deps: update minimum pandas to 0.21.1 (#165)

* 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` |

---

### Release Notes

<details>
<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 <bot@renovateapp.com>
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 <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: googleapis/synthtool@86ed43d

* bump minimum pandas

* update minimum pandas

* use recommended way to localize timestamps in tests

Co-authored-by: Tim Swast <swast@google.com>

.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("mock", "pytest", "pytest-cov", "-c", constraints_path)
 
-    session.install("-e", ".[fastavro,pandas,pyarrow]")
+    session.install("-e", ".[fastavro,pandas,pyarrow]", "-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 +149,15 @@ def system(session):
 
     # Install all test dependencies, then install this package into the
     # virtualenv's dist-packages.
-    session.install("mock", "pytest", "google-cloud-testutils", "google-cloud-bigquery")
-    session.install("-e", ".[fastavro,pandas,pyarrow]")
+    session.install(
+        "mock",
+        "pytest",
+        "google-cloud-testutils",
+        "google-cloud-bigquery",
+        "-c",
+        constraints_path,
+    )
+    session.install("-e", ".[fastavro,pandas,pyarrow]", "-c", constraints_path)
 
     # Run py.test against the system tests.
     if system_test_exists:

setup.py

@@ -29,7 +29,7 @@
     "libcst >= 0.2.5",
 ]
 extras = {
-    "pandas": "pandas>=0.17.1",
+    "pandas": "pandas>=0.21.1",
     "fastavro": "fastavro>=0.21.2",
     "pyarrow": "pyarrow>=0.15.0",
 }

synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/python-bigquery-storage.git",
-        "sha": "2d981460e62960f273ceb2537a70aeda8cbde5ad"
+        "sha": "8c1071337ea6c76a61f601b46254e6f07d8f5add"
       }
     },
     {
@@ -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"
       }
     }
   ],

testing/constraints-3.6.txt

@@ -9,5 +9,5 @@ google-api-core==1.22.2
 proto-plus==1.4.0
 libcst==0.2.5
 fastavro==0.21.2
-pandas==0.17.1
-pyarrow==0.15.0
+pandas==0.21.1
+pyarrow==0.15.0

tests/unit/test_reader_v1.py

@@ -427,7 +427,9 @@ def test_to_dataframe_empty_w_scalars_avro(class_under_test):
     expected["int_col"] = expected["int_col"].astype("int64")
     expected["float_col"] = expected["float_col"].astype("float64")
     expected["bool_col"] = expected["bool_col"].astype("bool")
-    expected["ts_col"] = expected["ts_col"].astype("datetime64[ns, UTC]")
+    expected["ts_col"] = (
+        expected["ts_col"].astype("datetime64[ns]").dt.tz_localize("UTC")
+    )
 
     pandas.testing.assert_frame_equal(
         got.reset_index(drop=True),  # reset_index to ignore row labels

tests/unit/test_reader_v1_arrow.py

@@ -249,7 +249,9 @@ def test_to_dataframe_empty_w_scalars_arrow(class_under_test):
     expected["int_col"] = expected["int_col"].astype("int64")
     expected["float_col"] = expected["float_col"].astype("float64")
     expected["bool_col"] = expected["bool_col"].astype("bool")
-    expected["ts_col"] = expected["ts_col"].astype("datetime64[ns, UTC]")
+    expected["ts_col"] = (
+        expected["ts_col"].astype("datetime64[ns]").dt.tz_localize("UTC")
+    )
 
     pandas.testing.assert_frame_equal(
         got.reset_index(drop=True),  # reset_index to ignore row labels