simplify test structure to be more inline with pytest recommendations (#140)

Signed-off-by: Matthew Peveler <matt.peveler@gmail.com>

Author: MasterOdin

tests/test_tldr.py

@@ -1,34 +1,33 @@
 import sys
 import io
 import types
-import unittest
-import unittest.mock
+from unittest import mock
 import tldr
 import pytest
 
 
-class TLDRTests(unittest.TestCase):
-    def test_whole_page(self):
-        with open("tests/data/gem.md", "rb") as f_original:
-            with open("tests/data/gem_rendered", "rb") as f_rendered:
-                old_stdout = sys.stdout
-                sys.stdout = io.StringIO()
-                sys.stdout.buffer = types.SimpleNamespace()
-                sys.stdout.buffer.write = lambda x: sys.stdout.write(x.decode("utf-8"))
-                tldr.output(f_original)
+def test_whole_page():
+    with open("tests/data/gem.md", "rb") as f_original:
+        with open("tests/data/gem_rendered", "rb") as f_rendered:
+            old_stdout = sys.stdout
+            sys.stdout = io.StringIO()
+            sys.stdout.buffer = types.SimpleNamespace()
+            sys.stdout.buffer.write = lambda x: sys.stdout.write(x.decode("utf-8"))
+            tldr.output(f_original)
 
-                sys.stdout.seek(0)
-                tldr_output = sys.stdout.read().encode("utf-8")
-                sys.stdout = old_stdout
+            sys.stdout.seek(0)
+            tldr_output = sys.stdout.read().encode("utf-8")
+            sys.stdout = old_stdout
 
-                correct_output = f_rendered.read()
-                self.assertEqual(tldr_output, correct_output)
+            correct_output = f_rendered.read()
+            assert tldr_output == correct_output
 
-    def test_error_message(self):
-        with unittest.mock.patch("sys.argv", ["tldr", "73eb6f19cd6f"]):
-            with pytest.raises(SystemExit) as pytest_wrapped_e:
-                tldr.main()
-            correct_output = "`73eb6f19cd6f` documentation is not available. Consider contributing Pull Request to https://github.com/tldr-pages/tldr"  # noqa
-            print("Test {}".format(pytest_wrapped_e))
-            assert pytest_wrapped_e.type == SystemExit
-            assert str(pytest_wrapped_e.value) == correct_output
+
+def test_error_message():
+    with mock.patch("sys.argv", ["tldr", "73eb6f19cd6f"]):
+        with pytest.raises(SystemExit) as pytest_wrapped_e:
+            tldr.main()
+        correct_output = "`73eb6f19cd6f` documentation is not available. Consider contributing Pull Request to https://github.com/tldr-pages/tldr"  # noqa
+        print("Test {}".format(pytest_wrapped_e))
+        assert pytest_wrapped_e.type == SystemExit
+        assert str(pytest_wrapped_e.value) == correct_output