feat: add lower bound checker

noxfile.py

@@ -14,17 +14,28 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Generated by synthtool. DO NOT EDIT!
 
 from __future__ import absolute_import
 import os
+import pathlib
 import shutil
 
 import nox
 
+# 'update_lower_bounds' is excluded 
+nox.options.sessions = [
+    "lint",
+    "blacken",
+    "lint_setup_py",
+    "unit",
+    "check_lower_bounds"
+]
+
 
 BLACK_VERSION = "black==19.3b0"
 BLACK_PATHS = ["test_utils", "setup.py"]
+CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
+
 
 @nox.session(python="3.7")
 def lint(session):
@@ -35,9 +46,7 @@ def lint(session):
     """
     session.install("flake8", BLACK_VERSION)
     session.run(
-        "black",
-        "--check",
-        *BLACK_PATHS,
+        "black", "--check", *BLACK_PATHS,
     )
     session.run("flake8", *BLACK_PATHS)
 
@@ -54,13 +63,60 @@ def blacken(session):
     """
     session.install(BLACK_VERSION)
     session.run(
-        "black",
-        *BLACK_PATHS,
+        "black", *BLACK_PATHS,
     )
 
 
 @nox.session(python="3.7")
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
     session.install("docutils", "pygments")
-    session.run("python", "setup.py", "check", "--restructuredtext", "--strict")
+    session.run("python", "setup.py", "check", "--restructuredtext", "--strict")
+
+
+@nox.session(python=["3.6", "3.7", "3.8", "3.9"])
+def unit(session):
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
+    )
+
+    # Install two fake packages for the lower-bound-checker tests
+    session.install("-e", "tests/unit/resources/good_package", "tests/unit/resources/bad_package")
+
+    session.install("pytest")
+    session.install("-e", ".", "-c", constraints_path)
+
+    # Run py.test against the unit tests.
+    session.run(
+        "py.test",
+        "--quiet",
+        os.path.join("tests", "unit"),
+        *session.posargs,
+    )
+
+@nox.session(python="3.8")
+def check_lower_bounds(session):
+    """Check lower bounds in setup.py are reflected in constraints file"""
+    session.install(".")
+    session.run(
+        "lower-bound-checker",
+        "check",
+        "--package-name",
+        "google-cloud-testutils",
+        "--constraints-file",
+        "testing/constraints-3.6.txt",
+    )
+
+
+@nox.session(python="3.8")
+def update_lower_bounds(session):
+    """Update lower bounds in constraints.txt to match setup.py"""
+    session.install(".")
+    session.run(
+        "lower-bound-checker",
+        "update",
+        "--package-name",
+        "google-cloud-testutils",
+        "--constraints-file",
+        "testing/constraints-3.6.txt",
+    )

setup.py

@@ -24,6 +24,10 @@
 with io.open(readme_filename, encoding="utf-8") as readme_file:
     readme = readme_file.read()
 
+scripts = (
+    ["lower-bound-checker=test_utils.lower_bound_checker.lower_bound_checker:main"],
+)
+
 setuptools.setup(
     name="google-cloud-testutils",
     version=version,
@@ -33,9 +37,15 @@
     license="Apache 2.0",
     url="https://github.com/googleapis/python-test-utils",
     packages=setuptools.PEP420PackageFinder.find(),
+    entry_points={"console_scripts": scripts},
     platforms="Posix; MacOS X; Windows",
     include_package_data=True,
-    install_requires=("google-auth >= 0.4.0", "six"),
+    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.*",
     classifiers=[
         "Development Status :: 4 - Beta",