utils: make tidy() also clean up the first section

iniparse/utils.py

@@ -19,12 +19,13 @@ def tidy(cfg: compat.RawConfigParser):
     if isinstance(cfg, compat.RawConfigParser):
         cfg = cfg.data
     cont = cfg._data.contents
-    i = 1
+    # start at 0 so that a section at the very top of the file is tidied too
+    i = 0
     while i < len(cont):
         if isinstance(cont[i], LineContainer):
             tidy_section(cont[i])
             i += 1
-        elif (isinstance(cont[i-1], EmptyLine) and
+        elif (i > 0 and isinstance(cont[i-1], EmptyLine) and
               isinstance(cont[i], EmptyLine)):
             del cont[i]
         else:

tests/test_tidy.py

@@ -232,3 +232,26 @@ def test_compat(self):
 
             c=3
             """))
+
+    def test_first_section_is_tidied(self):
+        """
+        :id: dce50a4b-cb18-4bf7-bf7a-d0260cac1162
+        :title: tidy() cleans up a section at the start of the file
+        :description:
+            Verifies that tidy() collapses consecutive empty lines in the
+            first section even when the file starts directly with a
+            section header.
+        :tags: Tier 2
+        :steps:
+            1. Parse a file starting with `[a]` whose options are separated
+               by several empty lines, followed by a similar section `[b]`.
+            2. Call tidy() and render the configuration.
+        :expectedresults:
+            1. File is parsed.
+            2. Both sections contain only single empty lines.
+        """
+        cfg = INIConfig(StringIO('[a]\nx = 1\n\n\n\ny = 2\n\n'
+                                 '[b]\nz = 3\n\n\n\nw = 4\n'))
+        tidy(cfg)
+        self.assertEqual(str(cfg), '[a]\nx = 1\n\ny = 2\n\n'
+                                   '[b]\nz = 3\n\nw = 4\n')