 2(C) and remove Step 2(C)

* Update navigational directions and verbage in Step 1(C)

* Change reference from Step 1(C) to Step 1(B) in Step 2(D)

* Update capitalization in Prerequisites Step 3

* Add directions for installing Spotipy in Prerequisites Step 1(A)

* List updates to TUTORIAL.md file in CHANGELOG.md

* Update docstrings for funcs in lines 340-585

* Add unit tests for artist ID and URL

* Add test_artists_mixed_ids

* Updated CHANGELOG.md and TUTORIAL.md as requested

* Update client.py and test.py

* Fix linting issue

* Remove duplicate line; Change order of prerequisites

* Update local repo

* Add test_artists_mixed_ids

* Add Radiohead ID and URL; Add qotsa URL

* Add test_artist_url

* Comment out three failing tests

* Fix linting errors

* Uncommenting out failed tests

* Add test_artist_id

* List changes in CHANGELOG.md

* Add line breaks at the end of files.

* Remove multiple spaces

Also I've removed a sentence that just doesn't make sense in my eyes, but was added before this PR.

---------

Co-authored-by: Niko <github@dieserniko.link>

tests/integration/non_user_endpoints/test.py

@@ -37,12 +37,19 @@ class AuthTestSpotipy(unittest.TestCase):
     creep_urn = 'spotify:track:6b2oQwSGFkzsMtQruIWm2p'
     creep_id = '6b2oQwSGFkzsMtQruIWm2p'
     creep_url = 'http://open.spotify.com/track/6b2oQwSGFkzsMtQruIWm2p'
+
     el_scorcho_urn = 'spotify:track:0Svkvt5I79wficMFgaqEQJ'
     el_scorcho_bad_urn = 'spotify:track:0Svkvt5I79wficMFgaqEQK'
     pinkerton_urn = 'spotify:album:04xe676vyiTeYNXw15o9jT'
     weezer_urn = 'spotify:artist:3jOstUTkEu2JkjvRdBA5Gu'
+
     pablo_honey_urn = 'spotify:album:6AZv3m27uyRxi8KyJSfUxL'
     radiohead_urn = 'spotify:artist:4Z8W4fKeB5YxbusRsdQVPb'
+    radiohead_id = "4Z8W4fKeB5YxbusRsdQVPb"
+    radiohead_url = "https://open.spotify.com/artist/4Z8W4fKeB5YxbusRsdQVPb"
+
+    qotsa_url = "https://open.spotify.com/artist/4pejUc4iciQfgdX6OKulQn"
+
     angeles_haydn_urn = 'spotify:album:1vAbqAeuJVWNAe7UR00bdM'
     heavyweight_urn = 'spotify:show:5c26B28vZMN8PG0Nppmn5G'
     heavyweight_id = '5c26B28vZMN8PG0Nppmn5G'
@@ -101,11 +108,24 @@ class AuthTestSpotipy(unittest.TestCase):
         artist = self.spotify.artist(self.radiohead_urn)
         self.assertTrue(artist['name'] == 'Radiohead')
 
+    def test_artist_url(self):
+        artist = self.spotify.artist(self.radiohead_url)
+        self.assertTrue(artist['name'] == 'Radiohead')
+
+    def test_artist_id(self):
+        artist = self.spotify.artist(self.radiohead_id)
+        self.assertTrue(artist['name'] == 'Radiohead')
+
     def test_artists(self):
         results = self.spotify.artists([self.weezer_urn, self.radiohead_urn])
         self.assertTrue('artists' in results)
         self.assertTrue(len(results['artists']) == 2)
 
+    def test_artists_mixed_ids(self):
+        results = self.spotify.artists([self.weezer_urn, self.radiohead_id, self.qotsa_url])
+        self.assertTrue('artists' in results)
+        self.assertTrue(len(results['artists']) == 3)
+
     def test_album_urn(self):
         album = self.spotify.album(self.pinkerton_urn)
         self.assertTrue(album['name'] == 'Pinkerton')