feat(history): Add generate_changelog function

It generates a dict with changelog information to each of the given
section types.

semantic_release/history/logs.py

@@ -1,3 +1,4 @@
+import re
 from ..errors import UnknownCommitMessageStyle
 from ..settings import current_commit_parser
 from ..settings import config
@@ -9,6 +10,10 @@
     3: 'major',
 }
 
+CHANGELOG_SECTIONS = ['feature', 'fix', 'breaking', 'documentation']
+
+re_breaking = re.compile('BREAKING CHANGE: (.*)')
+
 
 def evaluate_version_bump(current_version, force=None):
     """
@@ -46,3 +51,33 @@ def evaluate_version_bump(current_version, force=None):
     if config.getboolean('semantic_release', 'patch_without_tag') and commit_count:
         bump = 'patch'
     return bump
+
+
+def generate_changelog(version):
+    """
+    Generates a changelog for the given version.
+
+    :param version: a version string
+    :return: a dict with different changelog sections
+    """
+
+    changes = {'feature': [], 'fix': [], 'documentation': [], 'refactor': [], 'breaking': []}
+
+    for commit_message in get_commit_log():
+        if version in commit_message:
+            break
+
+        try:
+            message = current_commit_parser()(commit_message)
+            changes[message[1]].append(message[3][0])
+
+            if message[3][1] and 'BREAKING CHANGE' in message[3][1]:
+                changes['breaking'].append(re_breaking.match(message[3][1]).group(1))
+
+            if message[3][2] and 'BREAKING CHANGE' in message[3][2]:
+                changes['breaking'].append(re_breaking.match(message[3][2]).group(1))
+
+        except UnknownCommitMessageStyle:
+            pass
+
+    return changes

tests/test_history.py

@@ -4,12 +4,17 @@
 from semantic_release.history import evaluate_version_bump, get_current_version, get_new_version
 
 from . import mock
+from semantic_release.history.logs import generate_changelog
 
 MAJOR = 'feat(x): Add super-feature\n\nBREAKING CHANGE: Uses super-feature as default instead of ' \
         'dull-feature.'
+MAJOR2 = 'feat(x): Add super-feature\n\nSome explanation\n\n' \
+         'BREAKING CHANGE: Uses super-feature as default instead of ' \
+         'dull-feature.'
 MINOR = 'feat(x): Add non-breaking super-feature'
 PATCH = 'fix(x): Fix bug in super-feature'
 NO_TAG = 'docs(x): Add documentation for super-feature'
+UNKNOWN_STYLE = 'random commits are the worst'
 
 ALL_KINDS_OF_COMMIT_MESSAGES = [MINOR, MAJOR, MINOR, PATCH]
 MINOR_AND_PATCH_COMMIT_MESSAGES = [MINOR, PATCH]
@@ -67,6 +72,29 @@ def test_should_return_none_without_commits(self):
         with mock.patch('semantic_release.history.config.getboolean', lambda *x: False):
             self.assertIsNone(evaluate_version_bump('1.1.0'))
 
+class GenerateChangelogTests(TestCase):
+
+    def test_should_generate_all_sections(self):
+        with mock.patch('semantic_release.history.logs.get_commit_log',
+                        lambda: ALL_KINDS_OF_COMMIT_MESSAGES + [MAJOR2, UNKNOWN_STYLE]):
+            changelog = generate_changelog('0.0.0')
+            self.assertIn('feature', changelog)
+            self.assertIn('fix', changelog)
+            self.assertIn('documentation', changelog)
+            self.assertIn('breaking', changelog)
+            self.assertGreater(len(changelog['feature']), 0)
+            self.assertGreater(len(changelog['fix']), 0)
+            self.assertGreater(len(changelog['breaking']), 0)
+
+    def test_should_only_read_until_given_version(self):
+        with mock.patch('semantic_release.history.logs.get_commit_log',
+                        lambda: MAJOR_LAST_RELEASE_MINOR_AFTER):
+            changelog = generate_changelog('1.1.0')
+            self.assertGreater(len(changelog['feature']), 0)
+            self.assertEqual(len(changelog['fix']), 0)
+            self.assertEqual(len(changelog['documentation']), 0)
+            self.assertEqual(len(changelog['breaking']), 0)
+
 
 class GetCurrentVersionTests(TestCase):
     def test_should_return_correct_version(self):