Add a few initial test cases, could use more

youtube_transcript_api/test/test_formatters.py

@@ -0,0 +1,57 @@
+import json
+from mock import MagicMock
+from unittest import TestCase
+
+from youtube_transcript_api.formatters import (
+    Formatter,
+    JSONFormatter,
+    TextFormatter,
+    WebVTTFormatter
+)
+
+
+class TestFormatters(TestCase):
+    def setUp(self):
+        self.transcript = [
+            {'text': 'Test line 1', 'start': 0.0, 'duration': 1.50},
+            {'text': 'line between', 'start': 1.5, 'duration': 2.0},
+            {'text': 'testing the end line', 'start': 2.5, 'duration': 3.25}
+        ]
+    
+    def test_base_formatter_valid_type(self):
+        with self.assertRaises(TypeError) as err:
+            Formatter({"test": []})
+        expected_err = "'transcript' must be of type: List"
+        self.assertEqual(expected_err, str(err.exception))
+    
+    def test_base_formatter_format_call(self):
+        with self.assertRaises(NotImplementedError) as err:
+            Formatter(self.transcript).format()
+        
+        expected_err = "A subclass of Formatter must implement their own " \
+            ".format() method."
+        self.assertEqual(expected_err, str(err.exception))
+
+    def test_webvtt_formatter_starting(self):
+        content = WebVTTFormatter(self.transcript).format()
+        lines = content.split('\n')
+        # test starting lines
+        self.assertEqual(lines[0], "WEBVTT")
+        self.assertEqual(lines[1], "")
+    
+    def test_webvtt_formatter_ending(self):
+        content = WebVTTFormatter(self.transcript).format()
+        lines = content.split('\n')
+        # test ending lines
+        self.assertEqual(lines[-2], self.transcript[-1]['text'])
+        self.assertEqual(lines[-1], "")
+    
+    def test_json_formatter(self):
+        content = JSONFormatter(self.transcript).format()
+        self.assertEqual(json.loads(content), self.transcript)
+
+    def test_text_formatter(self):
+        content = TextFormatter(self.transcript).format()
+        lines = content.split('\n')
+        self.assertEqual(lines[0], self.transcript[0]["text"])
+        self.assertEqual(lines[-1], self.transcript[-1]["text"])