test(python): use constraints files to check dependency lower bounds (#56)

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        repository, or by version upgrades to tools such as linters.

* chore(deps): update precommit hook pycqa/flake8 to v3.9.0

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [pycqa/flake8](https://gitlab.com/pycqa/flake8) | repository | minor | `3.8.4` -> `3.9.0` |

---

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<summary>pycqa/flake8</summary>

### [`v3.9.0`](https://gitlab.com/pycqa/flake8/compare/3.8.4...3.9.0)

[Compare Source](https://gitlab.com/pycqa/flake8/compare/3.8.4...3.9.0)

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Source-Author: WhiteSource Renovate <[email protected]>
Source-Date: Tue Mar 23 17:38:03 2021 +0100
Source-Repo: googleapis/synthtool
Source-Sha: f5c5904fb0c6aa3b3730eadf4e5a4485afc65726
Source-Link: googleapis/synthtool@f5c5904

* test(python): use constraints files to check dependency lower bounds

Use a constraints file when installing dependencies for system and unit tests nox sessions.

https://pip.pypa.io/en/stable/user_guide/#constraints-files
> Constraints files are requirements files that **only control which version of a requirement is installed, not whether it is installed or not**. Their syntax and contents is nearly identical to Requirements Files. There is one key difference: Including a package in a constraints file does not trigger installation of the package.

```
testing
├── constraints-3.10.txt
├── constraints-3.11.txt
├── constraints-3.6.txt
├── constraints-3.7.txt
├── constraints-3.8.txt
└── constraints-3.9.txt
```

Going forward, one constraints file (currently 3.6) will be populated with every library requirement and extra listed in the `setup.py`. The constraints file will pin each requirement to the lower bound. This ensures that library maintainers will see test failures if they forget to update a lower bound on a dependency.

See googleapis/python-bigquery#263 for an example

Source-Author: Bu Sun Kim <[email protected]>
Source-Date: Tue Mar 23 10:52:02 2021 -0600
Source-Repo: googleapis/synthtool
Source-Sha: 86ed43d4f56e6404d068e62e497029018879c771
Source-Link: googleapis/synthtool@86ed43d

* fix: add version range for grpc-google-iam-v1

* chore: exclude tarfile

Co-authored-by: Tim Swast <[email protected]>
Co-authored-by: Bu Sun Kim <[email protected]>

Author: 3 people

.pre-commit-config.yaml

@@ -12,6 +12,6 @@ repos:
     hooks:
     - id: black
 -   repo: https://gitlab.com/pycqa/flake8
-    rev: 3.8.4
+    rev: 3.9.0
     hooks:
     - id: flake8

noxfile.py

@@ -18,6 +18,7 @@
 
 from __future__ import absolute_import
 import os
+import pathlib
 import shutil
 
 import nox
@@ -30,6 +31,8 @@
 SYSTEM_TEST_PYTHON_VERSIONS = ["3.8"]
 UNIT_TEST_PYTHON_VERSIONS = ["3.6", "3.7", "3.8", "3.9"]
 
+CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
+
 # 'docfx' is excluded since it only needs to run in 'docs-presubmit'
 nox.options.sessions = [
     "unit",
@@ -84,13 +87,15 @@ def lint_setup_py(session):
 
 def default(session):
     # Install all test dependencies, then install this package in-place.
-    session.install("asyncmock", "pytest-asyncio")
 
-    session.install(
-        "mock", "pytest", "pytest-cov",
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
+    session.install("asyncmock", "pytest-asyncio", "-c", constraints_path)
 
-    session.install("-e", ".")
+    session.install("mock", "pytest", "pytest-cov", "-c", constraints_path)
+
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the unit tests.
     session.run(
@@ -117,6 +122,9 @@ def unit(session):
 @nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)
 def system(session):
     """Run the system test suite."""
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
+    )
     system_test_path = os.path.join("tests", "system.py")
     system_test_folder_path = os.path.join("tests", "system")
 
@@ -141,10 +149,8 @@ def system(session):
 
     # Install all test dependencies, then install this package into the
     # virtualenv's dist-packages.
-    session.install(
-        "mock", "pytest", "google-cloud-testutils",
-    )
-    session.install("-e", ".")
+    session.install("mock", "pytest", "google-cloud-testutils", "-c", constraints_path)
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the system tests.
     if system_test_exists:

setup.py

@@ -40,13 +40,11 @@
     platforms="Posix; MacOS X; Windows",
     include_package_data=True,
     install_requires=(
-        "google-api-core >= 1.21.0, < 2.0.0dev",
+        "google-api-core >= 1.22.2, < 2.0.0dev",
         "proto-plus >= 1.4.0",
-        "grpc-google-iam-v1",
-        "libcst >= 0.2.5",
+        "grpc-google-iam-v1 >= 0.12.3, < 0.13.0dev",
     ),
     python_requires=">=3.6",
-    scripts=["scripts/fixup_keywords.py"],
     classifiers=[
         "Development Status :: 4 - Beta",
         "Intended Audience :: Developers",

synth.metadata

@@ -19,14 +19,14 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "79c8dd7ee768292f933012d3a69a5b4676404cda"
+        "sha": "86ed43d4f56e6404d068e62e497029018879c771"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "79c8dd7ee768292f933012d3a69a5b4676404cda"
+        "sha": "86ed43d4f56e6404d068e62e497029018879c771"
       }
     }
   ],
@@ -98,6 +98,7 @@
     "CONTRIBUTING.rst",
     "LICENSE",
     "MANIFEST.in",
+    "bigquery-connection-v1-py.tar.gz",
     "docs/_static/custom.css",
     "docs/_templates/layout.html",
     "docs/bigquery_connection_v1/connection_service.rst",

synth.py

@@ -31,7 +31,7 @@
     bazel_target=f"//google/cloud/bigquery/connection/v1:bigquery-connection-v1-py"
 )
 
-s.move(library, excludes=["setup.py", "README.rst", "docs/index.rst"])
+s.move(library, excludes=["setup.py", "README.rst", "docs/index.rst", "*.tar.gz"])
 
 # ----------------------------------------------------------------------------
 # Add templated files

testing/constraints-3.6.txt

@@ -5,7 +5,6 @@
 #
 # e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have foo==1.14.0
-google-api-core==1.21.0
+google-api-core==1.22.2
 proto-plus==1.4.0
-grpc-google-iam-v1==0.9.0
-libcst==0.2.5
+grpc-google-iam-v1==0.12.3