Fix text carrier-over between pages. Fix tests.

1. Fixed tests by including newlines from extracted documents
2. Added test to illustrate merge bug from commit
43614f2 in which uncleared buffer
carries text between pages
3. Added clearing of buffer that also addresses issue #21 in the prior
codebase

src/slate/classes.py

@@ -41,6 +41,7 @@ def process_page(self, page):
         else:
             ctm = (1,0,0,1, -x0,-y0)
         self.device.outfp.seek(0)
+        self.device.outfp.truncate(0)
         self.device.begin_page(page, ctm)
         self.render_contents(page.resources, page.contents, ctm=ctm)
         self.device.end_page(page)

src/slate/unittests.py

@@ -10,7 +10,10 @@ def setUp(self):
             self.passwd = PDF(f, 'a')
 
     def test_basic(self):
-        assert self.doc[0] == 'This is a test.\x0c'
+        assert self.doc[0] == 'This is a test.\n\n\x0c'
+
+    def test_no_text_carry_over(self):
+        assert self.doc[1] == '\x0c'
 
     def test_metadata_extraction(self):
         assert self.doc.metadata
@@ -22,7 +25,7 @@ def test_text_method_unclean(self):
         assert '\x0c' in self.doc.text(clean=0)
 
     def test_password(self):
-        assert self.passwd[0] == "Chamber of secrets.\x0c"
+        assert self.passwd[0] == "Chamber of secrets.\n\n\x0c"
 
 if __name__ == '__main__':
     unittest.main()