fix!: drop support for Python 2.7 (#43)

Drop use of 'six'

Drop use of 'mock' shim module

Closes #42.

setup.py

@@ -40,19 +40,12 @@
     entry_points={"console_scripts": scripts},
     platforms="Posix; MacOS X; Windows",
     include_package_data=True,
-    install_requires=(
-        "google-auth >= 0.4.0",
-        "six>=1.9.0",
-        "click>=7.0.0",
-        "packaging>=19.0",
-    ),
-    python_requires=">=2.7,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*",
+    install_requires=("google-auth >= 0.4.0", "click>=7.0.0", "packaging>=19.0"),
+    python_requires=">=3.6",
     classifiers=[
         "Development Status :: 4 - Beta",
         "Intended Audience :: Developers",
         "Operating System :: OS Independent",
-        "Programming Language :: Python :: 2",
-        "Programming Language :: Python :: 2.7",
         "Programming Language :: Python :: 3",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",

test_utils/imports.py

@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import mock
-import six
+import builtins
+from unittest import mock
 
 
 def maybe_fail_import(predicate):
@@ -28,11 +28,11 @@ def maybe_fail_import(predicate):
     Returns:
         A mock patcher object that can be used to enable patched import behavior.
     """
-    orig_import = six.moves.builtins.__import__
+    orig_import = builtins.__import__
 
     def custom_import(name, globals=None, locals=None, fromlist=(), level=0):
         if predicate(name, globals, locals, fromlist, level):
             raise ImportError
         return orig_import(name, globals, locals, fromlist, level)
 
-    return mock.patch.object(six.moves.builtins, "__import__", new=custom_import)
+    return mock.patch.object(builtins, "__import__", new=custom_import)

test_utils/retry.py

@@ -12,10 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import functools
 import time
 
-import six
-
 MAX_TRIES = 4
 DELAY = 1
 BACKOFF = 2
@@ -51,7 +50,7 @@ def __init__(self, max_tries=MAX_TRIES, delay=DELAY, backoff=BACKOFF, logger=Non
         self.max_tries = max_tries
         self.delay = delay
         self.backoff = backoff
-        self.logger = logger.warning if logger else six.print_
+        self.logger = logger.warning if logger else print
 
 
 class RetryErrors(RetryBase):
@@ -93,7 +92,7 @@ def __init__(
         self.error_predicate = error_predicate
 
     def __call__(self, to_wrap):
-        @six.wraps(to_wrap)
+        @functools.wraps(to_wrap)
         def wrapped_function(*args, **kwargs):
             tries = 0
             while tries < self.max_tries:
@@ -151,7 +150,7 @@ def __init__(
         self.result_predicate = result_predicate
 
     def __call__(self, to_wrap):
-        @six.wraps(to_wrap)
+        @functools.wraps(to_wrap)
         def wrapped_function(*args, **kwargs):
             tries = 0
             while tries < self.max_tries:
@@ -208,7 +207,7 @@ def __init__(
     def __call__(self, to_wrap):
         instance = to_wrap.__self__  # only instance methods allowed
 
-        @six.wraps(to_wrap)
+        @functools.wraps(to_wrap)
         def wrapped_function(*args, **kwargs):
             tries = 0
             while tries < self.max_tries:

testing/constraints-3.6.txt

@@ -1,5 +1,4 @@
 click==7.0.0
 google-auth==0.4.0
 packaging==19.0
-six==1.9.0
-colorlog==3.0.0
+colorlog==3.0.0

tests/unit/resources/bad_package/setup.py

@@ -18,7 +18,7 @@
 requirements = [
     "requests",  # no lower bound
     "packaging>=14.0, !=15.0, <22.0.0",  # too complex for tool
-    "six<2.0.0",  # no lower bound
+    "wheel<0.36.0",
     "click==7.0.0",
 ]
 

tests/unit/resources/good_package/setup.py

@@ -21,7 +21,7 @@
 requirements = [
     "requests>=1.0.0",
     "packaging>=14.0, <22.0.0",
-    "six<2.0.0, >=1.0.0",
+    "wheel<0.36.0, >=0.35.0",
     "click==7.0.0",
 ]
 

tests/unit/test_lower_bound_checker.py

@@ -88,15 +88,15 @@ def test_update_constraints():
 
         output = constraints_path.read_text().split("\n")
 
-        assert output == ["click==7.0.0", "grpcio==1.0.0", "packaging==14.0", "requests==1.0.0", "six==1.0.0",]
+        assert output == ["click==7.0.0", "grpcio==1.0.0", "packaging==14.0", "requests==1.0.0", "wheel==0.35.0",]
 
 
 
 def test_update_constraints_overwrites_existing_file():
     constraints = [
         "requests==1.0.0",
         "packaging==13.0",
-        "six==1.6.0",
+        "wheel==0.36.0",
         "click==5.0.0",
     ]
     with constraints_file(constraints) as c:
@@ -107,14 +107,14 @@ def test_update_constraints_overwrites_existing_file():
         assert result.exit_code == 0
 
         output = c.read_text().split("\n")
-        assert output == ["click==7.0.0", "grpcio==1.0.0", "packaging==14.0", "requests==1.0.0", "six==1.0.0",
+        assert output == ["click==7.0.0", "grpcio==1.0.0", "packaging==14.0", "requests==1.0.0", "wheel==0.35.0",
         ]
 
 def test_update_constraints_with_setup_py_missing_lower_bounds():
     constraints = [
         "requests==1.0.0",
         "packaging==14.0",
-        "six==1.0.0",
+        "wheel==0.35.0",
         "click==7.0.0",
     ]
     with constraints_file(constraints) as c:
@@ -126,15 +126,15 @@ def test_update_constraints_with_setup_py_missing_lower_bounds():
     assert "setup.py is missing explicit lower bounds" in result.output
 
     invalid_pkg_list = parse_error_msg(result.output)
-    assert set(invalid_pkg_list) == {"requests", "packaging", "six"}
+    assert set(invalid_pkg_list) == {"requests", "packaging", "wheel"}
 
 
 
 def test_check():
     constraints = [
         "requests==1.0.0",
         "packaging==14.0",
-        "six==1.0.0",
+        "wheel==0.35.0",
         "click==7.0.0",
         "grpcio==1.0.0"
     ]
@@ -150,7 +150,7 @@ def test_update_constraints_with_extra_constraints():
     constraints = [
         "requests==1.0.0",
         "packaging==14.0",
-        "six==1.0.0",
+        "wheel==0.35.0",
         "click==7.0.0",
         "grpcio==1.0.0",
         "pytest==6.0.0",  # additional requirement
@@ -182,7 +182,7 @@ def test_check_with_constraints_file_invalid_pins():
     constraints = [
         "requests==1.0.0",
         "packaging==14.0",
-        "six==1.0.0, <2.0.0dev",  # should be ==
+        "wheel==1.0.0, <2.0.0dev",  # should be ==
         "click>=7.0.0",  # should be ==
     ]
     with constraints_file(constraints) as c:
@@ -194,14 +194,14 @@ def test_check_with_constraints_file_invalid_pins():
 
     invalid_pkg_list = parse_error_msg(result.output)
 
-    assert set(invalid_pkg_list) == {"six", "click"}
+    assert set(invalid_pkg_list) == {"wheel", "click"}
 
 
 def test_check_with_constraints_file_missing_packages():
     constraints = [
         "requests==1.0.0",
         "packaging==14.0",
-        # missing 'six' and 'click' and extra 'grpcio'
+        # missing 'wheel' and 'click' and extra 'grpcio'
     ]
     with constraints_file(constraints) as c:
         result = RUNNER.invoke(
@@ -211,14 +211,14 @@ def test_check_with_constraints_file_missing_packages():
     assert result.exit_code == 2
 
     invalid_pkg_list = parse_error_msg(result.output)
-    assert set(invalid_pkg_list) == {"six", "click", "grpcio"}
+    assert set(invalid_pkg_list) == {"wheel", "click", "grpcio"}
 
 
 def test_check_with_constraints_file_different_versions():
     constraints = [
         "requests==1.2.0",  # setup.py has 1.0.0
         "packaging==14.1",  # setup.py has 14.0
-        "six==1.4.0",  # setup.py has 1.0.0
+        "wheel==0.36.0",  # setup.py has 0.35.0
         "click==7.0.0",
         "grpcio==1.0.0"
     ]
@@ -230,14 +230,14 @@ def test_check_with_constraints_file_different_versions():
     assert result.exit_code == 2
 
     invalid_pkg_list = parse_diff_versions_error_msg(result.output)
-    assert set(invalid_pkg_list) == {"requests", "packaging", "six"}
+    assert set(invalid_pkg_list) == {"requests", "packaging", "wheel"}
 
 
 def test_check_with_setup_py_missing_lower_bounds():
     constraints = [
         "requests==1.0.0",
         "packaging==14.0",
-        "six==1.0.0",
+        "wheel==1.0.0",
         "click==7.0.0",
     ]
     with constraints_file(constraints) as c:
@@ -248,4 +248,4 @@ def test_check_with_setup_py_missing_lower_bounds():
     assert result.exit_code == 2
 
     invalid_pkg_list = parse_error_msg(result.output)
-    assert set(invalid_pkg_list) == {"requests", "packaging", "six"}
+    assert set(invalid_pkg_list) == {"requests", "packaging", "wheel"}