labm8/py/test: Move global conftest into //labm8/py/internal.

This moves the conftest.py file at the root of the WORKSPACE into a
module in //labm8/py/internal that is explicitly loaded as a plugin by
//labm8/py:test.

This is part of the ongoing process to eliminate conftest.py files
from the repo and to enable --noconftest arg in pytest.

github.com//issues/70

Signed-off-by: format 2020.01.16 <github.com/ChrisCummins/format>

BUILD

@@ -75,18 +75,6 @@ python_grpc_library(
     deps = ["//:config_pb"],
 )
 
-py_library(
-    name = "conftest",
-    testonly = 1,
-    srcs = ["conftest.py"],
-    visibility = ["//visibility:public"],
-    deps = [
-        "//:build_info",
-        "//labm8/py:app",
-        "//third_party/py/pytest",
-    ],
-)
-
 # Golang.
 # Gazelle directive:
 # gazelle:prefix github.com/ChrisCummins/phd

labm8/py/BUILD

@@ -709,7 +709,7 @@ py_library(
     visibility = ["//visibility:public"],
     deps = [
         ":app",
-        "//:conftest",
+        "//labm8/py/internal:pytest_plugin",
         "//third_party/py/pytest",
     ],
 )

labm8/py/internal/BUILD

@@ -55,3 +55,15 @@ python_proto_library(
     visibility = ["//labm8/py:__subpackages__"],
     deps = [":logging_pb"],
 )
+
+py_library(
+    name = "pytest_plugin",
+    testonly = 1,
+    srcs = ["pytest_plugin.py"],
+    visibility = ["//labm8/py:__subpackages__"],
+    deps = [
+        "//:build_info",
+        "//labm8/py:app",
+        "//third_party/py/pytest",
+    ],
+)

conftest.py → labm8/py/internal/pytest_plugin.py

@@ -1,4 +1,4 @@
-"""Repo-wide pytest configuration and test fixtures."""
+"""This module defines a pytest plugin for labm8."""
 import pathlib
 import socket
 import sys

labm8/py/test.py

@@ -220,6 +220,10 @@ def RunPytestOnFileOrDie(file_path: str, capture_output: bool = None):
     file_path,
     # Run pytest verbosely.
     "-v",
+    # Enable the labm8 test plugin.
+    "-p",
+    "labm8.py.internal.pytest_plugin",
+    # Let bazel handle caching.
     "-p",
     "no:cacheprovider",
   ]