[test] One class contain one test method per file

Instead of one method with one subtest per file

Closes #92

test/test_chordpro/test_parser.py

@@ -16,22 +16,15 @@ LANGUAGES = {
     'sgc': 'chordpro',
 }
 
-class TestParsingRendering(unittest.TestCase):
+class FileTestMeta(type):
-    """Test parsing and rendering"""
+    """Metaclass that creates on-the-fly test function according to files.
 
-    maxDiff = None
+    See the :class:`FileTest` documentation for more information.
+    """
 
-    def test_all(self):
+    def __init__(cls, name, bases, nmspc):
-        """Test of chorpro parser, and several renderers.
+        super().__init__(name, bases, nmspc)
 
-        For any given `foo.source`, it is parsed as a chordpro file, and
-        should be rendered as `foo.sgc` with the chordpro renderer, and
-        `foo.tex` with the latex renderer.
-        """
-        config = DEFAULT_CONFIG.copy()
-        config.update({
-            'encoding': 'utf8',
-            })
         for source in sorted(glob.glob(os.path.join(
                 os.path.dirname(__file__),
                 '*.source',
@@ -41,15 +34,47 @@ class TestParsingRendering(unittest.TestCase):
                 destname = "{}.{}".format(base, dest)
                 if not os.path.exists(destname):
                     continue
+                setattr(
+                    cls,
+                    "test_{}_{}".format(os.path.basename(base), dest),
+                    cls._create_test(base, dest),
+                    )
+
+    @staticmethod
+    def _create_test(base, dest):
+        """Return a function testing that `base` compilation in `dest` format.
+        """
+
+        def test_parse_render(self):
+            """Test that `base` is correctly parsed and rendered."""
+            if base is None or dest is None:
+                return
+            destname = "{}.{}".format(base, dest)
             with open(destname, 'r', encoding='utf8') as expectfile:
                 chordproname = "{}.source".format(base)
-                    config['filename'] = chordproname
                 with disable_logging():
-                        with self.subTest(base=os.path.basename(base), format=dest):
                     self.assertMultiLineEqual(
-                                ChordproSong(None, chordproname, config).render(
+                        ChordproSong(None, chordproname, DEFAULT_CONFIG).render(
                             output=chordproname,
                             output_format=LANGUAGES[dest],
                             ).strip(),
                         expectfile.read().strip(),
                         )
+
+        test_parse_render.__doc__ = (
+            "Test that '{base}' is correctly parsed and rendererd into '{format}' format."
+            ).format(base=os.path.basename(base), format=dest)
+        return test_parse_render
+
+class FileTest(unittest.TestCase, metaclass=FileTestMeta):
+    """Test of chorpro parser, and several renderers.
+
+    For any given `foo.source`, it is parsed as a chordpro file, and should be
+    rendered as `foo.sgc` with the chordpro renderer, and `foo.tex` with the
+    latex renderer.
+
+    This class does nothing by itself, but its metaclass populates it with test
+    methods testing parser and renderers.
+    """
+
+    maxDiff = None