TST: refactor pip tests to use constraints files (#331)

* TST: refactor pip tests to use constraints files

Realized that tests were failing on Python 3.5 with the specified
versions and bumped the minimum pandas version to 0.20.1 (for
[pandas.testing](https://stackoverflow.com/a/53631895/101923)
support).

Added tests to run against Python 3.8 (just in time for Python 3.9 to
come out next week!)

* update changelog

* update circleci config

Author: tswast

.circleci/config.yml

@@ -15,15 +15,23 @@ jobs:
     steps:
       - checkout
       - run: ci/config_auth.sh
-      - run: nox -s unit-3.6 system-3.6
+      - run: nox -s unit-3.6
 
   "pip-3.7":
     docker:
       - image: thekevjames/nox
     steps:
       - checkout
       - run: ci/config_auth.sh
-      - run: nox -s unit-3.7 system-3.7 cover
+      - run: nox -s unit-3.7
+
+  "pip-3.8":
+    docker:
+      - image: thekevjames/nox
+    steps:
+      - checkout
+      - run: ci/config_auth.sh
+      - run: nox -s unit-3.8 system-3.8 cover
 
   "lint":
     docker:
@@ -47,11 +55,11 @@ jobs:
       - checkout
       - run: ci/config_auth.sh
       - run: ci/run_conda.sh
-  "conda-3.7-NIGHTLY":
+  "conda-3.8-NIGHTLY":
     docker:
       - image: continuumio/miniconda3
     environment:
-      PYTHON: "3.7"
+      PYTHON: "3.8"
       PANDAS: "NIGHTLY"
     steps:
       - checkout
@@ -65,6 +73,7 @@ workflows:
       - "pip-3.5"
       - "pip-3.6"
       - "pip-3.7"
+      - "pip-3.8"
       - lint
       - "conda-3.6-0.20.1"
-      - "conda-3.7-NIGHTLY"
+      - "conda-3.8-NIGHTLY"

ci/requirements-3.5.pip renamed to ci/constraints-3.5.pip

@@ -1,5 +1,5 @@
 numpy==1.13.3
-pandas==0.19.0
+pandas==0.20.1
 google-auth==1.4.1
 google-auth-oauthlib==0.0.1
 google-cloud-bigquery==1.11.1

ci/requirements-3.6.pip renamed to ci/constraints-3.6.pip

@@ -0,0 +1 @@
+pandas

ci/requirements-3.7.pip renamed to ci/constraints-3.7.pip

@@ -1,6 +1,23 @@
 Changelog
 =========
 
+.. _changelog-0.14.0:
+
+0.14.0 / TBD
+------------
+
+Dependency updates
+~~~~~~~~~~~~~~~~~~
+
+- Update the minimum version of ``pandas`` to 0.20.1.
+  (:issue:`331`)
+
+Internal changes
+~~~~~~~~~~~~~~~~
+
+- Update tests to run against for Python 3.8. (:issue:`331`)
+
+
 .. _changelog-0.13.3:
 
 0.13.3 / 2020-09-30
@@ -9,7 +26,6 @@ Changelog
 - Include needed "extras" from ``google-cloud-bigquery`` package as
   dependencies. Exclude incompatible 2.0 version. (:issue:`324`, :issue:`329`)
 
-
 .. _changelog-0.13.2:
 
 0.13.2 / 2020-05-14
@@ -26,7 +42,6 @@ Changelog
 - Fix ``AttributeError`` with BQ Storage API to download empty results.
   (:issue:`299`)
 
-
 .. _changelog-0.13.0:
 
 0.13.0 / 2019-12-12

ci/constraints-3.8.pip

@@ -10,8 +10,9 @@
 import nox
 
 
-supported_pythons = ["3.5", "3.6", "3.7"]
-latest_python = "3.7"
+supported_pythons = ["3.5", "3.6", "3.7", "3.8"]
+system_test_pythons = ["3.5", "3.8"]
+latest_python = "3.8"
 
 # Use a consistent version of black so CI is deterministic.
 black_package = "black==19.10b0"
@@ -35,7 +36,14 @@ def blacken(session):
 @nox.session(python=supported_pythons)
 def unit(session):
     session.install("pytest", "pytest-cov")
-    session.install("-e", ".")
+    session.install(
+        "-e",
+        ".",
+        # Use dependencies versions from constraints file. This enables testing
+        # across a more full range of versions of the dependencies.
+        "-c",
+        os.path.join(".", "ci", "constraints-{}.pip".format(session.python)),
+    )
     session.run(
         "pytest",
         os.path.join(".", "tests", "unit"),
@@ -77,19 +85,16 @@ def docs(session):
     )
 
 
-@nox.session(python=supported_pythons)
+@nox.session(python=system_test_pythons)
 def system(session):
     session.install("pytest", "pytest-cov")
-    session.install(
-        "-r",
-        os.path.join(".", "ci", "requirements-{}.pip".format(session.python)),
-    )
     session.install(
         "-e",
         ".",
-        # Use dependencies from requirements file instead.
-        # This enables testing with specific versions of the dependencies.
-        "--no-dependencies",
+        # Use dependencies versions from constraints file. This enables testing
+        # across a more full range of versions of the dependencies.
+        "-c",
+        os.path.join(".", "ci", "constraints-{}.pip".format(session.python)),
     )
 
     # Skip local auth tests on CI.

ci/requirements-3.7-NIGHTLY.conda renamed to ci/requirements-3.8-NIGHTLY.conda

@@ -18,7 +18,7 @@ def readme():
 
 INSTALL_REQUIRES = [
     "setuptools",
-    "pandas>=0.19.0",
+    "pandas>=0.20.1",
     "pydata-google-auth",
     "google-auth",
     "google-auth-oauthlib",
@@ -47,6 +47,7 @@ def readme():
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
         "Topic :: Scientific/Engineering",
     ],
     keywords="data",