feat(providers): add scm provider reading version from the last tag m…

…atching tag_format

Fixes #641

commitizen/providers.py

@@ -1,15 +1,18 @@
 from __future__ import annotations
 
 import json
+import re
 from abc import ABC, abstractmethod
 from pathlib import Path
-from typing import Any, ClassVar, cast
+from typing import Any, Callable, ClassVar, Optional, cast
 
 import importlib_metadata as metadata
 import tomlkit
+from packaging.version import VERSION_PATTERN, Version
 
 from commitizen.config.base_config import BaseConfig
 from commitizen.exceptions import VersionProviderUnknown
+from commitizen.git import get_tags
 
 ENTRYPOINT = "commitizen.provider"
 DEFAULT = "commitizen"
@@ -157,6 +160,60 @@ class ComposerProvider(JsonProvider):
     indent = 4
 
 
+class ScmProvider(VersionProvider):
+    """
+    A provider dedicated to be coupled with `setuptools-scm`
+    or any package manager `-scm` provider.
+
+    Version is fetched from git history (using `git describe`)
+    and does not need to be set back.
+    """
+
+    TAG_FORMAT_REGEXS = {
+        "$version": r"(?P<version>.+)",
+        "$major": r"(?P<major>\d+)",
+        "$minor": r"(?P<minor>\d+)",
+        "$patch": r"(?P<patch>\d+)",
+        "$prerelease": r"(?P<prerelease>\w+\d+)?",
+        "$devrelease": r"(?P<devrelease>\.?dev\d+)?",
+    }
+
+    def _tag_format_matcher(self) -> Callable[[str], Optional[str]]:
+        tag_format = self.config.settings.get("tag_format") or VERSION_PATTERN
+        for var, pattern in self.TAG_FORMAT_REGEXS.items():
+            tag_format = tag_format.replace(var, pattern)
+
+        regex = re.compile(f"^{tag_format}$", re.VERBOSE)
+
+        def matcher(tag: str) -> Optional[str]:
+            m = regex.match(tag)
+            if not m:
+                return None
+            elif "version" in m.groupdict():
+                return m.group("version")
+            elif "devrelease" in m.groupdict():
+                return "{major}.{minor}.{patch}{devrelease}".format(**m.groupdict())
+            elif "prerelease" in m.groupdict():
+                return "{major}.{minor}.{patch}{prerelease}".format(**m.groupdict())
+            elif "major" in m.groupdict():
+                return "{major}.{minor}.{patch}".format(**m.groupdict())
+            elif tag_format == VERSION_PATTERN:
+                return str(Version(tag))
+            return None
+
+        return matcher
+
+    def get_version(self) -> str:
+        matcher = self._tag_format_matcher()
+        return next(
+            (cast(str, matcher(t.name)) for t in get_tags() if matcher(t.name)), "0.0.0"
+        )
+
+    def set_version(self, version: str):
+        # Not necessary
+        pass
+
+
 def get_provider(config: BaseConfig) -> VersionProvider:
     """
     Get the version provider as defined in the configuration

docs/config.md

@@ -123,12 +123,16 @@ Commitizen provides some version providers for some well known formats:
 | name | description |
 | ---- | ----------- |
 | `commitizen` | Default version provider: Fetch and set version in commitizen config. |
+| `scm` | Fetch the version from git and does not need to set it back |
 | `pep621` | Get and set version from `pyproject.toml` `project.version` field |
 | `poetry` | Get and set version from `pyproject.toml` `tool.poetry.version` field |
 | `cargo` | Get and set version from `Cargo.toml` `project.version` field |
 | `npm` | Get and set version from `package.json` `project.version` field |
 | `composer` | Get and set version from `composer.json` `project.version` field |
 
+!!! note
+    The `scm` provider is meant to be used with `setuptools-scm` or any packager `*-scm` plugin.
+
 ### Custom version provider
 
 You can add you own version provider by extending `VersionProvider` and exposing it on the `commitizen.provider` entrypoint.

pyproject.toml

@@ -111,6 +111,7 @@ composer = "commitizen.providers:ComposerProvider"
 npm = "commitizen.providers:NpmProvider"
 pep621 = "commitizen.providers:Pep621Provider"
 poetry = "commitizen.providers:PoetryProvider"
+scm = "commitizen.providers:ScmProvider"
 
 [tool.isort]
 profile = "black"

tests/test_version_providers.py

@@ -3,7 +3,7 @@
 import os
 from pathlib import Path
 from textwrap import dedent
-from typing import TYPE_CHECKING, Iterator
+from typing import TYPE_CHECKING, Iterator, Optional
 
 import pytest
 
@@ -16,8 +16,10 @@
     NpmProvider,
     Pep621Provider,
     PoetryProvider,
+    ScmProvider,
     get_provider,
 )
+from tests.utils import create_file_and_commit, create_tag
 
 if TYPE_CHECKING:
     from pytest_mock import MockerFixture
@@ -185,3 +187,59 @@ def test_composer_provider(config: BaseConfig, chdir: Path):
         }
         """
     )
+
+
+@pytest.mark.parametrize(
+    "tag_format,tag,version",
+    (
+        (None, "0.1.0", "0.1.0"),
+        (None, "v0.1.0", "0.1.0"),
+        ("v$version", "v0.1.0", "0.1.0"),
+        ("version-$version", "version-0.1.0", "0.1.0"),
+        ("v$major.$minor.$patch", "v0.1.0", "0.1.0"),
+        ("v$minor.$major.$patch", "v1.0.0", "0.1.0"),
+        ("version-$major.$minor.$patch", "version-0.1.0", "0.1.0"),
+        ("v$minor.$major.$patch$prerelease", "v1.0.0rc1", "0.1.0rc1"),
+        ("v$minor.$major.$patch$prerelease$devrelease", "v1.0.0.dev0", "0.1.0.dev0"),
+    ),
+)
+@pytest.mark.usefixtures("tmp_git_project")
+def test_scm_provider(
+    config: BaseConfig, tag_format: Optional[str], tag: str, version: str
+):
+    create_file_and_commit("test: fake commit")
+    create_tag(tag)
+    create_file_and_commit("test: fake commit")
+    create_tag("should-not-match")
+
+    config.settings["version_provider"] = "scm"
+    config.settings["tag_format"] = tag_format
+
+    provider = get_provider(config)
+    assert isinstance(provider, ScmProvider)
+    assert provider.get_version() == version
+
+    # Should not fail on set_version()
+    provider.set_version("43.1")
+
+
+@pytest.mark.usefixtures("tmp_git_project")
+def test_scm_provider_default_without_matching_tag(config: BaseConfig):
+    create_file_and_commit("test: fake commit")
+    create_tag("should-not-match")
+    create_file_and_commit("test: fake commit")
+
+    config.settings["version_provider"] = "scm"
+
+    provider = get_provider(config)
+    assert isinstance(provider, ScmProvider)
+    assert provider.get_version() == "0.0.0"
+
+
+@pytest.mark.usefixtures("tmp_git_project")
+def test_scm_provider_default_without_commits_and_tags(config: BaseConfig):
+    config.settings["version_provider"] = "scm"
+
+    provider = get_provider(config)
+    assert isinstance(provider, ScmProvider)
+    assert provider.get_version() == "0.0.0"