From d25ebcfef3f9817f7417927938be7d75910b7154 Mon Sep 17 00:00:00 2001
From: yoshi-automation <yoshi-automation@google.com>
Date: Thu, 1 Apr 2021 00:58:09 -0700
Subject: [PATCH] test(python): use constraints files to check dependency lower
 bounds
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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 https://github.com/googleapis/python-bigquery/pull/263 for an example

Source-Author: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>
Source-Date: Tue Mar 23 10:52:02 2021 -0600
Source-Repo: googleapis/synthtool
Source-Sha: 86ed43d4f56e6404d068e62e497029018879c771
Source-Link: https://github.com/googleapis/synthtool/commit/86ed43d4f56e6404d068e62e497029018879c771
---
 noxfile.py     | 22 ++++++++++++++++------
 synth.metadata |  6 +++---
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/noxfile.py b/noxfile.py
index de9e95dca..8ed1bf704 100644
--- a/noxfile.py
+++ b/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")
 
@@ -141,8 +149,10 @@ def system(session):
 
     # Install all test dependencies, then install this package into the
     # virtualenv's dist-packages.
-    session.install("mock", "pytest", "google-cloud-testutils", "psutil")
-    session.install("-e", ".")
+    session.install(
+        "mock", "pytest", "google-cloud-testutils", "psutil", "-c", constraints_path
+    )
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the system tests.
     if system_test_exists:
diff --git a/synth.metadata b/synth.metadata
index dec692fd0..62b42003a 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -19,21 +19,21 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "f5c5904fb0c6aa3b3730eadf4e5a4485afc65726"
+        "sha": "86ed43d4f56e6404d068e62e497029018879c771"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "f5c5904fb0c6aa3b3730eadf4e5a4485afc65726"
+        "sha": "86ed43d4f56e6404d068e62e497029018879c771"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "f5c5904fb0c6aa3b3730eadf4e5a4485afc65726"
+        "sha": "86ed43d4f56e6404d068e62e497029018879c771"
       }
     }
   ],