chore: add testing requirements extra

Author: ohmayr

noxfile.py

@@ -89,8 +89,7 @@ def unit(session):
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
-    session.install("-r", "testing/requirements.txt", "-c", constraints_path)
-    session.install("-e", ".", "-c", constraints_path)
+    session.install("-e", ".[testing_extra_require]", "-c", constraints_path)
     session.run(
         "pytest",
         f"--junitxml=unit_{session.python}_sponge_log.xml",
@@ -105,8 +104,7 @@ def unit(session):
 
 @nox.session(python="3.8")
 def cover(session):
-    session.install("-r", "testing/requirements.txt")
-    session.install("-e", ".")
+    session.install("-e", ".[testing_extra_require]")
     session.run(
         "pytest",
         "--cov=google.auth",
@@ -144,8 +142,7 @@ def docs(session):
 
 @nox.session(python="pypy")
 def pypy(session):
-    session.install("-r", "testing/requirements.txt")
-    session.install("-e", ".")
+    session.install("-e", ".[testing_extra_require]")
     session.run(
         "pytest",
         f"--junitxml=unit_{session.python}_sponge_log.xml",

setup.py

@@ -27,13 +27,38 @@
     "rsa>=3.1.4,<5",
 )
 
+# Unit test requirements.
+testing_extra_require = [
+    "flask",
+    "freezegun",
+    "mock",
+    "oauth2client",
+    "pyopenssl",
+    "pytest",
+    "pytest-cov",
+    "pytest-localserver",
+    "pyu2f",
+    "pyjwt",
+    "requests",
+    "urllib3",
+    "cryptography < 39.0.0",
+    "responses",
+    "grpcio",
+    # Async Dependencies
+    "pytest-asyncio; python_version > '3.0'",
+    "aioresponses; python_version > '3.0'",
+    "asynctest; python_version > '3.0'",
+    "aiohttp < 3.10.0; python_version > '3.0'",
+]
+
 extras = {
     "aiohttp": ["aiohttp >= 3.6.2, < 4.0.0.dev0", "requests >= 2.20.0, < 3.0.0.dev0"],
     "pyopenssl": ["pyopenssl>=20.0.0", "cryptography>=38.0.3"],
     "requests": "requests >= 2.20.0, < 3.0.0.dev0",
     "reauth": "pyu2f>=0.1.5",
     "enterprise_cert": ["cryptography", "pyopenssl"],
     "pyjwt": ["pyjwt>=2.0", "cryptography>=38.0.3"],
+    "testing_extra_require": testing_extra_require,
 }
 
 with io.open("README.rst", "r") as fh: