Remove obsolete gpg version utils

The gpg utility functions `is_version_fully_supported` and
`get_version`, where used in in-toto tests to case-handle different
gpg versions. With in-toto/in-toto#190 this is no longer needed.
See most notably:
in-toto/in-toto@28ba993
in-toto/in-toto@c3a40b8

To reduce the API surface and maintenance burden this commit
removes those functions.

Signed-off-by: Lukas Puehringer <lukas.puehringer@nyu.edu>

securesystemslib/gpg/util.py

@@ -15,9 +15,7 @@
   general-purpose utilities for binary data handling and pgp data parsing
 """
 import binascii
-import dataclasses
 import logging
-import re
 import struct
 
 CRYPTO = True
@@ -29,7 +27,7 @@
     CRYPTO = False
 
 # pylint: disable=wrong-import-position
-from securesystemslib import exceptions, process
+from securesystemslib import exceptions
 from securesystemslib.gpg import constants
 from securesystemslib.gpg.exceptions import PacketParsingError
 
@@ -308,110 +306,6 @@ def parse_subpackets(data):
     return parsed_subpackets
 
 
-@dataclasses.dataclass(order=True)
-class Version:
-    """A version of GPG."""
-
-    major: int
-    minor: int
-    patch: int
-
-    VERSION_RE = re.compile(r"(\d)\.(\d)\.(\d+)")
-    EXAMPLE = "1.3.22"
-
-    @classmethod
-    def from_string(cls, value: str) -> "Version":
-        """
-        <Purpose>
-          Parses `value` as a `Version`.
-
-          Expects a version in the format `major.minor.patch`. `major` and `minor`
-          must be one-digit numbers; `patch` can be any integer.
-
-        <Arguments>
-          value:
-                  The version string to parse.
-
-        <Exceptions>
-          ValueError:
-                  If the version string is invalid.
-
-        <Returns>
-          Version
-        """
-        match = cls.VERSION_RE.fullmatch(value)
-        if not match:
-            raise ValueError(
-                f"Invalid version number '{value}'; "
-                f"expected MAJOR.MINOR.PATCH (e.g., '{cls.EXAMPLE}')"
-            )
-        major, minor, patch = map(int, match.groups())
-        return cls(major, minor, patch)
-
-    def __str__(self):
-        return f"{self.major}.{self.minor}.{self.patch}"
-
-
-def get_version() -> Version:
-    """
-    <Purpose>
-      Uses `gpg2 --version` to get the version info of the installed gpg2
-      and extracts and returns the version number.
-
-      The executed base command is defined in constants.gpg_version_command.
-
-    <Exceptions>
-      securesystemslib.exceptions.UnsupportedLibraryError:
-              If the gpg command is not available
-
-    <Side Effects>
-      Executes a command: constants.gpg_version_command.
-
-    <Returns>
-      Version of GPG.
-
-    """
-    if not constants.have_gpg():  # pragma: no cover
-        raise exceptions.UnsupportedLibraryError(constants.NO_GPG_MSG)
-
-    command = constants.gpg_version_command()
-    gpg_process = process.run(
-        command,
-        stdout=process.PIPE,
-        stderr=process.PIPE,
-        universal_newlines=True,
-    )
-
-    full_version_info = gpg_process.stdout
-    try:
-        match = Version.VERSION_RE.search(full_version_info)
-        if not match:
-            raise ValueError(
-                f"Couldn't find version number (ex. '{Version.EXAMPLE}') "
-                f"in the output of `{command}`:\n" + full_version_info
-            )
-        version = Version.from_string(match.group(0))
-    except ValueError as err:
-        raise exceptions.UnsupportedLibraryError(constants.NO_GPG_MSG) from err
-
-    return version
-
-
-def is_version_fully_supported():
-    """
-    <Purpose>
-      Compares the version of installed gpg2 with the minimal fully supported
-      gpg2 version (2.1.0).
-
-    <Returns>
-      True if the version returned by `get_version` is greater-equal
-      constants.FULLY_SUPPORTED_MIN_VERSION, False otherwise.
-
-    """
-    min_version = constants.FULLY_SUPPORTED_MIN_VERSION
-    return get_version() >= Version.from_string(min_version)
-
-
 def get_hashing_class(hash_algorithm_id):
     """
     <Purpose>

tests/test_gpg.py

@@ -33,7 +33,7 @@
 from cryptography.hazmat import backends
 from cryptography.hazmat.primitives import serialization
 
-from securesystemslib import exceptions, process
+from securesystemslib import process
 from securesystemslib.formats import ANY_PUBKEY_DICT_SCHEMA, GPG_PUBKEY_SCHEMA
 from securesystemslib.gpg.common import (
     _assign_certified_key_info,
@@ -72,10 +72,7 @@
 )
 from securesystemslib.gpg.rsa import create_pubkey as rsa_create_pubkey
 from securesystemslib.gpg.util import (
-    Version,
     get_hashing_class,
-    get_version,
-    is_version_fully_supported,
     parse_packet_header,
     parse_subpacket_header,
 )
@@ -100,19 +97,6 @@ def ignore_not_found_error(
 class TestUtil(unittest.TestCase):
     """Test util functions."""
 
-    def test_version_utils_return_types(self):
-        """Run dummy tests for coverage."""
-        self.assertTrue(isinstance(get_version(), Version))
-        self.assertTrue(isinstance(is_version_fully_supported(), bool))
-
-    def test_version_utils_error(self):
-        """Run dummy tests for coverage."""
-        with patch(
-            "securesystemslib.gpg.constants.have_gpg", return_value=False
-        ):
-            with self.assertRaises(exceptions.UnsupportedLibraryError):
-                get_version()
-
     def test_get_hashing_class(self):
         # Assert return expected hashing class
         expected_hashing_class = [hashing.SHA1, hashing.SHA256, hashing.SHA512]
@@ -947,32 +931,5 @@ def test_verify_short_signature(self):
         self.assertTrue(verify_signature(signature, key, test_data))
 
 
-class TestVersion(unittest.TestCase):
-    """Tests for the Version utility class."""
-
-    def test_version_roundtrip_string(self):
-        """Version parses and formats strings correctly."""
-        for value, expected in [
-            ("1.3.0", Version(1, 3, 0)),
-            ("1.3.1", Version(1, 3, 1)),
-            ("1.3.22", Version(1, 3, 22)),
-        ]:
-            self.assertEqual(Version.from_string(value), expected)
-            self.assertEqual(str(expected), value)
-
-    def test_version_from_string_invalid(self):
-        """Version.from_string rejects invalid inputs."""
-        for value in [
-            "1.3",
-            "1.33.0",
-            "1.3.-1",
-            "1.3.1a",
-        ]:
-            with self.assertRaises(
-                ValueError, msg=f"expected error for input '{value}'"
-            ):
-                Version.from_string(value)
-
-
 if __name__ == "__main__":
     unittest.main()