feat: Add support to finding previous version from tags if not using …

…commit messages (#68)

* feat: Be a bit more forgiving to find previous tags

Now grabs the previous version from tag names if it can't find it in the commit

* quantifiedcode and flake8 fixes

* Update cli.py

* Switch to ImproperConfigurationError

semantic_release/cli.py

@@ -87,8 +87,13 @@ def changelog(**kwargs):
     Generates the changelog since the last release.
     """
     current_version = get_current_version()
-    log = generate_changelog(
-        get_previous_version(current_version), current_version)
+    if current_version is None:
+        raise ImproperConfigurationError("Unable to get the current version."
+                        " Make sure semantic_release.version_variable "
+                        "is setup correctly")
+    previous_version = get_previous_version(current_version)
+
+    log = generate_changelog(previous_version,  current_version)
     for section in CHANGELOG_SECTIONS:
         if not log[section]:
             continue

semantic_release/history/__init__.py

@@ -69,8 +69,11 @@ def get_previous_version(version):
             continue
 
         if found_version:
-            if re.match(r'v?\d+.\d+.\d+', commit_message):
-                return commit_message.replace('v', '').strip()
+            matches = re.match(r'v?(\d+.\d+.\d+)', commit_message)
+            if matches:
+                return matches.group(1).strip()
+
+    return get_last_version([version, 'v{}'.format(version)])
 
 
 def set_new_version(new_version):

semantic_release/vcs_helpers.py

@@ -1,6 +1,6 @@
 import re
 
-from git import GitCommandError, NoSuchPathError, Repo
+from git import GitCommandError, TagObject, NoSuchPathError, Repo
 
 from .errors import GitError
 from .settings import config
@@ -23,15 +23,23 @@ def get_commit_log(from_rev=None):
         yield (commit.hexsha, commit.message)
 
 
-def get_last_version():
+def get_last_version(skip_tags=None):
     """
     return last version from repo tags
 
     :return: a string contains version number
     """
+    skip_tags = skip_tags or []
 
-    for i in sorted(repo.tags, key=lambda x: x.commit.committed_date, reverse=True):
+    def version_finder(x):
+        if isinstance(x.commit, TagObject):
+            return x.tag.tagged_date
+        return x.commit.committed_date
+
+    for i in sorted(repo.tags, reverse=True, key=version_finder):
         if re.match('v\d+\.\d+\.\d+', i.name):
+            if i.name in skip_tags:
+                continue
             return i.name[1:]