Use pathlib instead of os.path where applicable (#112)

* Use pathlib in test_creation.py

* Use pathlib for PROJECT_DIR example in make_dataset.py

* Add pathlib2 for backwards compatibility if project is Python 2

tests/test_creation.py

@@ -1,93 +1,86 @@
 import os
+import pytest
 import shutil
+from pathlib import Path
 
 from cookiecutter import main
-import pytest
 
-CCDS_ROOT = os.path.abspath(
-                os.path.join(
-                    __file__,
-                    os.pardir,
-                    os.pardir
-                )
-            )
+CCDS_ROOT = Path(__file__).parents[1].resolve()
 
 
 @pytest.fixture(scope='function')
 def default_baked_project(tmpdir):
-    out_dir = str(tmpdir.mkdir('data-project'))
+    temp = tmpdir.mkdir('data-project')
+    out_dir = Path(temp).resolve()
 
     main.cookiecutter(
-        CCDS_ROOT,
+        str(CCDS_ROOT),
         no_input=True,
         extra_context={},
         output_dir=out_dir
     )
 
     # default project name is project_name
-    yield os.path.join(out_dir, 'project_name')
+    yield out_dir / 'project_name'
 
     # cleanup after
     shutil.rmtree(out_dir)
 
 
 def test_readme(default_baked_project):
-    readme_path = os.path.join(default_baked_project, 'README.md')
+    readme_path = default_baked_project / 'README.md'
 
-    assert os.path.exists(readme_path)
+    assert readme_path.exists()
     assert no_curlies(readme_path)
 
 
 def test_license(default_baked_project):
-    license_path = os.path.join(default_baked_project, 'LICENSE')
+    license_path = default_baked_project / 'LICENSE'
 
-    assert os.path.exists(license_path)
+    assert license_path.exists()
     assert no_curlies(license_path)
 
 
 def test_requirements(default_baked_project):
-    reqs_path = os.path.join(default_baked_project, 'requirements.txt')
+    reqs_path = default_baked_project / 'requirements.txt'
 
-    assert os.path.exists(reqs_path)
+    assert reqs_path.exists()
     assert no_curlies(reqs_path)
 
 
 def test_makefile(default_baked_project):
-    makefile_path = os.path.join(default_baked_project, 'Makefile')
+    makefile_path = default_baked_project / 'Makefile'
 
-    assert os.path.exists(makefile_path)
+    assert makefile_path.exists()
     assert no_curlies(makefile_path)
 
 
 def test_folders(default_baked_project):
     expected_dirs = [
         'data',
-        os.path.join('data', 'external'),
-        os.path.join('data', 'interim'),
-        os.path.join('data', 'processed'),
-        os.path.join('data', 'raw'),
+        'data/external',
+        'data/interim',
+        'data/processed',
+        'data/raw',
         'docs',
         'models',
         'notebooks',
         'references',
         'reports',
-        os.path.join('reports', 'figures'),
+        'reports/figures',
         'src',
-        os.path.join('src', 'data'),
-        os.path.join('src', 'features'),
-        os.path.join('src', 'models'),
-        os.path.join('src', 'visualization')
+        'src/data',
+        'src/features',
+        'src/models',
+        'src/visualization',
     ]
 
     ignored_dirs = [
-        default_baked_project
-        ]
-
-    abs_expected_dirs = [os.path.join(default_baked_project, d) for
-                            d in expected_dirs]
+        str(default_baked_project)
+    ]
 
+    abs_expected_dirs = [str(default_baked_project / d) for d in expected_dirs]
     abs_dirs, _, _ = list(zip(*os.walk(default_baked_project)))
-
     assert len(set(abs_expected_dirs + ignored_dirs) - set(abs_dirs)) == 0
 
 
@@ -106,5 +99,4 @@ def no_curlies(filepath):
     ]
 
     template_strings_in_file = [s in data for s in template_strings]
-
     return not any(template_strings_in_file)