Deal with empty %changelog when converting

Fixes: #390
Related: rhbz#2448062

Signed-off-by: Nils Philippsen <nils@redhat.com>

Author: nphilipp

rpmautospec/subcommands/convert.py

@@ -168,8 +168,8 @@ def convert_to_autochangelog(self):
             )
 
         lineno = changelog_lines[0] + 1
-        if autochangelog_re.match(self.spec_lines[lineno]):
-            log.warning(f"'{self.specfile}' already uses %autochangelog")
+        if lineno < len(self.spec_lines) and autochangelog_re.match(self.spec_lines[lineno]):
+            log.warning("'%s' already uses %%autochangelog", self.specfile)
             return
         self.changelog_lines = [line.rstrip() for line in self.spec_lines[lineno:]]
         while self.changelog_lines and not self.changelog_lines[-1]:

tests/rpmautospec/subcommands/test_convert.py

@@ -213,20 +213,22 @@ def test_autorelease_invalid(specfile, expected):
 
 
 @pytest.mark.parametrize(
-    "changelog",
+    "changelog, is_empty",
     [
-        "%changelog\n- log line",
-        "%ChAnGeLoG\n- log line      ",  # trailing whitespace here
-        "%changelog\n- log line\n\n\n",  # trailing newlines here
+        ("%changelog\n- log line", False),
+        ("%ChAnGeLoG\n- log line      ", False),  # trailing whitespace here
+        ("%changelog\n- log line\n\n\n", False),  # trailing newlines here
+        ("%changelog", True),  # empty changelog, only a single newline character
     ],
     ids=[
         "regular",
         "case+whitespace",
         "regular+newlines",
+        "empty",
     ],
-    indirect=True,
+    indirect=("changelog",),
 )
-def test_autochangelog(specfile):
+def test_autochangelog(is_empty, specfile):
     assert autochangelog_re.search(specfile.read_text()) is None
 
     converter = convert.PkgConverter(specfile)
@@ -237,7 +239,10 @@ def test_autochangelog(specfile):
     assert autochangelog_re.search(specfile.read_text()) is not None
     changelog = specfile.parent / "changelog"
     assert changelog.exists()
-    assert changelog.read_text() == "- log line\n"
+    if is_empty:
+        assert changelog.read_text() == "\n"
+    else:
+        assert changelog.read_text() == "- log line\n"
 
 
 def test_autochangelog_already_converted(specfile, caplog):