Simplify prefix a bit

tests/prefix_test.py

@@ -1,6 +1,6 @@
 from __future__ import unicode_literals
 
-import os
+import os.path
 
 import pytest
 
@@ -12,30 +12,16 @@ def norm_slash(*args):
 
 
 @pytest.mark.parametrize(
-    ('input', 'expected_prefix'), (
-        norm_slash('.', './'),
-        norm_slash('foo', 'foo/'),
-        norm_slash('bar/', 'bar/'),
-        norm_slash('foo/bar', 'foo/bar/'),
-        norm_slash('foo/bar/', 'foo/bar/'),
+    ('prefix', 'path_end', 'expected_output'),
+    (
+        norm_slash('foo', '', 'foo'),
+        norm_slash('foo', 'bar', 'foo/bar'),
+        norm_slash('foo/bar', '../baz', 'foo/baz'),
+        norm_slash('./', 'bar', 'bar'),
+        norm_slash('./', '', '.'),
+        norm_slash('/tmp/foo', '/tmp/bar', '/tmp/bar'),
     ),
 )
-def test_init_normalizes_path_endings(input, expected_prefix):
-    instance = Prefix(input)
-    assert instance.prefix_dir == expected_prefix
-
-
-PATH_TESTS = (
-    norm_slash('foo', '', 'foo'),
-    norm_slash('foo', 'bar', 'foo/bar'),
-    norm_slash('foo/bar', '../baz', 'foo/baz'),
-    norm_slash('./', 'bar', 'bar'),
-    norm_slash('./', '', '.'),
-    norm_slash('/tmp/foo', '/tmp/bar', '/tmp/bar'),
-)
-
-
-@pytest.mark.parametrize(('prefix', 'path_end', 'expected_output'), PATH_TESTS)
 def test_path(prefix, path_end, expected_output):
     instance = Prefix(prefix)
     ret = instance.path(path_end)
@@ -48,10 +34,7 @@ def test_path_multiple_args():
     assert ret == os.path.join('foo', 'bar', 'baz')
 
 
-def test_exists_does_not_exist(tmpdir):
+def test_exists(tmpdir):
     assert not Prefix(str(tmpdir)).exists('foo')
-
-
-def test_exists_does_exist(tmpdir):
     tmpdir.ensure('foo')
     assert Prefix(str(tmpdir)).exists('foo')