Make Song.parse() take the file content instead of a file name

src/chordpro/base.py

@@ -190,16 +190,16 @@ class Song(object):
     def __init__(self, filename=None):
         self.filename = filename
         if self.filename:
-            self.parse(self.filename)
+            with open(filename) as song_file:
+                self.parse(song_file.read())
 
-    def parse(self, filename):
+    def parse(self, text):
         self.metadata = Metadata()
         self.verses = []
         self.verse_order = []
-        with open(filename) as song_file:
         is_verse = False
         current_verse = None
-            for line_number, line in enumerate(song_file):
+        for line_number, line in enumerate(text.splitlines()):
             if Directive.is_directive(line):
                 self.metadata.add(Directive(line))
             elif Verse.is_start_of_verse(line):