chore(python): add nox session to sort python imports (#1402)

Author: parthea

synthtool/gcp/templates/python_library/noxfile.py.j2

@@ -25,7 +25,8 @@ import warnings
 import nox
 
 BLACK_VERSION = "black==22.3.0"
-BLACK_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
+ISORT_VERSION = "isort==5.10.1"
+LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
 DEFAULT_PYTHON_VERSION="{{ default_python_version }}"
 
@@ -105,7 +106,7 @@ def lint(session):
     session.run(
         "black",
         "--check",
-        *BLACK_PATHS,
+        *LINT_PATHS,
     )
     session.run("flake8", "google", "tests")
 
@@ -116,7 +117,27 @@ def blacken(session):
     session.install(BLACK_VERSION)
     session.run(
         "black",
-        *BLACK_PATHS,
+        *LINT_PATHS,
+    )
+
+
+@nox.session(python=DEFAULT_PYTHON_VERSION)
+def format(session):
+    """
+    Run isort to sort imports. Then run black
+    to format code to uniform standard.
+    """
+    session.install(BLACK_VERSION, ISORT_VERSION)
+    # Use the --fss option to sort imports using strict alphabetical order.
+    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    session.run(
+        "isort",
+        "--fss",
+        *LINT_PATHS,
+    )
+    session.run(
+        "black",
+        *LINT_PATHS,
     )
 
 

synthtool/gcp/templates/python_samples/noxfile.py.j2

@@ -30,6 +30,7 @@ import nox
 # WARNING - WARNING - WARNING - WARNING - WARNING
 
 BLACK_VERSION = "black==22.3.0"
+ISORT_VERSION = "isort==5.10.1"
 
 # Copy `noxfile_config.py` to your directory and modify it instead.
 
@@ -168,12 +169,32 @@ def lint(session: nox.sessions.Session) -> None:
 
 @nox.session
 def blacken(session: nox.sessions.Session) -> None:
+    """Run black. Format code to uniform standard."""
     session.install(BLACK_VERSION)
     python_files = [path for path in os.listdir(".") if path.endswith(".py")]
 
     session.run("black", *python_files)
 
 
+#
+# format = isort + black
+#
+
+@nox.session
+def format(session: nox.sessions.Session) -> None:
+    """
+    Run isort to sort imports. Then run black
+    to format code to uniform standard.
+    """
+    session.install(BLACK_VERSION, ISORT_VERSION)
+    python_files = [path for path in os.listdir(".") if path.endswith(".py")]
+
+    # Use the --fss option to sort imports using strict alphabetical order.
+    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    session.run("isort", "--fss", *python_files)
+    session.run("black", *python_files)
+
+
 #
 # Sample Tests
 #

synthtool/languages/python.py

@@ -268,9 +268,9 @@ def owlbot_main() -> None:
 
         py_samples(skip_readmes=True)
 
-        # run blacken session for all directories which a noxfile
+        # run format nox session for all directories which have a noxfile
         for noxfile in Path(".").glob("**/noxfile.py"):
-            s.shell.run(["nox", "-s", "blacken"], cwd=noxfile.parent, hide_output=False)
+            s.shell.run(["nox", "-s", "format"], cwd=noxfile.parent, hide_output=False)
 
     configure_previous_major_version_branches()